Serological survey for antibodies to Encephalitozoon cuniculi in rabbits in Taiwan

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.     

Seroprevalence of antibodies to Encephalitozoon cuniculi and Toxoplasma gondii in farmed domestic rabbits in Egypt

Rabbit sera from ten commercial farms representing three provinces in Northern Egypt (Behera, Alexandria and Khafr El-Sheikh) were submitted to serological screening for Encephalitozoon cuniculi using an enzyme-linked immunosorbent assay and for Toxoplasma gondii using an indirect hemagglutination test. Antibodies against E. cuniculi were detected in 36/240 (15%) sera examined while antibodies against T. gondii showed a seroprevalence of 22/194 (11.34%). Both infections were detected in all of the examined farms. These results are of epidemiological relevance and public health importance because of the recognized susceptibility of humans to E. cuniculi and T. gondii infections; therefore, routine screening examinations of farm rabbits are advised considering the zoonotic potential of these parasites.     

Encephalitozoonosis in New Zealand rabbits and potential transmission risk

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.     

Seroprevalence of antibodies to Encephalitozoon cuniculi in domestic rabbits in Nigeria

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.     

Microsporidia (Encephalitozoon cuniculi) in wild rabbits in Australia

Objective To determine the prevalence of infection with Encephalitozoon cuniculi i n wild rabbit populations in Western Australia, and to isolate the organism from seropositive rabbits.
Design Serological screening of wild and clinically affected domestic rabbit populations.
Sample population Eighty-one wild rabbits from southwestern Western Australia and 29 laboratory rabbits.
Procedure Indirect immunofluorescence antibody technique and in-vitro amplification of parasite isolates in fibroblast cultures.
Results 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.
Conclusion 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.     

Serological survey of Encephalitozoon cuniculi in farm rabbits in Italy

Rabbit sera (n = 1600) from 40 commercial farms were submitted to a serological screening for Encephalitozoon cuniculi by an enzyme-linked immunosorbent assay (ELISA) and a carbon immunoassay (CIA test). Antibodies anti-Encephalitozoon cuniculi were found in 505/1600 (31.6%) sera analysed, and all the farms (100%) resulted positive. Rabbits older than 4 months showed a significantly higher seropositivity for E. cuniculi (chi-squared test: p < 0.0001) than rabbits under 4 months, E. cuniculi sero-prevalence showed an increasing trend in rabbits within the farm along with the increase in the “number of rabbits on the farm”; however, this trend was not significant (Spearman’s correlation: p = 0.073).The findings of the present study confirm that rabbit is the main reservoir of E. cuniculi; they are of epidemiological relevance and immediate public health importance because of the recognized infectivity in humans by the microsporidium.     

Hepatic lesions in rabbits infected with Encephalitozoon cuniculi administered per rectum.

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.     

Efficacy and safety of topical administration of selamectin for treatment of ear mite infestation in rabbits

OBJECTIVE: To evaluate the efficacy and safety of topical administration of selamectin in rabbits naturally infested with Psoroptes cuniculi. DESIGN: Randomized controlled trial. ANIMALS: 48 mixed-breed domestic rabbits with active P. cuniculi mite populations and clinical ear lesions. PROCEDURES: Rabbits were randomly allocated to 1 of 6 treatment groups. On day 0, rabbits in groups 1 and 2 were given vehicle, rabbits in groups 3 and 4 were given selamectin at a dose of 6 mg/kg (2.7 mg/lb), and rabbits in groups 5 and 6 were given selamectin at a dose of 18 mg/kg (8.2 mg/lb). On day 28, rabbits in groups 2, 4, and 6 were given a second dose of vehicle or selamectin. Otoscopic examinations were performed and ear lesion size was measured weekly for 8 weeks. Quantitative viable mite counts were performed on day 56. RESULTS: On days 7 through 56, lesion sizes for all selamectin-treated groups were significantly lower than sizes for control groups; there were no significant differences in lesion sizes among selamectin-treated groups. All rabbits in the 2 control groups had viable adult P. cuniculi mites for the duration of the study, as determined by otoscopic examination, whereas all rabbits in the 4 selamectin-treated groups were free from P. cuniculi mites on days 7 through 56. No adverse reactions associated with selamectin treatment were observed. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that topical application of selamectin at a dose of 6 or 18 mg/kg can completely eliminate mites from rabbits naturally infested with P. cuniculi.     

Encephalitozoonosis in household pet Nederland Dwarf rabbits (Oryctolagus cuniculus)

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.     

兔脑炎原虫病患兔血清中IgG的测定

以临床症状和病理学变化确诊为兔脑炎原虫感染的家兔为研究对象 ,经间接 EL ISA法对其机体体液免疫状况进行研究 ,并与健康家兔进行比较 ,结果表明兔脑炎原虫病兔外周血 Ig G含量明显高于对照组 (P<0 .0 5)。提示兔脑炎原虫入侵兔体后 ,病兔体液免疫功能有所增强。     

Immunohistochemical identification of Encephalitozoon cuniculi in phacoclastic uveitis in four rabbits

PURPOSE: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.     

The curative and antioxidative efficiency of doramectin and doramectin+vitamin AD3E treatment on Psoroptes cuniculi infestation in rabbits

In the present study, the efficiency of the administration of doramectin (DOR) and DOR+vitamin AD3E (VIT), and the influence of these agents on oxidative stress parameters in rabbits infested by Psoroptes cuniculi (P. cuniculi) were investigated. DOR (200 microg/kg) and DOR (200 microg/kg)+VIT AD3E were administered to infested rabbits intramuscularly (IM). The administration of DOR and DOR+VIT improved the healing of ear lesions on day seven. Increase in the plasma malondialdehyde (MDA) level and erythrocyte catalase (CAT) activity, and decrease in glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities were determined in infested rabbits. In the rabbits which were administered DOR+VIT, plasma MDA levels decreased, and erythrocyte GSH-Px and SOD activities increased on day seven. In conclusion, DOR and DOR+VIT combination were effective against P. cunuculi infestation. Infestation stimulated oxidative stress. VIT treatment resulted in antioxidant activity against oxidative stress induced by P. cuniculi infestation.     

