Scholarly Articles on E. Cuniculi

This is a curated set of references from recent scholarship on E. Cuniculi in rabbits. For articles on other rabbit health topics, visit this page. For articles on behavior, welfare, and the rabbit human relationship, visit this page.

Editor’s Note: We understand that many of these articles are done in the context of biomedical research laboratories and that the conditions are not sufficient to satisfy the well-being requirements of a group like House Rabbit Society. Although we do  not endorse such studies, we elected to include these studies to ensure that the most recent data on these issues are available to our readers.


Smith, T., & Florence, L. (1925). Encephalitozoon cuniculi as a kidney parasite in the rabbit. Journal of Experimental Medicine, 41(1), 25-35.
Abstract: A spontaneous epidemic of nephritis among young rabbits associated with a protozoan parasite has been observed in a certain breeding stock since 1918. It is regarded as a nest infection. The parasite is tentatively classed among the microsporidia and the stages encountered are regarded as vegetative which may perhaps pass through several generations in the same host. It is a parasite of the epithelial cell, provoking no immediate host reactions. These are supposed to follow injury such as destruction of the epithelium and denudation and plugging of the tubules. The localizations in the brain are also without cell reaction, except under special conditions, and the many cell foci present are attributed to coccidia and perhaps bacteria and other intestinal parasites. The kidneys are looked upon as the normal habitat and the brain parasites as aberrant and outside the normal cycle unless it can be shown that the spores discharged into the circulation may again multiply in some organ like the kidneys in direct communication with the exterior. It is highly probable that many reported cases of nephritis among older rabbits used in experiments had their origin in an early invasion of the parasite described.

Robinson, J. J. (1954). Common infectious disease of laboratory rabbits questionably attributed to Encephalitozoon cuniculi. AMA archives of pathology, 58(1), 71-84.
[No Abstract Available]

Chalupský J, Vávra J, Bedrník P. (1973). Detection of antibodies to Encephalitozoon cuniculi in rabbits by the indirect immunofluorescent antibody test. Folia Parasitol (Praha). 20(4):281-4.
[No Abstract Available]

Jackson, S. J., Solorzano, R. F., & Middleton, C. C. (1973). An indirect fluorescent antibody test for antibodies to Nosema cuniculi (Encephalitozoon) in rabbits. In Proceedings, annual meeting of the United States Animal Health Association (No. 77, p. 478).
[No Abstract Available]

Kitaoka, M. (1975). Interference between Rickettsia orientalis and Encephalitozoon cuniculi in the same cell. Zhonghua Minguo wei sheng wu xue za zhi= Chinese journal of microbiology, 8(2), 179. [No Abstract Available]

PAKES, S. P., SHADDUCK, J. A., & CALI, A. (1975). Fine structure of Encephalitozoon cuniculi from rabbits, mice and hamsters. The Journal of protozoology, 22(4), 481-488.
Abstract: Fine structure and development of Encephalitozoon cuniculi from rabbits were studied in rabbit choroid plexus (CP) cell cultures and were compared to hamster and mouse microsporida. Sporoplasms had a single limiting membrane and contained a large nucleus. Proliferative forms (schizonts) had double outer membranes, the outermost being associated with the formation of the limiting membrane of vacuoles formed within the host cell cytoplasm. These organisms were often binucleate and divided to form sporonts. Sporonts divided once to form 2 sporoblasts which developed into electron-dense spores. Spores had a thick, 3-layered wall and contained a polar filament. The developmental cycle of E. cuniculi in rabbit CP cultures progressed rapidly. Sporoplasms were observed in host cells at 3 hr postinoculation (PI). By 24 hr PI proliferative forms were associated with host cell cytoplasmic vacuoles which contained developing organisms. Mature spores were present in vacuoles by 2 days PI, indicating that the life cycle in the CP system is approximately 48 hr. The fine structure and the sequential developmental cycle of the mouse and hamster isolates were observed to be identical to those of the rabbit isolate and different from those of the genus Nosema. It is proposed, therefore, that the 3 organisms represent the same species, Encephalitozoon cuniculi.

Ashton, N. O. R. M. A. N., Cook, C., & Clegg, F. (1976). Encephalitozoonosis (nosematosis) causing bilateral cataract in a rabbit. British Journal of Ophthalmology, 60(9), 618-631.
Abstract: Bilateral cataract due to a microsporidan believed to be Encephalitozoon cuniculi (also called Nosema cuniculi) is described as an incidental finding in a laboratory rabbit. The route of infection and the significance of the findings are discussed. This is apparently the first report of cataract due to this cause.

Cox, J. C. (1977). Altered immune responsiveness associated with Encephalitozoon cuniculi infection in rabbits. Infection and immunity, 15(2), 392-395.
Abstract: The variation in immune response of two unrelated colonies of laboratory rabbits to high doses of heat-killed Brucella abortus strain 19 was investigated. One was a mixed-breed, multicolored colony in which a high prevalence of encephalitozoonosis had been recorded, whereas the other rabbits were derived from a colony of Dutch-marked specific-pathogen-free rabits. Although considerable variation in the immune response between individual rabbits was noticed at all bleeds, rabbits infected with Encephalitozoon cuniculi showed, on comparison with uninfected rabbits from either colony, a depressed immunoglobulin G response from week 5 of the antigen injection schedule and, from week 8, an elevated immunoglobulin M response.

Waller, T. (1977). The india-ink immunoreaction: a method for the rapid diagnosis of encephalitozoonosis. Laboratory Animals, 11(2), 93-97.
Abstract: Sera from 37 rabbits were assayed for antibodies against Encephalitozoon cuniculi (Nosema cuniculi) by the india-ink immunoreaction and the indirect fluorescent antibody tests: all animals seropositive to the former were also positive to the latter test. 27 of the rabbits were also tested for skin hypersensitivity and then autopsied. Animals positive to the skin test were also positive to the serological tests. At autopsy 18 of 22 rabbits positive in the immunological tests showed lesions typical of encephalitozoonosis. Sera from 200 rabbits originating from 6 institutes were assayed by the india-ink test: seropositive rabbits were found from all institutes (9.1 to 81.9% incidence), with serum titres ranging from 1:125 to 1:5000. The india-ink test appears to be a rapid and convenient method for diagnosis of encephalitozoonosis in rabbits.

Cox, J. C., Gallichio, H. A., Pye, D., & Walden, N. B. (1977). Application of immunofluorescence to the establishment of an Encephalitozoon cuniculi-free rabbit colony. Laboratory animal science, 27(2), 204-209.
Abstract: Serologic screening of a rabbit breeding colony over a 9-month period showed that all 9-week-old rabbits with Encephalitozoon cuniculi infection were born of E cuniculi-infected does. This observation, obtained from studies on 395 young rabbits, suggested that transmission of infection is either transplacental or the result of close contact soon after birth. On this basis, 16 young healthy rabbits, seronegative to E cuniculi, were isolated and tested at 2-week intervals for antibodies to E cuniculi. In the first 2 months, seven rabbits showed indications of developing antibodies to E cuniculi and were immediately removed from the colony. The remaining rabbits along with their 52 offspring were tested for serum antibodies for a further 16 months and no rabbit became seropositive. Eight months after establishment of the colony, three does, one buck and six 12-week-old rabbits were killed. Macroscopic and extensive histologic and immunofluorescence examinations failed to reveal any evidence of infection with E cuniculi. These results showed that serological screening for E cuniculi infection by immunofluorescence is a simple yet adequate procedure for establishing a rabbit colony free of encephalitozoonosis.

Wosu, N. J., Shadduck, J. A., Pakes, S. P., Frenkel, J. K., Todd, J. K., & Conroy, J. D. (1977). Diagnosis of encephalitozoonosis in experimentally infected rabbits by intradermal and immunofluorescence tests. Laboratory animal science, 27(2), 210-216.
Abstract: The indirect immunofluorescence antibody test was performed on serial blood samples from eight young New Zealand White rabbits with experimental encephalitozoonosis. The test showed seroconversion in six of the eight infected rabbits by the 8th day after inoculation and in all rabbits by the 15th day. Antibody titers reached a peak by about the 36th day after inoculation and remained significantly elevated until the termination of the experiment at 84 days after inoculation. None of four sham-inoculated rabbits showed an immunofluorescence response by the 60th day after inoculation. Immunofluorescence and intradermal test responses were compared before infection and at the 60th day after inoculation in a total of 32 experimentally infected rabbits. Both tests were equally effective (100%) in detecting infected animals. Six of eight (first group) and 22 of 24 (second group) experimentally infected rabbits were confirmed histologically to have lesions compatible with encephalitozoonosis. No cross reactions were observed between Encephalitozoon cuniculi and Toxoplasma gondii, Eimeria perforans, or Eimeria stiedai by intradermal test or immunofluorescence test.

Wosu, N. J., Olsen, R., Shadduck, J. A., Koestner, A., & Pakes, S. P. (1977). Diagnosis of experimental encephalitozoonosis in rabbits by complement fixation. Journal of Infectious Diseases, 135(6), 944-948.
Abstract: A complement-fixation (CF) test has been developed for detection of experimental encephalitozoonosis in rabbits. The antigen consisted of disrupted homogenates of Encephalitozoon cuniculi spores grown in and released from rabbit choroid plexus tissue culture cells. The test was sensitive and capable of detecting experimental encephalitozoonosis in rabbits as early as 15 days after intracerebral infection. The test was specific for infected animals, and no cross-reactivity was demonstrated between E. cuniculi antigen and Nosema apis, Trypanosoma congolese, Trypanosoma cruzi, rabbit liver powder, rabbit brain powder, and rabbit choroid plexus cell culture. Sera from rabbits infected with Toxoplasma gondii, Eimeria stiedai, and Eimeria perforans did not exhibit antibodies to E. cuniculi. No CF-inhibition activity was detected.

Pye, D., & Cox, J. C. (1977). Isolation of Encephalitozoon cuniculi from urine samples. Laboratory animals, 11(4), 233-234.
Abstract: Encephalitozoon cuniculi was isolated from the urine of infected rabbits using human and canine tissue cultures. The organism was isolated from 7 of 11 contaminated urines from seropositive animals. The advantages of urine over tissue as a source of E. cuniculi are that it is obtainable from living animals, can be examined for the presence of organisms, and is essentially free of cells likely to overgrow the tissue cultures used for isolation.

Cox, J. C., & Gallichio, H. A. (1978). Serological and histological studies on adult rabbits with recent, naturally acquired encephalitozoonosis. Research in veterinary science, 24(2), 260-261.
Abstract: Twenty adult rabbits were killed two to 12 weeks after antibodies to Encephalitozoon cuniculi were first detected in their sera. Specimens of urine were examined for E cuniculi and sections of kidneys and brains were examined both for organisms and lesions consistent with encephalitozoonosis. Organisms were observed in the kidneys from two weeks after the appearance of antibodies, and histological lesions in the kidneys were observed after five weeks. However, organisms were rarely seen in the brain and lesions in this organ were infrequent and, generally, not present until at least eight weeks after the first detectable antibody. The results indicate the course of natural infection of encephalitozoonosis in rabbits and show that serology is the most sensitive procedure for its early diagnosis.

Gannon, J. (1978). The immunoperoxidase test diagnosis of Encephalitozoon cuniculi in rabbits. Laboratory animals, 12(3), 125-127.
Abstract: Sera collected from both naturally and artificially infected rabbits were found to show excellent correlation when examined for the presence of Encephalitozoon cuniculi antibodies using the immunoperoxidase and immunofluorescence tests. Out of 85 randomly selected rabbits, 21 were found to be serologically positive using both the tests. However, lesions which could be attributed to E. cuniculi infection were only demonstrated in 16.

Waller, T., Morein, B., & Fabiansson, E. (1978). Humoral immune response to infection with Encephalitozoon cuniculi in rabbits. Laboratory animals, 12(3), 145-148.
Abstract: Parenteral administration of Encephalitozoon cuniculi induced an antibody response within 7–11 days. Peroral administration was less effective since only 2 of 6 animals showed seroconversion; they became seropositive within 14–21 days. Sera from animals which became seropositive had high antibody titres during the whole test period. Immune sera from 3 animals were fractionated by gel filtration. With the india-ink immunoreaction test, antibodies to E. cuniculi were found only in the 7S fractions, while the indirect fluorescent-antibody test detected them in fractions 19S and 7S. The 7S fractions were identified as IgG and the 19S fractions as IgM. A program for eradication of encephalitozoonosis, based on these results, is discussed.

Bywater, J. E., & Kellett, B. S. (1978). Encephalitozoon cuniculi antibodies in a specific-pathogen-free rabbit unit. Infection and immunity, 21(2), 360-364.
Abstract: We describe our discovery of Encephalitozoon cuniculi antibodies in a specific-pathogen-free rabbit colony. Small-sized samples had failed to reveal the presence of infection with a prevalence of about 5%. Using an India ink immunoreaction test by which we were able to visualize both negative and positive reactions, we were able to undertake a 100% screen of the colony of more than 700 rabbits and to repeat this 4 weeks later when we had culled the positive reactors. By collating the results of those tests with the results of tests on previously collected samples, we have been able to discuss and observe age and sex susceptibilities and the mode of transmission of the naturally occurring disease.

Wilson, J. M. (1979). Encephalitozoon cuniculi in wild European rabbits and a fox. Research in veterinary science, 26(1), 114-114.
[No Abstract Available]

Shadduck, J. A., & Geroulo, M. J. (1979). A simple method for the detection of antibodies to Encephalitozoon cuniculi in rabbits. Laboratory animal science, 29(3), 330-334.
Abstract: Rabbit antibodies against Encephalitozoon cuniculi were detected in an indirect microagglutination test using a bead substrate to which anti-rabbit immunoglobin G light and heavy chain antibodies were coupled. The test was positive using immune whole serum or F(ab)’ and F(ab)’2 fragments of immunoglobin G but negative using the F(c) fragment. The reaction was blocked by saturating the beads with rabbit serum or by absorbing positive sera with excess Encephalitozoon cuniculi. The test provided a simple method to detect antibodies to Encephalitozoon cuniculi, did not require elaborate equipment and could be performed using frozen antigen.

COX, J. C., HAMILTON, R. C., & ATTWOOD, H. D. (1979). An investigation of the route and progression of Encephalitozoon cuniculi infection in adult rabbits. The Journal of Protozoology, 26(2), 260-265.
Abstract: Rabbits infected either orally or intratracheally with cell culture-grown Encephalitozoon cuniculi were monitored regularly for serum antibody levels and E. cuniculi in the urine. Their responses were compared with intravenously inoculated and uninoculated control rabbits. All rabbits receiving E. cuniculi developed serum antibodies, generally within 3 weeks, and excreted E. cuniculi by 6 weeks. In the acute stage of infection, the organs most affected were lung, kidney and liver; the brain and gut were unaffected. However, during chronic infection, the brain, kidney, and heart were the only organs found to be involved. Antibody levels were very high at this stage. Thus both the oral and tracheal routes may be normal routes of infection with E. cuniculi in adult rabbits.

Pye, D., & Cox, J. C. (1979). Simple focus assay for Encephalitozoon cuniculi. Laboratory animals, 13(3), 193-196.
Abstract: In this is vitro infectivity assay for Encephalitozoon cuniculi, lesions due to the organism appeared as macroscopically distinct foci. The number of such foci was used as a direct measure of the number of infectious units in the original sample. The expected correlation between focus-forming units and 50% infectious doses was observed in limit dilution experiments.

Bywater, J. E. C., & Kellett, B. S. (1979). Humoral immune response to natural infection with Encephalitozoon cuniculi in rabbits. Laboratory animals, 13(4), 293-297.
Abstract: Sera from 4 generations of a family of rabbits having a natural Encephalitozoon cuniculi infection were investigated. Antibodies were demonstrated in a litter of newborn rabbits and in another litter 11 days old. Histoloigcal examination of the brains and kidneys of these animals failed to reveal lesions attributable to the disease. Sera from a further litter of 2 rabbits, taken at weekly intervals from 4 to 42 weeks of age, revealed a low initial antibody titre which regressed to an undetectable level. After an interval, titres rose and then plateaued to the end of the period of observation. Encephalitozoon cuniculi infections in the dams of all the litters were confirmed by antibody assay and by histology. Parallel titration of samples treated and not treated with 2-mercaptoethanol showed that the india-ink immunoreaction demonstrates only immunoglobulin G.

Owen, D. G., & Gannon, J. (1980). Investigation into the transplacental transmission of Encephalitozoon cuniculi in rabbits. Laboratory animals, 14(1), 35-38.
Abstract: An investigation into the transmission of Encephalitozoon cuniculi was undertaken in both naturally- and experimentally-infected rabbits. Only 2 nurslings were found with rising antibody titres at 8-10 weeks of age, when infection could have been caused by environmental contamination.

Niederkorn, J. Y., & Shadduck, J. A. (1980). Role of antibody and complement in the control of Encephalitozoon cuniculi infections by rabbit macrophages. Infection and immunity, 27(3), 995-1002.
Abstract: The capacity of mononuclear peritoneal macrophages to phagocytose Encephalitozoon cuniculi was tested in vitro. Normal rabbit serum or cell culture medium had little effect on the rate of removal of organisms by rabbit peritoneal macrophages. Treatment with immune rabbit serum or immune rabbit immunoglobulin G significantly (P less than 0.001) increased phagocytosis of E. cuniculi. Guinea pig complement was found to significantly (P less than 0.001) enhance the phagocytosis of antibody-treated E. cuniculi. With few exceptions, induced (peritoneal exudate) macrophages were no more effective than unstimulated (resident) macrophages in the phagocytosis of E. cuniculi. Secondary lysosomes labeled with ferritin were seen fusing with phagosomes containing immune rabbit serum-treated parasites. Phagosome-lysosome fusion was not observed when parasites were treated with either normal rabbit serum or culture medium. The results of the present study suggest a role for antibody enhancement of phagocytosis and intracellular killing as a mechanism of resistance to encephalitozoonosis in rabbits.

Cox, J. C., Pye, D., Edmonds, J. W., & Shepherd, R. (1980). An investigation of Encephalitozoon cuniculi in the wild rabbit Oryctolagus cuniculus in Victoria, Australia. Epidemiology & Infection, 84(2), 295-300.
Abstract: Sera from 823 wild rabbits (Oryctolagus cuniculus) collected from a number of geographic regions of Victoria, Australia over the past eight years were examined for antibodies to Encephalitozoon cuniculi, along with sera from 46 hares (Lepus europaeus) (Pallas) and 57 New Zealand wild rabbits. No sera were positive, implying that this common laboratory rabbit parasite is absent from wild rabbits in these areas. However, wild rabbits were found to be readily infected by the oral route with small numbers of tissue-culture-grown spores of E. cuniculi. A possible explanation for the absence of encephalitozoonosis in wild rabbits is that E. cuniculi infection places them at a biological disadvantage for survival. The natural hygiene habit of wild rabbits may also significantly decrease post-natal infection.

Bywater, J. E. C., Kellett, B. S., & Waller, T. (1980). Encephalitozoon cuniculi antibodies in commercially-available rabbit antisera and serum reagents. Laboratory animals, 14(2), 87-89.
[No Abstract Available]

Gannon, J. (1980). A survey of Encephalitozoon cuniculi in laboratory animal colonies in the United Kingdom. Laboratory animals, 14(2), 91-94.
Abstract: Of 38 animal colonies serologically examined for Encephalitozoon cuniculi, 1 mouse, 2 rat and 4 guineapig colonies were positive. A further survey showed that the prevalence within mouse, rat, guineapig and rabbit colonies varied between 25 and 95%. Guineapigs housed with infected rabbits are at a greater risk of being infected than those housed separately. Nephritis was a common feature, but cerebral granulomata were not seen.

Shadduck, J. A. (1980). Effect of fumagillin on in vitro multiplication of Encephalitozoon cuniculi. The Journal of protozoology, 27(2), 202-208.
Abstract: Encephalitozoon cuniculi (Levaditi, Nicolau & Schoen) is an obligate intracellular pathogenic parasite of rabbits, carnivores, laboratory rodents, and a variety of other mammals. Cell cultures of rabbit and canine cells were infected with rabbit and dog isolates of E. cuniculi. Four days later 5 microgram/ml of fumagillin was introduced into the culture medium. The multiplication of the parasite was inhibited within 48 h and this effect was maintained as long as the antibiotic remained in the medium. There was no effect when spores and proliferative forms of the parasite were incubated with fumagillin before being used for infecting host cells. No infection occurred, however, if the antibiotic was added to the culture medium before introduction of E. cuniculi. On electron-microscopic examination, the treated parasites were found to have severe cytoplasmic swelling, vesicular distortion of the plasma membrane, and marked reduction in cytoplasmic ribosomes. it was concluded that fumagillin blocks multipliation of E. cuniculi in vitro. The drug may be useful for the treatment or prevention of spontaneous encephalitozoonosis.

Cox, J. C., & Ross, J. (1980). A serological survey of Encephalitozoon cuniculi infection in the wild rabbit in England and Scotland. Research in veterinary science, 28(3), 396-396.
Abstract: Sera from 175 wild rabbits trapped in England or Scotland over the past two years were tested for antibodies to Encephalitozoon cuniculi. No sera were positive, suggesting that this common laboratory rabbit pathogen is rare in wild rabbits in these areas.

Lyngset, A. (1980). A survey of serum antibodies to Encephalitozoon cuniculi in breeding rabbits and their young. Laboratory animal science, 30(3), 558-561.Abstract: Screening of a rabbit breeding colony by the India-ink immunoreaction test revealed that 73% of the animals had antibodies to Encephalitozoon cuniculi. The study also indicated the passive transmission of antibodies from infected dams to their offspring. Ninety-five percent of the rabbits born to seropositive dams had maternal antibodies to Encephalitozoon cuniculi up to the age of 4 weeks with titers ranging from 1:25 to 1:800. After elimination of maternally transferred antibodies, about 50% of the young rabbits seroconverted; and from the age of 8–10 weeks, serum antibody titers over 1:800 were detectable. When these animals were tested again at 14 weeks, most of them had titers of 1:1600 or higher.

Hamilton, R. C., & Cox, J. C. (1981). The ultrastructure ofEncephalitozoon cuniculi growing in renal tubules of rabbits. Zeitschrift für Parasitenkunde, 64(3), 271-278.
Abstract: A wild type rabbit infected orally with cell culture-grown Encephalitozoon cuniculi. Twelve weeks after infection the rabbit was killed and blocks of kidney tissue were fixed for histology and electron microscopy. E. cuniculi were observed within kidney collecting tubule cells. The ultrastructure and development of E. cuniculi in these cells was similar to that described in cultured cells and peritoneal macrophages.

Cox, J. C., Horsburgh, R., & Pye, D. (1981). Simple diagnostic test for antibodies to Encephalitozoon cuniculi based on enzyme immunoassay. Laboratory animals, 15(1), 41-44.
[No Abstract Available]

Pakes, S. P., Shadduck, J. A., Feldman, D. B., & Moore, J. A. (1984). Comparison of tests for the diagnosis of spontaneous encephalitozoonosis in rabbits. Laboratory animal science, 34(4), 356-359.
Abstract: The effectiveness of immunofluorescence, complement fixation, microagglutination serologic tests, intradermal skin test, and detection of histologic lesions were compared for use in diagnosis of spontaneous encephalitozoonosis in rabbits. The India ink and microbead agglutination reactions were compared with immunofluorescence and complement fixation by testing 11 single or pooled sera. Serologic tests correlated best with each other and less well with intradermal tests or presence of lesions. Immunofluorescence, India ink reaction and microbead agglutination were equally useful in detecting antibodies to Encephalitozoon cuniculi. The intradermal test correlated best with the presence of detectable lesions.

Cox, J. C., Hamilton, R. C., Pye, D., & Edmonds, J. W. (1986). The infectivity ofEncephalitozoon cuniculi in vivo and in vitro. Zeitschrift für Parasitenkunde, 72(1), 65-72.
Abstract: The infectivity of Encephalitozoon cuniculi grown in cell cultures was determined in cultured cells and in wild and domestic rabbits. The ratio of the total to tissue culture viable count was 1,300 (median of seven determinations). The mean ratio of intact spore count to total count, as determined by electron microscopy was 0.12. Although variation between infectivity experiments was large, the median animal infective dose contained 51 FFU (cell culture focus-forming units) for wild rabbits (Oryctolagus cuniculus) and 40 FFU for domestic rabbits. These two infectivities were not statistically different.

Scharmann, W., Reblin, L., & Griem, W. (1986). Infection of rabbits with encephalitozoon cuniculi. Berliner und Munchener tierarztliche Wochenschrift, 99(1), 20-24.
[No Abstract Available]

Wilson, J. M. (1986). Can Encephalitozoon cuniculi cross the placenta?. Research in veterinary science, 40(1), 138.
Abstract: Laboratory rabbits and mice were challenged with Encephalitozoon cuniculi at three different stages of gestation to determine whether the parasite crosses the placenta. No transplacental transmission could be demonstrated.

Kunstýř, I., Lev, L., & Naumann, S. (1986). Humoral antibody response of rabbits to experimental infection with Encephalitozoon cuniculi. Veterinary parasitology, 21(4), 223-232.
Abstract: Six female rabbits (Oryctolagus cuniculus) were experimentally infected intravenously with approximately 1.5 X 10(7) live spores of Encephalitozoon cuniculi. Head tilt was observed as the single clinical sign in only one of the six animals. Antibody response was registered over 68 days postinfection using the indirect immunofluorescence test (IFT) for IgM and IgG, and the carbon immunoassay (CIA). IgG titers reached a level of 160-2560 after a latent phase of 13-28 days, followed by a 2-4 week relatively steep increase. The IgM seroconversion was faster than that of IgG and occurred at the beginning of the antibody response. Thus, simultaneous detection of both IgM and IgG allowed the infection to be identified as recent. Long, short, and episodic antibody responses could be distinguished: the IgG titer continued to increase on Day 68 in one animal (long response) and began to decrease between Days 45 and 63 in three other animals (short response). In two additional animals the seroconversion was very short, occurring between Days 13 and 41, and 28 and 52, respectively (episodic response). The CIA proved to be specific, reliable, and simple to perform; titers were slightly higher than in the IFT. Parasite pseudocysts were detected scattered throughout the brain on Day 68 in four of the six rabbits. The persistence of antigen in the brain did not correlate with antibody response, which in most cases was shorter.

Kimman, T. G., & Akkermans, J. P. (1987). Encephalitozoon cuniculi in a rabbit-breeding colony. Tijdschrift voor diergeneeskunde, 112(24), 1405-1409.
Abstract: A case of Encephalitozoon cuniculi infection in a rabbitry is reported. After the introduction of new rabbits in 1984, problems arose accompanied by serious losses among rabbits of all ages. Affected animals showed muscular weakness, emaciation, polydipsia and polyuria and died within various periods. Some of the affected animals also showed neurological symptoms. When two animals were examined at autopsy lesions typical of encephalitozoonis were observed: small granulomas in the brain and chronic interstitial nephritis associated with tubular degeneration. Encephalitozoon cuniculi was identified in the affected renal tubules and, in small numbers, also in the brain and the liver. The pathogenesis, epidemiology and possibilities of control are briefly discussed.

Beckwith, C., Peterson, N., Liu, J. J., & Shadduck, J. A. (1988). Dot enzyme-linked immunosorbent assay (dot ELISA) for antibodies to Encephalitozoon cuniculi. Laboratory animal science, 38(5), 573-576. Abstract: A dot-ELISA procedure was developed to detect antibodies against Encephalitozoon cuniculi. Sera from 84 rabbits, 22 dogs, 18 squirrel monkeys and 200 mice were tested by dot-ELISA and most also were tested by immunofluorescence. Comparison of the two tests showed that there was excellent agreement of the results (Kappa values greater than or equal to 0.74) in all four species. Dot-ELISA is a simple, quantitative, rapid alternative to immunofluorescence when large numbers of serum samples must be evaluated.

Ansbacher, L., Nichols, M. F., & Hahn, A. W. (1988). The influence of Encephalitozoon cuniculi on neural tissue responses to implanted biomaterials in the rabbit. Laboratory animal science, 38(6), 689-695.
Abstract: Laboratory rabbits are commonly used for testing the tissue response of neural device biomaterials. Rabbits of many colonies in the U.S. are infected by the intracellular microsporidian parasite, Encephalitozoon cuniculi, with rates of infection ranging from 15 to 76% (1). Several authors have suggested that infection by this parasite may alter immune system response and experimental results. We report that infection by E. cuniculi made the interpretation of results more difficult and altered the animals’ responsiveness to implanted platinum wires coated with various polymers such as glow discharge methane, Parylene C, or polyimide. Edema, neuronal and glial reaction, and inflammatory responses to the coated wires were quantitated at four sites in each animal. Inconsistency of response in all measured parameters was found, both between animals and between sites in infected animals. Infected animals showed the greatest variability, primarily in the degree of inflammatory reaction. Parylene C was found to induce the most severe inflammatory reaction, an unexpected finding. No consistent reaction to any of the coating materials was found in this study. We believe that this variability in response was primarily due to infection by E. cuniculi. Our results suggest that rabbits should not be used for tissue compatibility testing of neural device biomaterials until the animals are free of E. cuniculi infestation as demonstrated by serologic screening.

Wicher, V., Baughn, R. E., Fuentealba, C., Shadduck, J. A., Abbruscato, F., & Wicher, K. (1991). Enteric infection with an obligate intracellular parasite, Encephalitozoon cuniculi, in an experimental model. Infection and immunity, 59(7), 2225-2231.
Abstract: Rabbits were intrarectally infected with 3 doses (5 x 10(3), 5 x 10(5), and 5 x 10(7] of an obligate intracellular parasite, Encephalitozoon cuniculi, with or without prior colonic lavages. Although chronic administration of enemas seems to interfere to some degree with the intestinal translocation of the parasite, systemic infection was observed in both manipulated and nonmanipulated animals. The animals responded with antibodies of immunoglobulin A (IgA) and IgG isotypes, reflecting the route of infection. They also produced significant amounts of circulating immune complexes composed of IgA and IgG antibodies and E. cuniculi antigens. Lesions compatible with encephalitozoonosis were seen in the liver, kidney, lung, and brain. In all instances, nonmanipulated animals had more severe lesions than manipulated rabbits given the same dose of parasites. Levels of serum antibodies, circulating immune complexes, and histopathologic changes were associated with the infection dose. The presented data suggest that human microsporidiosis may also be transmitted via the rectal route. It is, therefore, of clinical relevance in view of several reports of microsporidian infections in patients with acquired immunodeficiency.

Greenstein, G., Drozdowicz, C. K., Garcia, F. G., & Lewis, L. L. (1991). The incidence of Encephalitozoon cuniculi in a commercial barrier-maintained rabbit breeding colony. Laboratory animals, 25(4), 287-290.
Abstract: Between 1982 and 1987 sera from 4952 New Zealand White rabbits (Oryctolagus cuniculus) obtained from a single commercial supplier were tested for the presence of antibodies to Encephalitozoon cuniculi. A commercially available carbon immunoassay test kit was used. Initially 32.9% of the rabbits were seropositive with the number progressively decreasing to 2.3% by 1987. The reason for the significant decline in the incidence of infection was most likely due to a selection process for breeding stock instituted by the supplier based upon productivity, posture and weight of each animal.

Wesonga, H. O., & Munda, M. (1992). Rabbit encephalitozoonosis in Kenya. Laboratory animals, 26(3), 219-221.
Abstract: Encephalitozoon cuniculi infection was diagnosed in a laboratory rabbit breeding colony at Muguga, Kenya. This is the first report of the disease in rabbits in Kenya. Post-mortem examination showed gross renal lesions and the presence of the parasite in histological sections of the cerebrum and cerebellum. On Gram stain, spores were observed in the kidney sections.

Packham, D. K., Hewitson, T. D., Whitworth, J. A., & Kincaid-Smith, P. S. (1992). Glomerulosclerosis and hyalinosis in rabbits. Pathology, 24(3), 164-169.
Abstract: Histological appearances of remnant kidney in female New Zealand white rabbits undergoing left nephrectomy at 6 mths were studied. All 20 rabbits had evidence of previous Encephalitozoon cuniculi (E. cuniculi) infection. Half of the 10 uninephrectomized and 10 control animals completed 3 pregnancies before sacrifice (15 mths). Twelve of 30 kidneys at sacrifice showed focal and segmental hyalinosis and sclerosis (FSHS), a lesion not previously reported in rabbits. Four of 5 kidneys in both uninephrectomized pregnant and uninephrectomized virgin animals showed FSHS compared with 2 of 10 in both control pregnant and non-pregnant rabbits (p = 0.0026). More glomeruli were sclerosed in control pregnant (median 3.5%) than non pregnant animals (median 0.4%) (p < 0.005). Median right kidney weights per kilogram body weight were greater in previously nephrectomized animals (3.9 gm/kg) than controls (2.6 gm/kg), (p < 0.001). Absolute glomerular area was increased in hypertrophied kidneys, however, after correction for kidney weight, glomerular area was smaller in previously uninephrectomized animals than controls (p < 0.0001).

Fuentealba, I. C., Mahoney, N. T., Shadduck, J. A., Harvill, J., Wicher, V., & Wicher, K. (1992). Hepatic lesions in rabbits infected with Encephalitozoon cuniculi administered per rectum. Veterinary pathology, 29(6), 536-540.
Abstract: Microsporidia have been recognized recently as opportunistic pathogens in acquired immunodeficiency syndrome patients. In an attempt to develop an animal model of enteric microsporidiosis, adult (5 to 6 months old) male Flemish Giant rabbits from a closed New York colony were administered 5 x 10(3), 5 x 10(5), and 5 x 10(7) Encephalitozoon cuniculi per rectum. Rabbits given 5 x 10(5) and 5 x 10(7) E. cuniculi had moderate granulomatous periportal infiltrates, characterized by the presence of numerous macrophages, epithelioid cells and a few multinucleated giant cells, lymphocytes, and plasma cells. Inflammatory cells also were seen infiltrating the tunica adventitia and tunica media of hepatic portal veins and branches of the hepatic artery. This study demonstrates that administration of E. cuniculi per rectum to rabbits results in infection that is characterized by high frequency and severity of hepatic lesions.

Zierdt, C. H., Gill, V. J., & Zierdt, W. S. (1993). Detection of microsporidian spores in clinical samples by indirect fluorescent-antibody assay using whole-cell antisera to Encephalitozoon cuniculi and Encephalitozoon hellem. Journal of clinical microbiology, 31(11), 3071-3074.
Abstract: Three polyclonal mouse antisera, to Encephalitozoon cuniculi, Nosema algerae, and Nosema corneum, and two polyclonal rabbit antisera, to E. cuniculi and Encephalitozoon hellem, were used in an indirect fluorescent-antibody assay (IFA) with Enterocytozoon bieneusi, E. cuniculi, and Encephalitgozoon. hellem spores (spores of the last two were taken from culture). Enterocytozoon bieneusi cannot be cultured. By IFA, antisera to E. cuniculi and E. hellem reacted strongly and equally with each other’s spores. The mouse antisera reacted strongly with the homologous species, but for these there was segmental and particulate or “dot” staining of heterologous microsporidian spores, indicating cross-reactions with more selected antigens. In fecal samples, cross-reactions with both mouse and rabbit antisera were sometimes seen with different yeast species, with species of streptococci, and species of gram-negative rods. There were no cross-reactions to staphylococci. Enterocytozoon bieneusi was easily identified in duodenal and colonic biopsies, duodenal and colonic fluids, and feces of symptomatic AIDS patients by IFA. In a study of 12 AIDS patients with diarrhea, the new IFA identified microsporidia in all of 11 fecal samples, three colon fluids, six duodenal fluids, and three duodenal biopsy touch preparations. Although the fecal sample of 1 of the 12 was negative, the patient’s duodenal fluid contained microsporidian spores by IFA.

Ditrich, O. (1994). In vitro sensitivity of Encephalitozoon cuniculi and E. hellem to albendazole. J Eukaryot Microbiol, 41, 37S.
[No Abstract Available]

Beauvais, B., Sarfati, C., Challier, S., & Derouin, F. (1994). In vitro model to assess effect of antimicrobial agents on Encephalitozoon cuniculi. Antimicrobial agents and Chemotherapy, 38(10), 2440-2448.
Abstract: We have developed a new micromethod to study the effect of drugs on microsporidia, using MRC5 fibroblasts infected by 10(5) spores of Encephalitozoon cuniculi. After 3 days of incubation with various concentrations of drugs, parasitic foci were counted in stained cultures. The inhibition of microsporidial growth exceeding 90% with albendazole (0.005 microgram/ml), fumagillin (0.001 microgram/ml), 5-fluorouracil (3 micrograms/ml), and sparfloxacin (30 micrograms/ml) was observed. Chloroquine, pefloxacin, azithromycin, and rifabutin were partially effective, at high concentrations. Arprinocid, metronidazole, minocycline, doxycycline, itraconazole, and difluoromethylornithine were not evaluable, since concentrations that inhibited microsporidia were also toxic for fibroblasts. Pyrimethamine, piritrexim, sulfonamides, paromomycin, roxithromycin, atovaquone, and flucytosine were ineffective. Our results confirm that albendazole and fumagillin have marked activity against E. cuniculi and show the antimicrosporidial activity of 5-fluorouracil and sparfloxacin. These data may form the basis for treatment of Encephalitozoon hellem and Septata intestinalis infections and represent an attempt to identify drugs effective against Enterocytozoon bieneusi.

Schottelius, J., Lo, Y., & Schmetz, C. (1995). Septata intestinalis and Encephalitozoon cuniculi: cross-reactivity between two microsporidian species. Folia parasitologica, 42(3), 169-172.
Abstract: An infection with Septata intestinalis was diagnosed in a 35-year-old AIDS patient without diarrhoea. The diagnosis was based on morphological examinations of a duodenal biopsy specimen. Serum antibodies were detected reacting with spores of Encephalitozoon cuniculi. Spores of S. intestinalis and E. cuniculi stained with Brown Hopps Gram stain showed a red colour (Gram negative) and not a blue/black colour which was described for microsporidian spores in tissue. Franssen, F. F., Lumeij, J. T., & Van Knapen, F. (1995). Susceptibility of Encephalitozoon cuniculi to several drugs in vitro. Antimicrobial agents and chemotherapy, 39(6), 1265-1268. Abstract: In the light of the increased incidence of human Encephalitozoon infections and the absence of an established treatment protocol, a simple in vitro testing method to compare activities of drugs against Encephalitozoon cuniculi was developed. With this in vitro method, the 50% inhibitory concentrations of fumagillin, thiabendazole, albendazole, oxibendazole, and propamidine isethionate for E. cuniculi in rabbit kidney cells were determined. Itraconazole, toltrazuril, metronidazole, ronidazole, and ganciclovir were ineffective in this testing Nast, R., Middleton, D. M., & Wheler, C. L. (1996). Generalized encephalitozoonosis in a Jersey wooly rabbit. The Canadian Veterinary Journal, 37(5), 303. [No Abstract Available]

Levkut, M., Lesnik, F., Balent, P., Zajac, V., Korim, P., & Sláviková, K. (1997). Bovine leukemia virus-induced clinical signs and morphological changes of encephalitozoonosis in rabbits. Folia parasitologica, 44(4), 249-254.
Abstract: Fourteen three-month-old rabbits spontaneously-infected with the microsporidium Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 were inoculated intravenously with lymphocytes (Ly) from seropositive bovine leukemia virus infected cattle (Ly/BLV) or with fetal lamb kidney cells infected with bovine fetal leukemia (FLK/BLV). Thirteen rabbits were seropositive to BLV at least for a period of three months. Six rabbits died of pulmonary lesions. Chronic inflammatory lesions of encephalitozoonosis were found in six rabbits killed between 454 and 548 days of the observation period. Five animals bore subcutaneous granulomas. Immunohistochemically, E. cuniculi was demonstrated in the inflammatory lesions of rabbits studied. Control animals also spontaneously infected with E. cuniculi did not show clinical signs of encephalitozoonosis. Morphological changes were found incidentally in the form of small glial foci and focal interstitial nephritis in these animals. The combined action of BLV-E. cuniculi on the bodies of rabbits is proposed as a suitable model for the study of encephalitozoonosis in man with human immunodeficiency virus (HIV) infection.

Mathis, A., Michel, M., Kuster, H., Müller, C., Weber, R., & Deplazes, P. (1997). Two Encephalitozoon cuniculi strains of human origin are infectious to rabbits. Parasitology, 114(1), 29-35.
Abstract: The microsporidian Encephalitozoon cuniculi can infect a wide variety of mammals including man. In this study, E. cuniculi isolates of animal origin were compared with 6 isolates obtained from HIV-infected patients. Based on results of Western blot analysis, random amplified polymorphic DNA (RAPD) and the sequence of the rDNA internal transcribed spacer (ITS) the isolates were classified into 3 groups with the repeated element 5’GTTT-3′ in the ITS being a reliable genetic marker. Five isolates from Swiss patients were found to be homologous to isolates from Swiss rabbits (strain I). The sixth isolate from a patient from Mexico differed by all methods and could be attributed to E. cuniculi strain III that has been described from 2 dogs from the USA. All of these isolates were distinguished from isolates from blue foxes from Norway (strain II). Intraspecific nucleotide divergence of the SSU rRNA gene of E. cuniculi belonging to the 3 strains was in the same low range (0.00-0.15%) as was found for the corresponding sequence of 2 E. hellem isolates. Groups of 2 rabbits were infected by oral inoculation of 10(7) E. cuniculi spores (2 isolates from strain I of human and rabbit origin, 1 from strain III) as shown by antibody responses and the re-isolation of the parasites from brain material. The results provide further evidence that per oral transmission of the parasite between various hosts is feasible.

Feaga, W. P. (1997). Wry neck in rabbits. Journal of the American Veterinary Medical Association, 210(4), 480-480. [No Abstract Available] Thomas, C., Finn, M., Twigg, L., Deplazes, P., & Thompson, R. C. A. (1997). Microsporidia (Encephalitozoon cuniculi) in wild rabbits in Australia. Australian Veterinary Journal, 75(11), 808-810.
Abstract: To determine the prevalence of infection with Encephalitozoon cuniculi in wild rabbit populations in Western Australia, and to isolate the organism from seropositive rabbits. Serological screening of wild and clinically affected domestic rabbit populations. Eighty-one wild rabbits from south-western Western Australia and 29 laboratory rabbits. Indirect immunofluorescence antibody technique and in-vitro amplification of parasite isolates in fibroblast cultures. Of the 81 wild rabbits and 29 laboratory rabbits, 20 and 22 respectively, had antibodies to E cuniculi. E cuniculi from the urine of one seropositive laboratory rabbit and from brain and kidney tissues of eight and five seropositive laboratory and wild rabbits respectively were isolated in fibroblast cultures. E cuniculi infection has been shown for the first time to be prevalent in wild rabbits in Australia. Techniques have been developed for the isolation and culture of the causative agent. Comparative studies can now be undertaken to determine risk factors for clinical disease in domestic rabbits and the relationship among E cuniculi isolates from wild and domestic rabbits.

Levkut, M., Horváth, M., Bálent, P., Levkutová, M., Hipíková, V., & Letková, V. (1997). Catecholamines and encephalitozoonosis in rabbits. Veterinary parasitology, 73(1-2), 173-176.
Abstract: Twenty four rabbits (Oryctolagus cuniculus f. domestica) were used to detect specific anti-Encephalitozoon cuniculi antibodies. To identify microsporidian infection, a haemolytic test in agar gel was carried out. Blood samples of animals with and without spontaneous encephalitozoonosis were evaluated, and compared for the presence of epinephrine (EPI), norepinephrine (NE), and dopamine (DA). Rabbits infected spontaneously with E. cuniculi had significantly lower levels of catecholamines than healthy animals. This decrease in catecholamines is of special interest because of their role as factors modifying the immune response. These neuromediators also have different influences on the function of immune cells.

Leng, L., Štefkovič, M., Révajová, V., Halanová, , & Horváth, M. (1999). Lethal encephalitozoonosis in cyclophosphamide-treated rabbits. Acta Veterinaria Hungarica, 47(1), 85-93.
Abstract: Encephalitozoonosis is an opportunistic infection in animals and humans. Its clinical form is observed in immunosuppressed hosts. We studied the occurrence of the manifest form of rabbit microsporidiosis under cyclophosphamide immunomodulation in 40 New Zealand rabbits. The experimental animals were intraperitoneally infected with 5 x 10(7) Encephalitozoon cuniculi spores. Two weeks after infection the animals were treated intraperitoneally with cyclophosphamide, first with 50 mg/kg and then with 15 mg/kg weekly during the 12-week experimental period. Positive controls were either E. cuniculi-infected or cyclophosphamide-immunosuppressed animals. The negative control rabbits remained untreated. Both clinical signs of encephalitozoonosis and depression of peripheral blood cell count developed between weeks 4 and 6 in the experimental animals which died during week 6 of the experiment. No clinical signs compatible with encephalitozoonosis were observed in any of the controls. The results suggest that immunosuppression induced by cyclophosphamide can give rise to a lethal form of encephalitozoonosis.

Boot, R., Hansen, A. K., Hansen, C. K., Nozari, N., & Thuis, H. C. W. (2000). Comparison of assays for antibodies to Encephalitozoon cuniculi in rabbits. Laboratory animals, 34(3), 281-289.
Abstract: Two indirect immunofluorescence (IIF) assays, two enzyme-linked immunosorbent assays (ELISAs) and the carbon immunoassay (CIA) for determination of antibodies to Encephalitozoon cuniculi were compared using 210 sera of rabbits, 135 of which originated from seven infected colonies, while 75 originated from four uninfected colonies. There was no evidence of a difference between the different assays with respect to the number of positive sera. There was a clear correlation between the quantitative response measured by IIF and CIA and the other assays, and between both IIF tests, while no such correlation was found in the quantitative response measured by ELISAs, which might be explained by the less quantitative nature of the ELISA. Therefore quantitative determination of antibodies to E. cuniculi should be performed by IIF and not by ELISA. The nosographic sensitivities N1 and specificities N2 of the assays were > or = 0.94 and > or = 0.97 respectively. Small differences in N1 and N2 between the assays, although not statistically significant, were responsible for differences in the calculated predictive values of a positive test and of a negative test. As expected, the magnitude of these differences depended on the fraction of positive sera sampled from a given colony. There was strong evidence of such a difference between the fraction of positive sera found in different colonies, but the sample size from some colonies was too small to allow any conclusion, whether this was due to differences in the prevalences of the infection in the colonies or something else. We conclude that any of the assays will be suitable for the routine health monitoring of laboratory rabbit colonies for E. cuniculi infection, as recommended by the Federation of European Laboratory Animal Science Associations.

Sobottka, I., Iglauer, F., Schüler, T., Schmetz, C., Visvesvara, G. S., Albrecht, H., … & Schottelius, J. (2001). Acute and long-term humoral immunity following active immunization of rabbits with inacctivated spores of various Encephalitozoon species. Parasitology research, 87(1), 1-6.
Abstract: Microsporidia of the genus Encephalitozoon are increasingly being reported as a cause of severe, often disseminated infections, mainly in patients with acquired immunodeficiency syndrome (AIDS). Immunological identification of each of the three recognized species (E. cuniculi, E. hellem, and E. intestinalis) requires the availability of specific immune sera. All sera available thus far have been generated by direct inoculation of rabbits with virulent microsporidian spores. This study demonstrates for the first time that subcutaneous immunization with inactivated spores of E. cuniculi, E. helleri, or E. intestinalis is capable of generating highly active rabbit hyperimmune sera to the homologous antigens, with maximal titers being 1:5,120, 1:1,280, and 1:2,560, respectively, as determined by the indirect immunofluorescence technique (IIF). Broad cross-reactivity of the rabbit antisera with all heterologous Encephalitozoon antigens was determined by IIF and immunogold electron microscopy; however, only the E. hellem immune serum strongly cross-reacted with spores of Enterocytozoon bieneusi. During the 35-month follow-up period the antibody titers to the homologous antigens declined to 1:640, 1:160, and 1:320, respectively. The observed decay curves for antibody titers against E. cuniculi, E. hellem, and E. intestinalis were fitted using mathematical modeling, resulting in a predicted duration for specific immune responses of about 7 years on average. Knowledge of the magnitude and duration of specific immune responses is a prerequisite for further evaluation of the concept of using inactivated microsporidian spores in the quest for vaccines against microsporidian infections.

Vivarès CP, Méténier G. (2001). The microsporidian Encephalitozoon. Bioessays. Feb;23(2):194-202.
Abstract: Encephalitozoon cuniculi is an attractive model system for amitochondriate intracellular eukaryotic parasites. It is characterized by a very small genome (below 3 Mbp) and a unique invasion apparatus. Furthermore, as an infectious agent, it is important in human and veterinary medicine. The compactness of its genome involves the reduction of rDNA sequences as well as of some protein-coding genes and intergenic regions. Its highly differentiated apparatus to penetrate the host cell, an extrusome-like polar tube, is composed of novel proteins and may permit various pathways of infestation. Completion of the systematic E. cuniculi sequencing project should provide an important reference system for the comparative genomics of amitochondriate and mitochondriate parasites. Further analysis of orphan genes should help to identify factors that are responsible for its intracellular parasitic way of life.

FURUYA, K., FUKUI, D., YAMAGUCHI, M., NAKAOKA, Y., BANDO, G., & KOSUGE, M. (2001). Isolation of Encephalitozoon cuniculi using primary tissue culture techniques from a rabbit in a colony showing encephalitozoonosis. Journal of Veterinary Medical Science, 63(2), 203-206.
Abstract: Encephalitozoon spores were isolated in a primary tissue culture of the kidneys from an encephalitozoonosis-suspected rabbit in a municipal zoo in Hokkaido. The isolated spores were morphologically characteristic of microsporidial ones in chromotrope stain, and proven to be E. cuniculi by a polymerase chain reaction (PCR) with a species-specific primer set and by direct DNA sequencing of the PCR products.

Suter, C., Müler-Doblies, U. U., Deplazes, P., & Hatt, J. M. (2001). Prevention and treatment of Encephalitozoon cuniculi infection in rabbits with fenbendazole. Veterinary Record, 148(15), 478-480.
Abstract: The efficacy of fenbendazole for preventing an experimental infection of Encephalitozoon cuniculi and for eliminating the spores from the central nervous system of naturally infected rabbits was investigated. Fenbendazole (20 mg/kg bodyweight daily) was administered from seven days before until two or 21 days after rabbits had been infected orally with 10(6) spores of E. cuniculi. Both regimens were effective in preventing the establishment of the parasites, as demonstrated by negative parasitic-specific serology and by the failure to isolate the parasite from brain tissue. In naturally infected, seropositive rabbits, parasites were successfully isolated from seven of nine untreated animals, but not from the brain tissue of eight animals treated with fenbendazole-medicated pellets for four weeks.

Keeble E. (2001). Encephalitozoon cuniculi in rabbits. Vet Rec. Dec 1;149(22):688.
[No Abstract Available]

Boot, R. (2002). Serologic test in rabbits with Encephalitozoon cuniculi infection. Tijdschrift voor diergeneeskunde, 127(13), 426.
[No Abstract Available]

Furuya, K. (2002). Genotyping of Encephalitozoon cuniculi isolates found in Hokkaido. Japanese journal of infectious diseases, 55(4), 128-130.
[No Abstract Available]

Furuya, K. (2002). Genotyping of Encephalitozoon cuniculi isolates found in Hokkaido. Japanese journal of infectious diseases, 55(4), 128-130.
Abstract: Spores of Encephalitozoon cuniculi, E. hellem, and E. intestinalis harvested from cultured mammalian cells were suspended in deionized water, exposed to gamma irradiation at doses of 0-3.0 kGy, and then tested for infectivity by inoculating spores into monolayer cultures of Madin-Darby bovine kidney cells. The cultures were examined for developing microsporidia 4 days later. As the dosage level of radiation increased, corresponding decreases were observed in the number of developing microsporidia for all 3 species. For E. cuniculi and E. intestinalis, 100% inhibition of development was observed after exposure to 1.5 and 2.0 kGy, respectively. Although development of E. hellem was greatly inhibited (97.6% inhibition) after exposure to 3.0 kGy, complete inhibition was not obtained. These findings provide a baseline for investigating the dose levels required to render food products safe when kept under varying temperature, moisture, and other storage conditions.

Felchle, L. M., & Sigler, R. L. (2002). Phacoemulsification for the management of Encephalitozoon cuniculi‐induced phacoclastic uveitis in a rabbit. Veterinary ophthalmology, 5(3), 211-215.
Abstract: Phacoemulsification was performed on a New Zealand White rabbit with slowly progressive unilateral phacoclastic uveitis and cataract formation. The irrigating solution with lenticular contents were centrifuged and examined cytologically using Weber’s chromotrope-based stain. Microsporidial spores were observed and positively identified as Encephalitozoon cuniculi via polymerase chain reaction. More than 1 year following surgical therapy, the rabbit is visual and comfortable without medications.

Halanova, M., Cislakova, L., Valencakova, A., Balent, P., Adam, J., & Travnicek, M. (2003). Serological screening of occurrence of antibodies to Encephalitozoon cuniculi in humans and animals in Eastern Slovakia. Annals of agricultural and environmental medicine: AAEM, 10(1), 117-120.
Abstract: Encephalitozoon cuniculi is one of the mamalian microsporidian pathogens that can affect a number of different species of animals as well as humans. The presence of specific serum antibodies to Encephalitozoon cuniculi was studied in a group of animals and humans from Eastern Slovakia by the indirect immunofluorescence of antibodies (IFA). 456 people, 571 rabbits, 457 mice, 193 dogs, 72 cats, and 59 sheep were examined. Specific anti-E. cuniculi antibodies were found in 26 out of 456 human sera examined (5.7%). The highest occurrence of antimicrosporidial antibodies was found in the group of immunodeficiency patients – 37.5%. In the group of animals, the highest positivity was observed in rabbits – 41.7%, and in dogs – 37.8. The relative high prevalence, especially in rabbits and dogs as potential sources of microsporidial infection for humans, indicates the importance of performing the screening examinations in animals with aim of reducing or halting the spread of this disease.

Johnson, C. H., Marshall, M. M., DeMaria, L. A., Moffet, J. M., & Korich, D. G. (2003). Chlorine inactivation of spores of Encephalitozoon spp. Appl. Environ. Microbiol., 69(2), 1325-1326.
Abstract: This report is an extension of a preliminary investigation on the use of chlorine to inactivate spores of Encephalitozoon intestinalis and to investigate the effect of chlorine on two other species, E cuniculi and E. hellem, associated with human infection. The 50% tissue culture infective doses of these three species were also determined. On the basis of the results obtained, it appears that chlorination of water is an effective means of controlling spores of these organisms in the aquatic environment.

Baneux, P. J. R., & Pognan, F. (2003). In utero transmission of Encephalitozoon cuniculi strain type I in rabbits. Laboratory animals, 37(2), 132-138.
Abstract: Pregnant rabbits were serologically diagnosed as having been infected with Encephalitozoon cuniculi. At necropsy at 28 days of gestation, does, placentas and fetuses were found to be infected with E. cuniculi strain type I as evidenced by using the nested-polymerase chain reaction (PCR) technique, thereby confirming vertical transplacental transmission.

Harcourt-Brown, F. M., & Holloway, H. K. R. (2003). Encephalitozoon cuniculi in pet rabbits. Veterinary Record, 152(14), 427-431.
Abstract: The results of a serological test for Encephalitozoon cuniculi in 125 pet rabbits are reviewed, together with follow-up studies of clinical cases. Blood samples were taken from 38 asymptomatic rabbits and 87 rabbits showing neurological, renal or ocular signs suggestive of encephalitozoonosis. In the asymptomatic group, six of 26 (23 per cent) apparently healthy rabbits, sampled as part of a health screen, were seropositive; of the remaining 12 asymptomatic rabbits, sampled because they lived with seropositive companions, eight (66 per cent) were seropositive. Fifty-eight of the rabbits with clinical disease showed neurological signs, including head tilt, seizures, ataxia and swaying; three of them also showed renal signs and two showed ocular signs, and these five rabbits were all seropositive. Head tilt was the most common neurological sign in 21 of 23 (91 per cent) of the seropositive cases. All nine rabbits with ocular lesions were seropositive. In follow-up studies of clinical cases, the rabbits showed variable responses to treatment with albendazole, fenbendazole, antibiotics or corticosteroids, and some cases recovered without treatment.

Leiro, J., Cano, E., Ubeira, F. M., Orallo, F., & Sanmartín, M. L. (2004). In vitro effects of resveratrol on the viability and infectivity of the microsporidian Encephalitozoon cuniculi. Antimicrobial agents and chemotherapy, 48(7), 2497-2501.
Abstract: Microsporidians of the genus Encephalitozoon are an important cause of disease in immunocompromised patients, and there are currently no completely effective treatments. The present study investigated the viability and infectivity of spores of Encephalitozoon cuniculi that had been exposed to resveratrol (RESV), a natural phytoalexin found in grapes and red wine. RESV at 50 microM showed significant sporicidal activity, and at 10 to 50 microM it reduced the capacity of the spores to infect dog kidney epithelial cells of the MDCK line. At 10 microM RESV also significantly inhibited intracellular development of the parasite, without affecting host cell viability. These results suggest that RESV may be useful in the treatment of Encephalitozoon infections.

Mo, L., & Drancourt, M. (2004). Monoclonal antibodies for specific detection of Encephalitozoon cuniculi. Clin. Diagn. Lab. Immunol., 11(6), 1060-1063.
Abstract: Seven species-specific monoclonal antibodies (MAbs) were produced against Encephalitozoon cuniculi and characterized. The MAbs were immunoglobulin G, and when used for indirect microimmunofluorescence microscopy and Western immunoblot assays, they detected E. cuniculi originating from clinical samples. They did not cross-react with other Encephalitozoon species (E. intestinalis and E. hellem) or with a collection of gram-negative bacteria, yeast, and other parasites. The MAbs reacted primarily with 121-, 56-, 45-, 43-, and 41-kDa protein epitopes of E. cuniculi. These epitopes were demonstrated to be E. cuniculi species specific by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We developed MAbs to strains of E. cuniculi that can be used successfully to distinguish E. cuniculi from other microsporidial species in cultures established from clinical specimens. These MAbs may provide a specific, simple, rapid, and low-cost tool for the identification and diagnosis of infections due to microsporidia.

Franzen, C., Müller, A., Hartmann, P., & Salzberger, B. (2005). Cell invasion and intracellular fate of Encephalitozoon cuniculi (Microsporidia). Parasitology, 130(3), 285-292.
Abstract: Microsporidia are obligate intracellular parasites that utilize a unique mechanism to infect host cells, which is one of the most sophisticated infection mechanisms in biology. Microsporidian spores contain a long coiled polar tube that extrudes from the spores and penetrates the membranes of new host cells. We have initiated a study to investigate the invasive process and intracellular fate of the microsporidium Encephalitozoon cuniculi. Here we show that relatively few cells were infected through the traditional penetration of the polar tube from outside. Rather, phagocytosis of spores occurred at least 10 times more frequently than injection of sporoplasms. Some spores extruded their polar tube inside the cells following phagocytosis. Membranes of the vacuoles surrounding the internalized spores were positive for late endosomal and lysosomal markers. Spores that remained inside these compartments disappeared within 3 days. Thus, our studies demonstrate that in addition to the unique way in which microsporidia infect host cells, E. cuniculi spores can also gain access to host cells by phagocytosis. The presence of intracellular spores that have extruded their polar tube shows that some spores germinate after phagocytosis, thus escaping from the phagosomes that mature into lysosomes.

Giordano, C., Weigt, A., Vercelli, A., Rondena, M., Grilli, G., & Giudice, C. (2005). Immunohistochemical identification of Encephalitozoon cuniculi in phacoclastic uveitis in four rabbits. Veterinary ophthalmology, 8(4), 271-275.
Abstract: Encephalitozoon cuniculi is a microsporidium with a wide range of mammalian hosts. In rabbits it can be responsible for cataract and lens-induced uveitis (LIU). The aim of this study was to provide specific immunohistochemical demonstration and localization of E. cuniculi within the eye, in rabbits with LIU.
Four rabbits were presented with a white mass in the eye and iris discoloration. Complete ophthalmic examinations were performed and a presumptive diagnosis of LIU was made in all cases. Initial therapy with a topical steroid, atropine and systemic enrofloxacin was instituted while serologic (IFA or ICA tests) and cytologic lab results were pending. The final outcome in all cases was enucleation. Routine histology and immunohistochemistry (ABC method) with an antiserum anti-Encephalitozoon cuniculi were performed. Indirect immunofluorescence performed on one rabbit serum expressed a titer of 1 : 32; carbon immunoassay on the serum of the other three rabbits expressed a titer of 1 : 5120 in one, and a titer of 1 : 2560 in the other two cases. Histologically, an intraocular, locally extensive pyogranulomatous infiltration that partially filled the posterior chamber, encasing a wide anterior lens capsule break, was detected in all cases. Immunohistochemically, spores reacting with anti-Encephalitozoon cuniculi antiserum were present in all specimens, occasionally within macrophages and lens epithelial cells. Detection of E. cuniculi in rabbits with phacoclastic uveitis has been investigated in the past with different methods. Based on our results, we suggest that immunohistochemistry should be regarded as a useful tool both for specific demonstration of E. cuniculi and for its localization within tissues.

Jordan, C. N., Zajac, A. M., Snowden, K. S., & Lindsay, D. S. (2006). Direct agglutination test for Encephalitozoon cuniculi. Veterinary Parasitology, 135(3-4), 235-240.
Abstract: Encephalitozoon cuniculi is a small protozoan parasite in the phylum Microspora. It has been shown to naturally infect several host species, including humans. Infection with microsporidia is usually asymptomatic, except in young or immunocompromised hosts. Currently, serological diagnosis of infection is made using the indirect immunofluorescent antibody assay (IFA) or enzyme-linked immunosorbent assay (ELISA). Although these methods are sensitive and reliable, there are several drawbacks to the IFA and ELISA tests. Cross-reactivity between other Encephalitozoon species is common, and specialized equipment is required to conduct these tests. This paper reports the development of a direct agglutination test for detecting IgG antibodies to E. cuniculi. The utility of the agglutination test was examined in CD-1 and C3H/He mice infected with E. cuniculi or one of 2 other Encephalitozoon species. Test sera were incubated overnight with eosin-stained microsporidia spores in round-bottom microtiter plates. In positive samples, agglutination of spores with antibodies in test sera resulted in an opaque mat spread across the well. The results indicate that the agglutination test is 86% sensitive and 98% specific for E. cuniculi, with limited cross-reactivity to Encephalitozoon intestinalis. No cross-reactivity to Encephalitozoon hellem was observed. The test is fast and easy to conduct, and species-specific antibodies are not required.

Jordan, C. N., DiCristina, J. A., & Lindsay, D. S. (2006). Activity of bleach, ethanol and two commercial disinfectants against spores of Encephalitozoon cuniculi. Veterinary parasitology, 136(3-4), 343-346.
Abstract: Encephalitozoon cuniculi is a small protist parasite in the phylum Microspora. Hosts are infected by ingestion or inhalation of spores passed in the urine or feces. Infection with E. cuniculi is usually asymptomatic, except in young or immunocompromised hosts. This study examined the effects of various disinfectants on in vitro infectivity of E. cuniculi spores. Spores of E. cuniculi were exposed to several dilutions of commercial bleach, 70% ethanol and dilutions of commercial disinfectants HiTor and Roccal for 10 min and then loaded onto human fibroblast cells (Hs68 cells). Ten minutes of exposure to these disinfectants was lethal to E. cuniculi spores. Additional exposure time studies were done using dilutions of bleach at 0.1, 1 and 10%, and 70% ethanol. Exposure of E. cuniculi spores to 1 or 10% bleach for 30s rendered them non-infectious for Hs68 cells. Growth of E. cuniculi was observed in Hs68 cells inoculated with spores treated with 0.1% bleach for 30s or 1, 3 and 5 min, but not with spores treated for 7 min or longer. Exposure of E. cuniculi spores to 70% ethanol for 30s rendered them non-infectious for Hs68 cells. Spores of E. cuniculi are more sensitive to disinfectants than are coccidial oocysts and other parasite cysts. The relatively short contact time needed to kill spores indicates that disinfection of animal housing may be a viable means to reduce exposure of animals to E. cuniculi spores.

Keeble, E. J., & Shaw, D. J. (2006). Seroprevalence of antibodies to Encephalitozoon cuniculi in domestic rabbits in the United Kingdom. Veterinary Record, 158(16), 539-544.
Abstract: Serum samples from 97 clinically healthy domestic rabbits were tested for antibodies to Encephalitozoon cuniculi by an indirect elisa technique. Fifty (52 per cent) of them were seropositive. The samples were taken as part of a routine health screen or before general anaesthesia at 22 veterinary practices in England, Scotland and Wales, and the veterinary surgeons were asked to complete a questionnaire to provide information concerning the animal’s husbandry, diet, vaccination, health status and any preventive medicine routines. None of these factors was found to be associated with the serological status of the rabbits.

Brosson, D., Kuhn, L., Delbac, F., Garin, J., P. Vivarès, C., & Texier, C. (2006). Proteomic analysis of the eukaryotic parasite Encephalitozoon cuniculi (microsporidia): a reference map for proteins expressed in late sporogonial stages. Proteomics, 6(12), 3625-3635.
Abstract: The microsporidian Encephalitozoon cuniculi is a unicellular obligate intracellular parasite considered as an emerging opportunistic human pathogen. The differentiation phase of its life cycle leads to the formation of stress-resistant spores. The E. cuniculi genome (2.9 Mbp) having been sequenced, we undertook a descriptive proteomic study of a spore-rich cell population isolated from culture supernatants. A combination of 2-DE and 2-DE-free techniques was applied to whole-cell protein extracts. Protein identification was performed using an automated MALDI-TOF-MS platform and a nanoLC-MS/MS instrument. A reference 2-DE map of about 350 major spots with multiple isoforms was obtained, and for the first time in microsporidia, a large set of unique proteins (177) including proteins with unknown function in a proportion of 25.6% was identified. The data are mainly discussed with reference to secretion and spore structural features, energy and carbohydrate metabolism, cell cycle control and parasite survival in the environment.

Taupin, V., Méténier, G., Vivarès, C. P., & Prensier, G. (2006). An improved procedure for Percoll gradient separation of sporogonial stages in Encephalitozoon cuniculi (Microsporidia). Parasitology research, 99(6), 708-714.
Abstract: Intracellular development of microsporidian parasites comprises a proliferative phase (merogony) followed by a differentiation phase (sporogony) leading to the release of resistant spores. Sporogony implies, successively, meront-to-sporont transformation, sporont division into sporoblasts, and sporogenesis. We report a procedure improving the separation of sporogonial stages of Encephalitozoon cuniculi, a species that develops inside parasitophorous vacuoles of mammalian cells. Supernatants of E. cuniculi-infected Madin-Darby canine kidney cell cultures provided a large number of parasites mixed with host-cell debris. This material was gently homogenized in phosphate-buffered saline containing 0.05% saponin and 0.05% Triton X-100 then filtered through glass wool columns. Centrifugation of the filtrate on 70% Percoll-0.23 M sucrose gradient gave a reproducible pattern of bands at different densities. Transmission electron microscopy showed that three of the four collected fractions were free of visible contaminants. Corresponding prominent cell stages were early sporoblasts (fraction B), late sporoblasts plus immature spores (fraction C), and mature spores (fraction D). Further centrifugation of the lightest fraction (A) on 30% Percoll-0.23 M sucrose gradient generated a sporont-rich fraction (A2). First analysis of proteins from fractions A2 and D by two-dimensional gel electrophoresis suggested a potential use of the described method for proteomic profiling.

Harcourt-Brown, F. (2007). Radiographic signs of renal disease in rabbits. Veterinary Record, 160(23), 787-794.
Abstract: The radiological features of 65 rabbits with suspected renal disease are reviewed. The radiological features included a generalised increase in bone opacity (osteosclerosis), renomegaly, nephroliths, ureteroliths and soft tissue mineralisation. One or more of these changes were present on radiographs of 57 of the 65 rabbits. Renal disease was suspected because of the clinical signs and the presence of kidney stones and/or high blood concentrations of urea and creatinine. Significant renal disease was confirmed in 14 cases that were examined postmortem. Blood urea and creatinine concentrations were measured in 47 cases but not all the rabbits had high levels of both. Blood calcium concentration was high in 33 of the 38 rabbits in which it was measured. Serum phosphate was high in 17 and low in five of 34 rabbits in which it was measured. Hyperphosphataemia was associated with generalised osteosclerosis and aortic calcification. Rabbits with osteosclerosis were thin, depressed and unwilling to move. Thirty-eight of 41 rabbits that were tested were seropositive for antibodies to Encephalitozoon cuniculi. Histological lesions suggestive of E cuniculi infection were found in all 13 cases that were examined postmortem, although the organisms were visible in only one case.

Künzel, F., Gruber, A., Tichy, A., Edelhofer, R., Nell, B., Hassan, J., … & Joachim, A. (2008). Clinical symptoms and diagnosis of encephalitozoonosis in pet rabbits. Veterinary parasitology, 151(2-4), 115-124.
Abstract: Infections with Encephalitozoon cuniculi in rabbits are observed at increasing frequency and are known as opportunistic infections in immunocompromised humans. 191 pet rabbits with suspected encephalitozoonosis, presented at the Animal Hospital of the Veterinary University of Vienna (Austria), were included in this study. Rabbits were serologically examined for antibodies against E. cuniculi (144 positive out of 184 rabbits with suspected encephalitozoonosis compared to 14 positive out of 40 clinically healthy rabbits tested as part of a standard health check) and Toxoplasma gondii (8 positive out of 157). Of the 144 seropositive rabbits with clinical signs, 75% showed neurological symptoms, 14.6% demonstrated phacoclastic uveitis and 3.5% suffered from renal failure. 6.9% of the animals had combined symptoms. Vestibular disease dominated within the rabbits that showed neurological symptoms. Polymerase chain reaction (PCR) could not detect parasite DNA in urine or cerebrospinal fluid (CSF), but did so in 4 out of 5 samples of liquefied lens material in cases with phacoclastic uveitis due to lens capsule rupture. Additionally further diagnostic procedures, such as inspection of the external ear canal (N=69), radiography of the tympanic bullae (N=65) were performed to rule out differential diagnosis. 54.2% of the patients exhibiting neurological symptoms recovered within a few days, while 87.5% of the rabbits suffering from renal failure died or had to be euthanized.

Okewole, E. A. (2008). Seroprevalence of antibodies to Encephalitozoon cuniculi in domestic rabbits in Nigeria. Onderstepoort Journal of Veterinary Research, 75(1), 33-38.
Abstract: Serum samples from 237 randomized rabbits from the five ecological zones of Nigeria, i.e. Northwest (NW), Northeast (NE), Southeast (SE), Southwest (SW) and Northcentral (NC), were evaluated for the presence of antibodies to Encephalitozoon cuniculi by the indirect immunofluorescent antibodies test. A titre of 10 or more was taken as positive. Thirty-nine (16.5%) of the 237 samples were positive with 11, 10, 8, 6 and 4 seropositive rabbits occurring in the NW, NE, SE, SW and NC zones of Nigeria, respectively. Age, sex, live mass and access to grass as a feed supplement were not statistically (P > 0.05) associated with seropositivity, but cage type (single-versus multi-rabbit type), contact with free-range rats and previous illness were strongly (P < 0.05) associated with it. The practice of selling unscreened and untreated 5 to 10-week-old weaners to prospective buyers as foundation stock, use of multi-rabbit communal cages, occasional release of rabbits in runs and contact with free-range house rats should be discouraged. Regular prophylactic and curative treatments, occasional serological screening to remove carriers, and the practice of a high level of hygiene in rabbit colonies are effective control measures.

Dipineto, L., Rinaldi, L., Santaniello, A., Sensale, M., Cuomo, A., Calabria, M., … & Fioretti, A. (2008). Serological survey for antibodies to Encephalitozoon cuniculi in pet rabbits in Italy. Zoonoses and public health, 55(3), 173-175.
Abstract: Pet rabbits (n = 125) from Southern Italy were submitted to a serological screening for Encephalitozoon cuniculi, using an enzyme-linked immunosorbent assay (ELISA) and a carbon immunoassay (CIA). Seventy-eight examined rabbits showed clinical signs suggestive of encephalitozoonosis (head tilt, ataxia, paralysis, cataracts, uveitis, polyuria and polydipsia), whereas 47 were healthy rabbits. Antibodies anti-E. cuniculi were found in 84/125 (67.2%) sera analysed. The results of the chi-squared test showed that sex and health status had no significant effect (P > 0.05) on E. cuniculi seropositivity; however, rabbits older than 4 months had a seropositivity for E. cuniculi significantly (P < 0.05) higher than that of rabbits aged up to 4 months. The results of the present survey reinforce the assumption that rabbit may be indicated as the main reservoir of E. cuniculi; therefore, routine screening examinations in pet rabbits are strongly advised considering the zoonotic potential of this parasite.

Valencakova, A., Balent, P., Petrovova, E., Novotny, F., & Luptakova, L. (2008). Encephalitozoonosis in household pet Nederland Dwarf rabbits (Oryctolagus cuniculus). Veterinary parasitology, 153(3-4), 265-269.
Abstract: The paper presents the results of examination of 32 domestically bred rabbits, the breed Nederland Dwarf of Oryctolagus cuniculus, for the presence of Encephalitozoon cuniculi microsporidian species. The results of serological tests for E. cuniculi in 32 rabbits are reviewed along with other follow-up studies of clinical cases. Blood samples were taken from 7 asymptomatic rabbits and 25 rabbits showing neurological and ocular signs suggestive of encephalitozoonosis. In the asymptomatic group, 5 out of 7 rabbits were seropositive (71%). 16 rabbits with clinical diseases showed neurological sings, including torticollis, circus-like movements, loss of weight; 6 of them also showed ataxia, anorexia, asthenia of hind-limbs and 3 showed ocular signs. All 25 rabbits were seropositive. The spores of E. cuniculi were isolated from the faecal samples or kidneys and brain of an animal and subsequently were used for DNA isolation and PCR analysis.

Jass, A., Matiasek, K., Henke, J., Küchenhoff, H., Hartmann, K., & Fischer, A. (2008). Analysis of cerebrospinal fluid in healthy rabbits and rabbits with clinically suspected encephalitozoonosis. Veterinary Record, 162(19), 618-622.
Abstract: Samples of uncontaminated cerebrospinal fluid (csf) were collected from the cisterna magna of 20 healthy laboratory rabbits and 21 pet rabbits with vestibular disease and/or paresis due to clinically suspected encephalitozoonosis. In the healthy rabbits’ csf the leucocyte count was <or=4 leucocytes/microl (median 1.5 microl) and the concentration of protein ranged from 0.13 to 0.31 g/l (median 0.24 g/l). In the diseased rabbits, the number of leucocytes ranged from 1 to 87/microl (median 15/microl; P<0.001), and the concentration of protein ranged from 0.31 to 1.54 g/l (median 0.79 g/l; P<0.001); a cytological evaluation showed that they had greater numbers of lymphocytes and monocytes. It was concluded that encephalitozoonosis in rabbits is characterised by lymphomonocytic pleocytosis in CSF.

Igarashi, M., Oohashi, E., Dautu, G., Ueno, A., Kariya, T., & Furuya, K. (2008). High seroprevalence of Encephalitozoon cuniculi in pet rabbits in Japan. Journal of Veterinary Medical Science, 70(12), 1301-1304.
Abstract: Infection with Encephalitozoon cuniculi in rabbits frequently exists as a chronic, latent infection, and only a percentage of infected animals develop clinical disease. This study presents a seroepidemiological study of E. cunicucli infection in 337 pet rabbits collected from 20 prefectures in Japan in 2006 and 2007, using enzyme-linked immunosorbent assay (ELISA) capable of measuring IgG and IgM antibodies. These rabbits were divided into the following four groups: healthy and isolated rabbits (n=74, group I), healthy and companioned rabbits (n=121, group II), neurologically diseased rabbits (n=105, group III), and other diseased rabbits (n=37, group IV). Using ELISA for IgG antibodies, the highest detection rate, 81%, was seen in group III, the second highest, 75.2%, in group II, and the lowest, 29.7%, in group I, which was significantly different to the other groups except for group IV (43.2%). On the other hand, when ELISA was used for IgM antibody detection, 14-40% of rabbits in the four groups were also observed to have anti-E. cuniculi IgM. This study demonstrated high seroprevalence of E. cuniculi in not only neurologically diseased rabbits but also healthy and other diseased rabbits.

Csokai, J., Gruber, A., Künzel, F., Tichy, A., & Joachim, A. (2009). Encephalitozoonosis in pet rabbits (Oryctolagus cuniculus): pathohistological findings in animals with latent infection versus clinical manifestation. Parasitology research, 104(3), 629-635.
Abstract: Encephalitozoon cuniculi is a common infectious agent of rabbits. The aim of this study was to determine the distribution and extent of histological lesions in the brain and in the kidney of naturally infected pet rabbits with or without clinical encephalitozoonosis. In 71 animals (33 with symptoms) which died or were euthanised, histopathological examination including staining of spores (Ziehl-Neelsen, acid-fast trichrome) was performed and changes were described quantitatively. The cerebrum was the most frequently affected brain region (97.5%), whilst the cerebellum (55%) and the vestibular cores (37.5%) were less commonly concerned. Granulomas were found in 77.5% of animals with encephalitis and in 12.5% of rabbits with interstitial nephritis. Although cerebral granulomas were found irrespective of the grade of histological changes, they were significantly correlated with changes at higher grades. There was no correlation between the severity of encephalitis and neurological symptoms. Since severe lesions were also found in clinically inconspicuous animals, histological findings of inflammatory lesions are not indicative of overt encephalitozoonosis as the causative agent for neurological signs. Other diseases causing neurological symptoms, such as suppurative encephalitis, otitis media as well as malignant lymphoma were also detected in the rabbit population that was examined in the present study.

Reusch, B., Murray, J. K., Papasouliotis, K., & Redrobe, S. P. (2009). Urinary protein: creatinine ratio in rabbits in relation to their serological status to Encephalitozoon cuniculi. Veterinary Record, 164(10), 293-295.
Abstract: The concentrations of protein and creatinine were measured in urine samples from 74 healthy domestic pet rabbits, 54 of them seronegative to Encephalitozoon cuniculi and 20 seropositive. The calculated reference range for the urinary protein:creatinine ratio (UPC) of E cuniculi-seronegative rabbits was 0.11 to 0.40. There was no significant variation in the UPC due to the bodyweight, breed, sex, neutered status or husbandry of the rabbits. Seroconversion to E cuniculi was not found to be associated with clinical renal disease because none of the seropositive rabbits had azotaemia or proteinuria.

Cray, C., Arcia, G., Schneider, R., Kelleher, S. A., & Arheart, K. L. (2009). Evaluation of the usefulness of an ELISA and protein electrophoresis in the diagnosis of Encephalitozoon cuniculi infection in rabbits. American journal of veterinary research, 70(4), 478-482.
Abstract: To evaluate the usefulness of an antibody detection ELISA and protein electrophoresis (PE) for diagnosing Encephalitozoon cuniculi (ECUN) infection in pet rabbits. ANIMALS-203 pet rabbits. PROCEDURES-Serum and plasma samples from pet rabbits were submitted from veterinary clinics within the United States. Participating veterinarians completed a questionnaire that was used to classify rabbits as clinically normal (n=33), suspected of having an ECUN infection (103), or clinically abnormal but not suspected of having an ECUN infection (67). An ELISA for detection of serum or plasma IgG against ECUN was developed by use of commercially available reagents. Results of the ELISA and PE were used to detect ECUN infection. RESULTS-A high seroprevalence of antibody against ECUN was detected in all 3 groups of rabbits. In rabbits suspected of having an ECUN infection, the mean IgG titer was 1.7 times as high as the values in the other rabbit groups. Rabbits suspected of having an ECUN infection and those that were simply clinically abnormal had a higher concentration of gamma-globulins than clinically normal rabbits. This increase in globulins concentration was accompanied by a decrease in the albumin-to-globulin ratio. Results of the ELISA and PE were significantly different between clinically normal rabbits and those suspected of having an ECUN infection. CONCLUSIONS AND CLINICAL RELEVANCE-The combination of an ELISA and PE may aid in the diagnosis of ECUN infection in pet rabbits. IMPACT FOR HUMAN MEDICINE-Because ECUN is a potential zoonotic agent, diagnostic methods for pet rabbits need to be improved to protect human health.

Furuya, K. (2009). Spore-forming microsporidian encephalitozoon: current understanding of infection and prevention in Japan. Jpn J Infect Dis, 62(6), 413-22.
Abstract: Microsporidia are spore-forming obligate intracellular parasites. They are known to cause opportunistic infections in humans through zoonotic, waterborne and foodborne transmission routes. This article reviews the present knowledge regarding microsporidian Encephalitozoon cuniculi infections in animals living in the human environment in Japan and discusses the basic measures required for the effective disinfection of Encephalitozoon. The article also discusses seroepidemiologic data from healthy people in order to shed light on the mechanisms of protective immunity and to identify potential strategies for preventive medicine.

Künzel, F., & Joachim, A. (2010). Encephalitozoonosis in rabbits. Parasitology research, 106(2), 299-309.
Abstract: Encephalitozoon cuniculi is an obligatory intracellular microsporidian parasite that can infect a wide range of mammals, including rodents, rabbits, horses, carnivores and humans, in which the organism is known as an opportunistic pathogen of immunocompromised individuals. Nevertheless, the main host for E. cuniculi is the rabbit and infections usually have a sub-clinical course. However, severe disease is recognised in pet rabbits more frequently within the last years. As the central nervous system, the kidney and the eye are predilection organs for the organism, predominant histopathological alterations comprise granulomatous meningoencephalitis, chronic interstitial nephritis and phacoclastic uveitis. A definitive diagnosis of encephalitozoonosis in vivo is difficult, but it is important for specific treatment and the determination of possible zoonotic risks. This review article covers epidemiology, pathology, pathophysiology, immunology, clinical signs, differential diagnosis, diagnosis and treatment of encephalitozoonosis in rabbits.

Jeklova, E., Jekl, V., Kovarcik, K., Hauptman, K., Koudela, B., Neumayerova, H., … & Faldyna, M. (2010). Usefulness of detection of specific IgM and IgG antibodies for diagnosis of clinical encephalitozoonosis in pet rabbits. Veterinary parasitology, 170(1-2), 143-148.
Abstract: Encephalitozoon cuniculi is an obligate intracellular pathogen that has wide host distribution, but primary affects rabbits. This study presents a seroepidemiological study of E. cuniculi infection in 500 pet rabbits from the Czech Republic using ELISA capable of measuring IgM and IgG antibodies. Specific IgM antibodies, reflecting acute, reactivated infection or reinfection, were detected in 32.4% of all rabbits. IgG antibodies indicating chronic infection, were presented in 68.0% of all rabbits. The highest detection rate of IgM (54.4%) and IgG (86.1%) antibodies was ascertained in rabbits with neurological symptoms (n=79, group I). In rabbits with renal disorders (n=47, group II) 36.2% animals were specific IgM and 80.9% IgG positive. Out of 9 rabbits with ocular disorders (group III), 44.4% were positive for anti-E. cuniculi IgM and 77.8% for IgG antibodies. In rabbits with multiple signs (neurological and renal or ocular, n=16, group IV), 43.8% animals were specific IgM and 68.8% IgG positive. Out of 287 rabbits with other disease (group V), 26.5% were positive for anti-E. cuniculi IgM and 64.1% for IgG antibodies. However, the high presence of IgM (24.2%) and IgG (51.6%) antibodies was detected in clinically healthy rabbits (n=62, group VI). Toxoplasma gondii infection should be considered as a differential diagnosis for neurological and ocular disorders in rabbits. Using ELISA, 19.2% from all rabbits were positive for specific anti-T. gondii IgG. The highest seropositivity was detected in group III (44.4%). Simultaneous testing of IgM and IgG specific antibodies give an indication of the infection status. Presence of IgM antibodies is indicative for active infection with requirement to institute proper antimicrosporidial therapy. As active infection was detected in considerably high numbers of rabbits with clinical signs that are not usually associated with E. cuniculi, and even in asymptomatic rabbits, detection of both isotypes of specific antibodies should be a routine part of a health check in rabbits.

Lewis, W. (2010). Exposure to Encephalitozoon cuniculi in rabbits with dental disease. The Veterinary Record, 166(23), 730.
[No Abstract Available]

Jeklova, E., Leva, L., Kovarcik, K., Matiasovic, J., Kummer, V., Maskova, J., … & Faldyna, M. (2010). Experimental oral and ocular Encephalitozoon cuniculi infection in rabbits. Parasitology, 137(12), 1749-1757.
Abstract: Encephalitozoon cuniculi is an obligate intracellular pathogen that has a wide host distribution, but primarily affects rabbits. The aim of this study was to characterize both the cell-mediated and the antibody response in rabbits after experimental infection using 2 different infection routes: oral and ocular. SPF rabbits were infected with low (10³ spores) and high (107 spores) infection doses. Monitored parameters included clinical signs, detection of spores in urine, antibody response detected with ELISA, and cell-mediated immunity detected by antigen-driven lymphocyte proliferation. At week 13 post-infection, half of the rabbits in each group were suppressed by intramuscular administration of dexamethasone. At week 18 post-infection, animals were euthanized. Clinical signs were mild with exacerbation after immunosuppression. Spores in urine and antigen-specific cell-mediated immunity were detected from weeks 5 and 4 post-infection, respectively. Specific IgM was detected 1 week after infection, and IgG antibodies followed 1 week later in rabbits infected with the high dose. Immunological responses were dose dependent. The authors can conclude that both oral and ocular experimental infection with E. cuniculi resulted in an immune response of the infected animals. Rabbits could be used as an experimental model for the study of ocular microsporidiosis.

Ozkan, O., Ozkan, A. T., & Zafer, K. (2011). Encephalitozoonosis in New Zealand rabbits and potential transmission risk. Veterinary parasitology, 179(1-3), 234-237.
Abstract: Encephalitozoon cuniculi is a small protozoan parasite in the phylum Microspora. It has been shown to naturally infect several host species, including humans. Encephalitozoonosis is routinely diagnosed in vivo by serological examination or post mortem by histopathology. In a conventional rabbit colony, two animals suddenly showed clinical signs (torticollis and asthenia of limbs). Serum samples of these rabbits were seropositive for E. cuniculi after definitive diagnosis (Toxoplasma gondii and Listeria monocytogenes). The animals in the same breeding facility were also clinical examined, and the present study evaluated the prevalence of specific anti-E. cuniculi antibodies using serological testing, both in animals and in people working with animals, after two clinical cases. The rabbits showed no clinical symptoms of the disease. Blood samples were taken for E. cuniculi infection from 50 clinically healthy rabbits. Anti-E. cuniculi antibodies were found in two asymptomatic and two clinically affected animals belonging to the same rabbit colony. Finally, the present study found that the 7.7% (4/52) prevalence of CIA, test positive in rabbits. E. cuniculi spores were detected in the urine of one clinically affected rabbit, and one seropositive animal caretaker after staining with the modified trichrome stain. In conclusion, the presence of seropositive, but apparently healthy rabbits indicates the need for screening examinations to detect the anti-E. cuniculi antibody in rabbits, especially considering the potential zoonotic risk. Therefore, persons should avoid contact with the urine of infected or healthy animals, and always use good personal hygiene when handling animals.

Tee, K. Y., Kao, J. P., Chiu, H. Y., Chang, M. H., Wang, J. H., Tung, K. C., … & Wu, J. T. (2011). Serological survey for antibodies to Encephalitozoon cuniculi in rabbits in Taiwan. Veterinary parasitology, 183(1-2), 68-71.
Abstract: Encephalitozoon cuniculi (E. cuniculi) is a microsporidian parasite commonly found in rabbits that can infect humans, causing encephalitozoonosis. Our laboratory recently confirmed the first case of encephalitozoonosis in a rabbit in Taiwan; the prevalence of encephalitozoonosis is not well documented, even when many clinics suspect pet rabbits as being infected. This study surveys the seropositivity of E. cuniculi using carbon immunoassay (CIA) and enzyme-linked immunosorbent assay (ELISA). Serological examination of 171 rabbits using CIA and ELISA showed that 63.2% (108/171) and 67.8% (116/171) were seropositive against E. cuniculi, respectively. Thirteen of the 14 rabbits (92.9%) with neurological symptoms were seropositive. Except for gender, health status and location had a significant effect on E. cuniculi seropositivity (p<0.05). Adult rabbits aged older than 4 months exhibited significantly higher seropositivity for E. cuniculi than young rabbits (p<0.05). In conclusion, this study shows that E. cuniculi is present and widespread among healthy rabbits in Taiwan. Therefore, the fields of veterinary and human medicine in Taiwan should be aware of this zoonotic issue and the resulting public health concern of encephalitozoonosis.

Habenbacher, B., Klang, A., Fragner, K., Dinhopl, N., Künzel, F., & Weissenböck, H. (2012). Comparative evaluation of specific methods for labeling of Encephalitozoon cuniculi in paraffin wax–embedded tissue samples. Journal of veterinary diagnostic investigation, 24(2), 370-375.
Abstract: Detection of the microsporidian Encephalitozoon cuniculi in tissue samples is considered difficult. The aim of the current study was to determine whether immunohistochemistry (IHC) and in situ hybridization (ISH) represent reliable methods for the detection of E. cuniculi in postmortem tissue samples of rabbits. Paraffin-embedded tissue sections of brain and kidneys of 48 naturally infected pet rabbits, 10 negative controls, and the eyes of 3 further rabbits were used for all investigations. By IHC in 19 animals (37.3%), spores could be clearly detected and were all equally stained. By ISH using a digoxigenin-labeled oligonucleotide probe, only 6 animals (11.8%) proved undoubtedly positive. In these cases, many parasite-like objects revealed strong typical purple-black positive signals. However, several of the examined samples showed only partial staining of the pathogen or unclear results. Thus, in order to find an explanation for these inconsistent ISH results and to take a more detailed look at the different developmental stages of the organism, electron microscopy was applied. Empty spores, which had already discharged their polar filaments, prevailed in total number. Taken together, both techniques are rather insensitive, but under the condition that sufficient numbers of microsporidia are present, IHC can be recommended for specific identification of E. cuniculi in tissue samples. In contrast, ISH failed to detect some developmental stages of the organism, and, as such, ISH is therefore considered an inappropriate diagnostic method.

Pilny, A. A. (2012). Excellence in exotics: case report: Encephalitozoon cuniculi-associated phacoclastic uveitis in a dwarf rabbit. Compendium (Yardley, PA), 34(11), E5.
[No Abstract Available]

Fukui, D., Bando, G., Furuya, K., Yamaguchi, M., Nakaoka, Y., Kosuge, M., & Murata, K. (2012). Surveillance for an outbreak of Encephalitozoon cuniculi infection in rabbits housed at a zoo and biosecurity countermeasures. Journal of Veterinary Medical Science, 12-0231.
Abstract: An outbreak of encephalitozoonosis occurred in a rabbit colony at a zoo in Japan. Throughout the two years after the onset, all 42 rabbits were investigated clinically, pathologically and serologically for prevention and control of the disease. Eleven rabbits (11/42, 26.2%) showed clinical symptoms. Of 38 rabbits examined to detect specific antibodies against Encephalitozoon cuniculi, 71.1% (n=27) were found seropositive; 20 out of 30 clinically healthy rabbits (except for 8 clinical cases) were seropositive. The infection rate was 76.2% (32/42), including 5 pathologically diagnosed cases. The results of serological survey revealed that asymptomatic infection was widespread, even among clinically healthy rabbits. However, encephalitozoonosis was not found by pathological examination in any other species of animals kept in the same area within the zoo. Isolation and elimination of the rabbits with suspected infection based on the results of serological examination were carried out immediately; however, encephalitozoonosis continued to occur sporadically. Therefore, all the remaining rabbits were finally slaughtered. Then, the facility was closed, and all the equipment was disinfected. After a two-month interval, founder rabbits were introduced from encephalitozoonosis-free rabbitries for new colony formation. Since then, encephalitozoonosis has not been seen in any animals at the zoo. In this study, biosecurity countermeasures including staff education, epidemiological surveillance and application of an “all-out and all-in” system for rabbit colony establishment based on serological examination were successfully accomplished with regard to animal hygiene and public health for the eradication of E. cuniculi.

Leipig, M., Matiasek, K., Rinder, H., Janik, D., Emrich, D., Baiker, K., & Hermanns, W. (2013). Value of histopathology, immunohistochemistry, and real-time polymerase chain reaction in the confirmatory diagnosis of Encephalitozoon cuniculi infection in rabbits. Journal of veterinary diagnostic investigation, 25(1), 16-26.
Abstract: Morphological lesions in kidneys and brain are all too often considered diagnostic for confirmation of encephalitozoonosis in rabbits. The current study evaluated the diagnostic value of histology versus other etiological tests, including immunohistochemistry and real-time polymerase chain reaction (PCR) for Encephalitozoon cuniculi infection diagnosis. Samples of brain, heart, lungs, intestine, liver, and kidneys from 81 rabbits were examined for morphological lesions attributed to E. cuniculi infection as well as for the presence of spores and E. cuniculi antigen. Of these, 55 rabbits were tested for E. cuniculi DNA. Histological changes consistent with E. cuniculi infection were seen in 33 rabbits (41%, 33/81) representing 87% (33/38) of all rabbits with confirmed E. cuniculi infection. Brains of these rabbits displayed 6 different types of focal lesions corresponding to the stage of infection and specific tissue response. In 5 rabbits that were tested positive, histology was either inconclusive or inconspicuous. Etiological diagnosis was based on histological spore detection in 16% (6/38) of infected rabbits. Immunohistochemistry was more sensitive (42%, 16/38) than histological spore detection, and real-time PCR proved to be the most sensitive of all investigated methods (30/35, 86% of the examined rabbits with E. cuniculi infection). Encephalitozoon cuniculi infection rarely occurs without characteristic kidney and brain lesions. However, the spectrum of brain changes is wider than previously reported. Based on these findings, confirmation of pathogenic E. cuniculi infection should include standard histology of the predilection sites and a specific etiological assay, preferably real-time PCR.

Selman, M., Sak, B., Kváč, M., Farinelli, L., Weiss, L. M., & Corradi, N. (2013). Extremely reduced levels of heterozygosity in the vertebrate pathogen Encephalitozoon cuniculi. Eukaryotic cell, 12(4), 496-502.
Abstract: The genomes of microsporidia in the genus Encephalitozoon have been extensively studied for their minimalistic features, but they have seldom been used to investigate basic characteristics of the biology of these organisms, such as their ploidy or their mode of reproduction. In the present study, we aimed to tackle this issue by mapping Illumina sequence reads against the genomes of four strains of E. cuniculi. This approach, combined with more conventional molecular biology techniques, resulted in the identification of heterozygosity in all strains investigated, a typical signature of a diploid nuclear state. In sharp contrast with similar studies recently performed on a distant microsporidian lineage (Nematocida spp.), the level of heterozygosity that we identified across the E. cuniculi genomes was found to be extremely low. This reductive intraindividual genetic variation could result from the long-term propagation of these strains under laboratory conditions, but we propose that it could also reflect an intrinsic capacity of these vertebrate pathogens to self-reproduce.

Grisdale, C. J., Bowers, L. C., Didier, E. S., & Fast, N. M. (2013). Transcriptome analysis of the parasite Encephalitozoon cuniculi: an in-depth examination of pre-mRNA splicing in a reduced eukaryote. BMC genomics, 14(1), 207.
Abstract: The microsporidian Encephalitozoon cuniculi possesses one of the most reduced and compacted eukaryotic genomes. Reduction in this intracellular parasite has affected major cellular machinery, including the loss of over fifty core spliceosomal components compared to S. cerevisiae. To identify expression changes throughout the parasite’s life cycle and also to assess splicing in the context of this reduced system, we examined the transcriptome of E. cuniculi using Illumina RNA-seq. We observed that nearly all genes are expressed at three post-infection time-points examined. A large fraction of genes are differentially expressed between the first and second (37.7%) and first and third (43.8%) time-points, while only four genes are differentially expressed between the latter two. Levels of intron splicing are very low, with 81% of junctions spliced at levels below 50%. This is dramatically lower than splicing levels found in two other fungal species examined. We also describe the first case of alternative splicing in a microsporidian, an unexpected complexity given the reduction in spliceosomal components. Low levels of splicing observed are likely the result of an inefficient spliceosome; however, at least in one case, splicing appears to be playing a functional role. Although several RNA decay genes are encoded in E. cuniculi, the lack of a few key players could be reducing decay levels and therefore increasing the proportion of unspliced transcripts. Significant proportions of genes are differentially expressed in the first forty-eight hours but not after, indicative of genetic changes that precede the intracellular to infective stage transition.

Kimura, M., Aoki, M., ICHIKAWA, M., MATUSO, K., Yagita, K., & Itagaki, T. (2013). Detection and genotype of Encephalitozoon cuniculi DNA from urine and feces of pet rabbits in Japan. Journal of Veterinary Medical Science, 12-0567.
Abstract: A newly developed nested polymerase chain reaction (PCR) assay targeting the internal transcribed spacer (ITS) region of the ribosomal DNA was applied to detect and characterize Encephalitozoon cuniculi DNA from pet rabbits in Japan. The analysis was carried out using 257 urinary samples and 314 fecal samples collected from 307 pet rabbits in the age group of 1 month to 12 years from 30 different prefectures of Japan and 107 fecal samples and 3 urinary samples collected from 1-month-old rabbits from 3 breeding facilities in Japan. We detected 840-bp amplicons in 20 urinary samples (7.78%) from the pet rabbits of the 13 prefectures and in 1 urinary (33.3%) and 6 fecal (5.6%) samples from the rabbits of the 2 breeding facilities. The sequences (803 bp) of the 27 amplicons had no variations and completely coincided with the sequence of E. cuniculi genotype I. To the best of our knowledge, this is the first report on the detection and genotype characterization of E. cuniculi DNA from pet rabbits in Japan.

Res Vet Sci. 2013 Apr;94(2):295-8. doi: 10.1016/j.rvsc.2012.09.020. Epub 2012 Oct 22.
Lonardi, C., Grilli, G., Ferrazzi, V., Dal Cin, M., Rigolin, D., & Piccirillo, A. (2013). Serological survey of Encephalitozoon cuniculi infection in commercially reared rabbit does in Northern Italy. Research in veterinary science, 94(2), 295-298.
Abstract: The aim of the study was to carry out a serological survey of Encephalitozoon cuniculi in commercially reared rabbit does (Oryctolagus cuniculi) in Veneto region (Northern Italy). Two hundred and sixty blood samples from 13 farms were examined by a carbon immunoassay (CIA test) to detect the presence of antibodies anti-E. cuniculi. All sampled rabbit does were clinically healthy. Seropositivity against E. cuniculi was found in 196/260 (75.4%) sera and in all the sampled farms (100%). Logistic regression analysis showed that the size of the farm had no statistically significant effect on E. cuniculi positivity; whereas rabbits of the hybrid X showed a higher seropositivity (p<0.01) than rabbits belonging to other commercial breeds. Moreover, the age seemed to influence the seropositivity (p<0.05). This serological survey showed a high prevalence of E. cuniculi infection suggesting that this parasite may be endemic in industrial rabbitries in Northern Italy.

Ziętek, J., Dzięgiel, B., Kalinowski, M., Bartnicki, M., Kalinowska, A., & Winiarczyk, S. (2014). Diagnosis of the Encephalitozoon cuniculi infections in pet rabbits with neurological symptoms. Polish journal of veterinary sciences, 17(2), 361-363.
Abstract: The purpose of the study was the in vivo diagnosing of E. cuniculi invasions in pet rabbits with neurological symptoms using the Real-Time PCR, and determination of the rate of invasion, in this group of animals. The study involved 103 pet rabbits with neurological symptoms. Parasitic invasions were diagnosed using Real-Time PCR. The DNA of the parasites for molecular tests was isolated from the urine of the diseased animals. Out of the 103 tested DNA samples, the presence of the E. cuniculi genetic material was detected in 27 samples (26.21%). The melting temperature (Tm) of all products was 77.5 degrees C. The presence of parasitic DNA in the urine of 26.21% of examined animals indicates that E. cuniculi infections occur widely in pet rabbits in Poland and are a significant cause of neurological disorders in those animals.

Hein, J., Flock, U., Sauter-Louis, C., & Hartmann, K. (2014). Encephalitozoon cuniculi in rabbits in Germany: prevalence and sensitivity of antibody testing. Veterinary Record, vetrec-2013.
Abstract: The aim of this study was to investigate the prevalence of Encephalitozoon cuniculi antibodies in healthy and diseased rabbits in Germany. Age and gender dependencies were taken into consideration. The sensitivity of the E cuniculi antibody test and its relevance for the diagnosis of E cuniculi infection in rabbits was also examined. A total of 773 healthy and diseased rabbits were tested for E cuniculi antibodies (indirect immune fluorescence antibody test (IFAT) or carbon immunoassay (CIA). No differences between diseased and healthy rabbits were observed with regard to gender, but diseased rabbits were significantly older (P>0.001). Forty-three percent (336/773) of all rabbits were positive for E cuniculi antibodies. Of the diseased rabbits, 48 per cent (266/555) were positive for E cuniculi antibodies. While 96 per cent (91/95) of the rabbits with histopathologically or PCR confirmed encephalitozoonosis were E cuniculi antibody-positive, only 60 per cent (144/241) of the rabbits suspected of E cuniculi infection were antibody-positive. Of the healthy rabbits, 18 per cent (39/218) were positive for E cuniculi antibodies. Diseased rabbits were almost three times more likely to be E cuniculi antibody-positive than healthy ones (P>0.001; relative risk (RR): 2.68; 95% CI 1.99 to 3.61). The sensitivity of the E cuniculi antibody test was 96 per cent.

Varga, M. (2014). Questions around Encephalitozoon cuniculi in rabbits. Veterinary Record, 174(14), 347-348.
IT is estimated that one million rabbits are kept as pets in the UK (PDSA 2013). This makes them the third most popular pet after cats and dogs; however, until recently there has been minimal rabbit training available to veterinary undergraduates in the UK (the University of Edinburgh Royal [Dick] School of Veterinary Studies is a notable exception). Many more rabbits are being presented to veterinary surgeons for treatment, and rabbit owners (with access to online resources such as the Rabbit Welfare Association and RSPCA websites) are becoming more knowledgeable. There is an obvious mismatch in this situation, emphasising the need for the publication of clinically applicable, peer-reviewed rabbit research. Although the balance is now rapidly changing, many years with less informed veterinary input has led to misapprehensions being perpetuated about conditions and treatment of pet rabbits. There are notable exceptions to this, and the publication of the Textbook of Rabbit Medicine in 2002 (Harcourt-Brown 2002) made an enormous difference to many clinicians who were trying to treat rabbits to the same standard as cats and dogs. However, encephalitozoonosis remained one area where much confusion remained, and an area in which there were as many questions as answers.

Shin, J. C., Kim, D. G., Kim, S. H., Kim, S., & Song, K. H. (2014). Seroprevalence of Encephalitozoon cuniculi in pet rabbits in Korea. The Korean journal of parasitology, 52(3), 321.
Abstract: Encephalitozoon cuniculi is a microsporidian parasite commonly found in rabbits that can infect humans, causing encephalitozoonosis. The prevalence of encephalitozoonosis is not well documented, even when many clinics suspect pet rabbits as being highly infected. This study investigated the seropositivity of E. cuniculi using ELISA. The examination of 186 rabbits using ELISA showed that 22.6% (42/186) were seropositive against E. cuniculi. In analysis with healthy status, all 42 seropositive sera were collected from clinically normal rabbits. Moreover, the gender and age of pet rabbits did not have anysignificant effect on E. cuniculi infection. To the best of our knowledge, this is the first report to describe the seroprevalence of E. cuniculi in pet rabbits and suggests that pet rabbits could act as an important reservoir of encephalitozoonosis for both pet animals and humans in Korea.

Yaoqian, P. A. N., Shuai, W. A. N. G., Xingyou, L. I. U., Ruizhen, L. I., & Yuqian, S. U. N. (2015). Seroprevalence of Encephalitozoon cuniculi in Humans and Rabbits in China. Iranian journal of parasitology, 10(2), 290.
Abstract: Encephalitozoon cuniculi is a microsporidian parasite commonly found in rabbits that can infect humans, causing encephalitozoonosis. Our objective in this study was to evaluate the seroprevalence of this parasite in rabbits and humans in China. Overall, 300 serum samples each from clinically healthy rabbit and human were collected from three regions of China (Sichuan Province, Chongqing Municipality and Jilin Province) from January to September 2013 and tested for anti-E. Cuniculi antibodies using an ELISA. An overall seroprevalence of E. cuniculi was recorded as 56/300 (18.76%) and 29/300 (9.76%) in rabbit and human sera, respectively. The seropositivity of rabbit samples collected from Jilin province was 41%, which was significantly higher (P<0.01) than Sichuan Province (9%) and Chongqing Municipality (6%). Three breeds of rabbit were used in the present study and antibody detection in Rex Rabbit was significantly (P<0.01) higher than Japanese White and New Zealand Rabbit. In human, Jilin province was more prevalent (18%) followed by Sichuan Province (6%) and Chongqing Municipality (5%).The E. cuniculi was present and widespread among healthy rabbits and humans in China.

Zhang, X. X., Jiang, J., Cai, Y. N., Wang, C. F., Xu, P., Yang, G. L., & Zhao, Q. (2016). Molecular characterization of Enterocytozoon bieneusi in domestic rabbits (Oryctolagus cuniculus) in Northeastern China. The Korean journal of parasitology, 54(1), 81.
Abstract: A study of 426 rabbits from 3 cities in Jilin province (Changchun City and Jilin City) and Liaoning province (Shenyang City) was conducted between May and June 2015. The overall prevalence of E. bieneusi in rabbits was 0.94% (4/426), with 0% (0/116), 1.72% (3/174), and 0.74% (1/136) in Jilin, Changchun, and Shenyang City, respectively. Only 3 farms (farm 1 and farm 3 in Changchun City, farm 8 in Shenyang City) were PCR-positive for E. bieneusi. Moreover, rabbits of more than 6 months (1.72%) had the highest E. bieneusi prevalence, followed by rabbits of 4-6 months (1.26%), 2-3 months (0.58%), and less than 1 month (0%). Analysis of ITS gene of E. bieneusi suggested that all 4 E. bieneusi isolates were genotype D, and were classified as group 1a. The present results first demonstrated the existence of zoonotic E. bieneusi in domestic rabbits in China. Effective control measures should be implemented to prevent E. bieneusi infection in domestic rabbits, other animals, and humans.

Abu-Akkada, S. S., & Oda, S. S. (2016). Prevention and treatment of Encephalitozoon cuniculi infection in immunosuppressed rabbits with fenbendazole. Iranian journal of veterinary research, 17(2), 98.
Abstract: This study was conducted to evaluate the efficacy of oral administration of fenbendazole (20 mg/kg body weight) prior to and after experimental infection of immunosuppressed rabbits with Encephalitozoon cuniculi. A total of thirty rabbits were divided into five groups: NN (non-immunosuppressed; non-infected), IN (immunosuppressed; non-infected), IPI (immunosuppressed; protected-infected), ITI (immunosuppressed; treated-infected), and II (immunosuppressed; infected) groups. Fenbendazole was administered as a prophylactic for seven successive days before infection with E. cuniculi and as a treatment for four weeks initiated on the 28th day post-challenge (PC). Experimental rabbits were infected with intraperitoneal injection of 2 × 105E. cuniculi spores. Parameters evaluated were body weight, detection of spores in urine, serum antibody assay, hematological, biochemical and histopathological changes. The IPI and ITI groups showed a significant better final bwt than the II group. Spores were detected in urine of all infected rabbits from the 28th day PC until the end of the study. The IPI group showed the least values of antibodies (IgG) compared to the ITI and II groups. Concerning histopathological changes, the intensity of the lesions was marked particularly in the II rabbits and to a lesser extent in the ITI rabbits. Noticeable improvement was found in the IPI rabbits. It could be concluded that fenbendazole was effective to some extent in protection of rabbits against E. cuniculi infection, while when administered as a therapeutic no significant effects were observed.

Rodríguez-Tovar, L. E., Castillo-Velázquez, U., Arce-Mendoza, A. Y., Nevárez-Garza, A. M., Zarate-Ramos, J. J., Hernández-Vidal, G., … & Trejo-Chávez, A. (2016). Interferon γ and interleukin 10 responses in immunocompetent and immunosuppressed New Zealand White rabbits naturally infected with Encephalitozoon cuniculi. Developmental & Comparative Immunology, 62, 82-88.
Abstract: Levels of interferon (IFN)-? and interleukin (IL)-10 were measured in the serum of immunocompetent and immunosuppressed New Zealand White rabbits naturally infected with Encephalitozoon cuniculi. IFN-? levels were elevated in infected rabbits, and a synergic effect was observed in animals treated with the immunosuppressive agent dexamethasone (Dex). The role of IL-10 in infected rabbits remains unclear, as IL-10 levels were similar to those of negative controls. Dex appeared to exhibit a proinflammatory effect, as IFN-? levels were elevated in infected immunosuppressed rabbits. Similarly, Dex exhibited a synergic effect in infected immunosuppressed rabbits, as evidenced by the elevation in IFN-? production. These data indicate that the immune response to this glucocorticoid should be considered in the design of future animal model studies of immunosuppression.

Desoubeaux, G., del Carmen Piqueras, M., Pantin, A., Bhattacharya, S. K., Peschke, R., Joachim, A., & Cray, C. (2017). Application of mass spectrometry to elucidate the pathophysiology of Encephalitozoon cuniculi infection in rabbits. PloS one, 12(7), e0177961.
Abstract: Encephalitozoon cuniculi is a microsporidian species which can induce subclinical to serious disease in mammals including rabbits, a definitive natural host. The pathophysiology of infection has not been comprehensively elucidated. In this exploratory study, we utilized two mass spectrometry approaches: first, the analysis of the humoral response by profiling the microsporidian antigens as revealed by Western blot screening, and second, implementing the iTRAQ®-labeling protocol to focus on the changes within the host proteome during infection. Seven E. cuniculi proteins were identified at one-dimensional gel regions where specific seropositive reaction was observed by Western blot, including polar tube protein 3, polar tube protein 2, and for the first time reported: heat shock related 70kDa protein, polysaccharide deacetylase domain-containing protein, zinc finger protein, spore wall and anchoring disk complex protein EnP1, and translation elongation factor 1 alpha. In addition, there was a significant increase of nine host proteins in blood samples from E. cuniculi-diseased rabbits in comparison with non-diseased control subjects undergoing various inflammatory processes. This included serum paraoxonase, alpha-1-antiproteinase F precursor and alpha-1-antiproteinase S-1 which have presumptive catalytic activity likely related to infection control, and cystatin fetuin-B-type, an enzyme regulator that has been poorly studied to date. Notably, 11 proteins were found to be statistically increased in rabbits with neurological versus renal clinical presentation of E. cuniculi infection. Overall, this novel analysis based on mass spectrometry has provided new insights on the inflammatory and humoral responses during E. cuniculi infection in rabbits.

Künzel, F., & Fisher, P. G. (2018). Clinical signs, diagnosis, and treatment of Encephalitozoon cuniculi infection in rabbits. Veterinary Clinics: Exotic Animal Practice, 21(1), 69-82.
Abstract: Central vestibular dysfunction caused by Encephalitozoon cuniculi frequently mimics the condition of a peripheral disorder. A negative antibody titer rules out E cuniculi as the cause of present clinical signs. Cerebrospinal fluid analysis including polymerase chain reaction is considered an inappropriate diagnostic method for in vivo diagnosis of encephalitozoonosis. The usefulness of glucocorticoid anti-inflammatories in the treatment of encephalitozoonosis is called into question. Encouraging activity early in the course of disease and adding in therapeutic exercise may represent the most important part of therapy in rabbits with vestibular dysfunction associated with encephalitozoonosis.

Maestrini, G., Ricci, E., Cantile, C., Mannella, R., Mancianti, F., Paci, G., … & Perrucci, S. (2017). Encephalitozoon cuniculi in rabbits: Serological screening and histopathological findings. Comparative immunology, microbiology and infectious diseases, 50, 54-57.
Abstract: Serological prevalence of E. cuniculi infection was assessed in 183 rabbits from central Italy. In seropositive deceased rabbits, histopathological lesions were also evaluated. Sera from 118 rabbits from 6 intensive farms, 10 rabbits from 6 family farms, 16 rabbits from a zoo, 30 rabbits from 5 research laboratories and 9 pet rabbits from 9 different owners, were tested by an enzyme-linked immunosorbent assay. Data were statistically analysed. Tissue samples from brain and kidney of 10 deceased rabbits were formalin-fixed and subsequently analysed by histopathology and immunohistochemistry. Anti-E. cuniculi antibodies were found in 129/183 (70.5%) analysed sera. At statistical analysis, E. cuniculi seropositivity was significantly higher (p<0.05) in industrial and zoo rabbits. At histology, different degrees of pathological lesions were found in serological positive (9) deceased animals. In three rabbits deceased after showing neurological signs, the severity of the lesions was interpreted as a likely cause for their death.

Rodríguez-Tovar, L. E., Villarreal-Marroquín, A., Nevárez-Garza, A. M., Castillo-Velázquez, U., Rodríguez-Ramírez, H. G., Navarro-Soto, M. C., … & Trejo-Chávez, A. (2017). Histochemical study of Encephalitozoon cuniculi spores in the kidneys of naturally infected New Zealand rabbits. Journal of Veterinary Diagnostic Investigation, 29(3), 269-277.
Abstract: Encephalitozoon cuniculi is an important microsporidian pathogen that is considered an emergent, zoonotic, and opportunistic. It infects both domestic and laboratory rabbits, generating severe chronic interstitial and granulomatous nephritis with fibrosis and granulomatous encephalitis. Encephalitozoonosis is diagnosed in paraffin-embedded sections by examining the spores in the host tissues. The spores are difficult to observe when the samples are stained with hematoxylin and eosin (H&E), particularly when there is an inflammatory reaction and tissue damage. The spores are easily mistaken for other microorganisms, such as fungi (yeasts), protozoa, and bacteria. In our study, we used kidney samples from E. cuniculi-positive rabbits and employed 14 recommended histologic stains for detecting microsporidia spores: alcian blue, calcofluor white, Giemsa, Gram, Grocott, H&E, Luna, Luxol fast blue, Masson trichrome, modified trichrome stain (MTS), periodic acid-Schiff reaction (PAS), Van Gieson, Warthin-Starry (WS), and Ziehl-Neelsen (ZN).We concluded that MTS and Gram stain, detected by light microscopy, and calcofluor white stain, detected by ultraviolet light microscopy, are the best stains for detecting spores of E. cuniculi in paraffin-embedded tissues from infected rabbits. These stains were superior to WS, ZN, Giemsa, and PAS for identifying spores without background “noise” or monochromatic interference. Also, they allow individual spores to be discerned in paraffin-embedded tissues. MTS allows observation of the polar tube, polaroplast, and posterior vacuole, the most distinctive parts of the spore.

Sak, B., Jandová, A., Doležal, K., Kváč, M., Květoňová, D., Hlásková, L., … & Foitová, I. (2017). Effects of selected Indonesian plant extracts on E. cuniculi infection in vivo. Experimental parasitology, 181, 94-101.
Abstract: The present study was conducted to evaluate the methanolic extracts from several plant leaves widely used in traditional medicine to cure digestive tract disorders and in the self-medication of wild animals such as non-human primates, namely Archidendron fagifolium, Diospyros sumatrana, Shorea sumatrana, and Piper betle leaves, with regard to their antimicrosporidial activity against Encephalitozoon cuniculi in immunocompetent BALB/c mice determined using molecular detection of microsporidial DNA (qPCR) in various tissues and body fluids of infected, treated mice. Of the plant extracts tested, Diospyros sumatrana provided the most promising results, reducing spore shedding by 88% compared to untreated controls. Moreover, total burden per 1 g of tissue in the D. sumatrana extract-treated group reached 87% reduction compared to untreated controls, which was comparable to the effect of the standard drug, Albendazole. This data represents the baseline necessary for further research focused on determining the structure, activity and modes of action of the active compounds, mainly of D. sumatrana, enabling subsequent development of antimicrosporidial remedies.

Künzel, F., & Fisher, P. G. (2018). Clinical signs, diagnosis, and treatment of Encephalitozoon cuniculi infection in rabbits. Veterinary Clinics: Exotic Animal Practice, 21(1), 69-82.
Abstract: Central vestibular dysfunction caused by Encephalitozoon cuniculi frequently mimics the condition of a peripheral disorder. A negative antibody titer rules out E cuniculi as the cause of present clinical signs. Cerebrospinal fluid analysis including polymerase chain reaction is considered an inappropriate diagnostic method for in vivo diagnosis of encephalitozoonosis. The usefulness of glucocorticoid anti-inflammatories in the treatment of encephalitozoonosis is called into question. Encouraging activity early in the course of disease and adding in therapeutic exercise may represent the most important part of therapy in rabbits with vestibular dysfunction associated with encephalitozoonosis.

Nevárez-Garza, A. M., Castillo-Velázquez, U., Soto-Domínguez, A., Montes-de-Oca-Luna, R., Zamora-Ávila, D. E., Wong-González, A., & Rodríguez-Tovar, L. E. (2018). Quantitative analysis of TNF-α, IL-4, and IL-10 expression, nitric oxide response, and apoptosis in Encephalitozoon cuniculi–infected rabbits. Developmental & Comparative Immunology, 81, 235-243.
Abstract: The expression of tumor necrosis factor (TNF) -a, interleukin (IL) -4 and IL-10, as well as apoptosis and nitric oxide (NO) levels were measured in the brain and kidneys of immunocompetent and immunosuppressed New Zealand White rabbits infected with Encephalitozoon cuniculi. All of the animals had clinical signs histopathological lesions compatible with encephalitozoonosis and were E. cuniculi-positive by using a carbon immunoassay test. Encephalitozoon cuniculi infection promoted the expression of TNF-a and NO production in the kidneys of infected rabbits, and a synergic effect was observed in animal treated with dexamethasone. The IL-4 expression was similar in the brain and kidneys of infected rabbits, regardless of their immunologic status. The IL-10 mRNA expression in the brain of infected immunosuppressed rabbits was elevated when compared with positive controls. Apoptosis of granuloma mononuclear-like cells was detected in immunocompetent E. cuniculi-infected rabbits, but it was more evident in infected-immunosuppressed animals. Nitric oxide levels were elevated both in immunocompetent and immunosuppressed infected animals, but it was more apparent in the kidneys. These data suggest that modulation of the immune response by E. cuniculi could contribute to the survival of the parasite within phagocytic cells in granulomas via an as yet undetermined mechanism.

Wang, S., Yao, Z., Li, L., Pan, Y., Li, P., Nan, X., … & Zhang, Z. (2018). Seroprevalence of Toxoplasma gondii and Encephalitozoon cuniculi among domestic rabbits in central China. Parasite, 25.
Abstract: Rabbits (Oryctolagus cuniculus) are frequently reared for meat production in China. The aim of this study was to assess the seroprevalence of Toxoplasma gondii and Encephalitozoon cuniculi, and risk factors of infection in domestic rabbits raised in Henan province, central China. 1,213?serum samples of domestic rabbits were collected and tested for anti-T. gondii and anti-E. cuniculi antibodies using a modified agglutination test (MAT) and an enzyme-linked immunosorbent assay (ELISA), respectively. The serum positive rates of T. gondii and E. cuniculi were 128/1,213 (10.55%) and 235/1,213 (19.37%), respectively. Co-infection of T. gondii and E. cuniculi was demonstrated in 84?specimens; 44?rabbits were seropositive for T. gondii alone, while 151?rabbits were seropositive for E. cuniculi alone. The main risk factors simultaneously associated with T. gondii and E. cuniculi infection were the age of the rabbit, the type of food, and the rabbit rearing system. Serum positive rates of T. gondii and E. cuniculi among domestic rabbits were high, indicating the possibility of public health issues.

Gomes, F. E., de Matos, R., & Ledbetter, E. (2018). Phacoemulsification of bilateral cataracts in two pet rabbits. Open veterinary journal, 8(2), 125-130.
Abstract: Two 3 year-old, healthy, client-owned Lop rabbits presented with bilateral cataracts. After performing a physical examination, bloodwork, ocular ultrasonography and electroretinography, both animals were deemed good surgical candidates for phacoemulsification. Bilateral cataract surgery was performed and both rabbits regained vision in both eyes. Both animals developed post-operative ocular hypertension and one animal developed corneal ulcers immediately after surgery. Both surgical complications resolved with medical management. This case series describes phacoemulsification of bilateral cataracts in 2 companion rabbits and the use of an intraocular lens in 1 rabbit. Surgical treatment of cataracts can be considered as a treatment option whenever a healthy rabbit is visually impaired due to cataracts.

ÖZKAN, Ö., & Alcigir, M. E. (2018). Subacute stage of Encephalitozoon cuniculi infection in eye lesions of rabbit in Turkey. Iranian journal of parasitology, 13(2), 301.
Abstract: Encephalitozoon cuniculi is an opportunistic microsporidian parasite that can affect a number of different species of mammalian animals and humans. The parasite can pose also threat for rabbits even though it causes several sporadic and asymptomatic infections. Infection of eyes is common and clinical symptom of ocular infection may include uveitis and cataracts. We found out subacute findings in naturally infected animals and show here a first described eye lesions as well as central nervous system and kidneys in Turkey.
The rabbits (n:171) of breeding units were observed to daily clinical examination for infection of E. cuniculi during three years. The eyes of five rabbits (2.9%) showed white intraocular masses or cataracts in the breeding units during daily examinations. The infection was described clinicopathologically in collected organ samples in the animals. During observation, macroscopically, corneal lesions and opacity and impaired lens were taken into attention as well as hyperemia in central nervous system and kidney. Histopathologically, parasitophorous vacuoles pertaining to E. cuniculi were detected in all three tissues during different routine Haematoxylin-Eosin and Gram stainings. Degenerative and necrotic changes in epithelium of cornea and lens and also neurons and tubules were predominantly observed in addition to nonpurulent interstitiel nephritis and encephalitis. The results from study lead to subacute findings especially in eye during natural E. cuniculi infections following asymptomatic and latent changes among breeding colony. The lesions indicated sub-acute stage of E. cuniculi infection in eye lesions of rabbit in Turkey.

Kotkova, M., Sak, B., & Kváč, M. (2018). Differences in the intensity of infection caused by Encephalitozoon cuniculi genotype II and III-Comparison using quantitative real-time PCR. Experimental parasitology, 192, 93-97.
Abstract: Microsporidia are a group of obligate intracellular eukaryotic parasites, which are able to infect a wide range of animals, including humans. Four genotypes of Encephalitozoon cuniculi have been found to date. The different courses of microsporidiosis described in humans, which are dependent on immunological status of the host and genotype of E. cuniculi, have been successfully imitated in murine models. In the present study, we quantified the microsporidial burden in individual organs of a murine experimental model, using qPCR and we compared the parasitic load of two genotypes of E. cuniculi, namely genotype II and III (EC II and EC III). While the extent of microsporidiosis caused by EC II gradually increased over 35 days post infection (DPI) in both immunocompetent and immunodeficient mice and caused death in the latter at 28 DPI, EC III had spread into all host organs by seven DPI and was not lethal for either mouse strain during the experimental time period. Moreover, EC III persisted in many organs until termination of the experiment. The number of microsporidial spores in individual organs was ten times higher in EC III-infected animals compared to those infected with EC II. EC II infection also progressively shifted towards organs outside the gastrointestinal tract (GIT) in both monitored mouse strains; whereas, EC III infection equally remained in both the GIT and organs outside the GIT. With the increasing use of molecular methods in diagnostics, it is important to better understand the pathophysiology of microsporidia, including its ability to escape from the immune system and persist in host organisms. Our results indicate that pathogenicity is not directly connected to spore burden, as infection caused by E. cuniculi genotype II is less extensive and spreads more slowly within the host organism than infection caused by E. cuniculi genotype III, but which caused the earlier death of immunodeficient mice.

Ozkan, O., & Alcigir, M. E. (2018). Encephalitozoonosis infection in a traditional rabbit farm with neurological manifestations. Veterinary parasitology, 262, 26-29.
Abstract: Encephalitozoon cuniculi, a zoonotic and opportunistic pathogen, can cause latent infection, especially in lagomorphs. Nowadays, this member of the Eukaryotes has drawn significant attention in the fields of veterinary and public health. The purpose of this study was to determine the seroprevalence of infection in a New Zealand rabbit farm that has a clinical history of neurological manifestations including head tilt ataxia, aggressiveness, seizures, and circling and rotational movements around the body length axis, but the general conditions and food intake were normal. Blood samples were taken from 42 breeding rabbits and researched for E. cuniculi antibodies. Out of that, 25 (59%) animals resulted positive against the pathogen. The rabbit was found to be seropositive for E. cuniculi antibodies, but negative for Toxoplasma gondii and Listeria monocytogenes antibodies. Hematological and serum biochemical parameters were measured at reference intervals. No brain tissue impairment was observed the computed tomography (CT) scan. As a result of these histopathological findings, the brain cortex presented severe neuronal degeneration and partial myelin loss, with reactive diffuse gliosis against the parasite spores was observed to the histopathology. These results are possibly related to the early stage of infection because the parasitic infestation comprise long time spreading. E. cuniculi DNA was detected on brain tissues using polymerase chain reaction (PCR), and it partial DNA sequence was identified as E. cuniculi genotype I.

This post was last updated March 4, 2019