Use of selamectin for the treatment of psoroptic and sarcoptic mite infestation in rabbits

Selamectin, a novel avermectin compound, was evaluated for its efficacy against naturally occurring infestations of Psoroptes cuniculi and Sarcoptes scabiei. A total of 42 New Zealand rabbits with psoroptic mange and 37 Angora rabbits with sarcoptic mange were used in the present study. On day 0, infested rabbits were treated topically with either selamectin at minimum dose of 6 mg kg(-1) (6-18 mg kg(-1) for New Zealand rabbits, n = 31 and 10-12 mg kg(-1) for Angora rabbits, n = 23) or vehicle only (control groups, n = 11 for New Zealand rabbits, n = 14 for Angora rabbits). The efficacy of selamectin was assessed both clinically and parasitologically by the presence or absence of viable mites. Rabbits were scraped for sarcoptic mites on days 7, 14, 28, 42 and 56 and had otoscopeic and/or microscopic examination for the detection of Psoroptes mites on days 7, 14, 42 and 56. Fisher's exact test was used to assess differences between the vehicle and selamectin treatment in the number of rabbits without mites (cure rates) on each assessment date. It was found that significantly fewer selamectin-treated rabbits had mites detected on skin scrapings (for S. scabiei) or otoscopeic and/or microscopic examination (for P. cuniculi) (P < 0.01) than the vehicle group. Results of the present study suggest that selamectin is effective against naturally infestations of P. cuniculi and S. scabiei in rabbits.     

Prevalence of IgG antibodies to Encephalitozoon cuniculi and Toxoplasma gondii in cats with and without chronic kidney disease from Virginia

Kidney disease is a common and serious condition in domestic cats. There are numerous causes of kidney disease including parasitic infection. Encephalitozoon cuniculi is a microsporidian parasite that develops in the kidneys of rabbits and causes chronic renal disease. Little has been reported concerning E. cuniculi in cats and no serological studies on this parasite in cats have been conducted in the United States to date. The present study explored the possibility that E. cuniculi is an unrecognized contributor to the high prevalence of kidney disease observed in cats. A serological survey was conducted to determine the prevalence of IgG antibodies to spores of E. cuniculi in cats with and without a diagnosis of chronic kidney disease (CKD) according to the International Renal Interest Society (IRIS) staging system. Likewise, samples were examined for IgG antibodies to Toxoplasma gondii, a common well studied protozoan of cats. Plasma and sera were obtained from 232 feline patients at the Virginia-Maryland Regional College of Veterinary Medicine teaching hospital. With the investigators blinded to the renal status of test subjects, samples were screened via indirect immunofluorescent antibody assay (IFA). Thirty-six of the 232 cats met the IRIS staging system criteria for CKD. Antibodies to E. cuniculi were found in 15 of the 232 samples, which included 4 of the 36 cats with CKD. Sera from cats serologically positive to E. cuniculi did not react to spores of E. intestinalis or E. hellem when examined in the IFA. Antibodies to T. gondii were found in 63 of the 232 samples, which included 10 of the 36 cats with CKD. The prevalence of antibodies in cats with CKD to either protozoan was not significantly different (P>0.05) from the cats without CKD in the study. Collectively the results do not support the hypothesis that either E. cuniculi or T. gondii play a significant etiologic role in the occurrence or progression of CKD in cats.     

Efficacy of an injectable formulation of eprinomectin against Psoroptes cuniculi, the ear mange mite in rabbits

Thirty rabbits naturally infected with ear mange mite, Psoroptes cuniculi, were subcutaneously administrated with a single dose of eprinomectin at 100, 200 and 300 microg/kg body weight or vehicle on day 0. The extent of lesions was scored on day -6 (prior to treatment), day 0 (treated), days 7, 14, 21, 28 and 35, the ear scabs were collected simultaneously; mites in scabs were examined and counted. The results showed that a single dose of eprinomectin at 200 or 300 microg/kg body weight following subcutaneous administration was able to eliminate P. cuniculi infection in rabbits, and a dose of eprinomectin at 100 microg/kg could significantly reduce mites but was unable to eliminate P. cuniculi.     

Clinical symptoms and diagnosis of encephalitozoonosis in pet rabbits

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.     

Acaricidal activity of extract from Eupatorium adenophorum against the Psoroptes cuniculi and Sarcoptes scabiei in vitro

The possible acaricidal activity of Eupatorium adenophorum was analyzed using extracts created by water decocting, ethanol thermal circumfluence, and steam distillation. The toxic effect of each extract was tested against Psoroptes cuniculi and Sarcoptes scabiei in vitro. Ethanol thermal circumfluence extract had strong toxicity against mites, killing all S. scabiei at 0.5 and 1.0 g/ml (w/v) concentration, while 1g/ml extract was also found to kill all P. cuniculi within a 4-h period. Similarly, 0.25, 0.5 and 1.0 g/ml concentration of extract had strong toxicity against S. scabiei, with median lethal time (LT(50)) values at 0.866, 0.785 and 0.517 h, respectively. 0.5 g/ml and 1g/ml showed strong acaricidal action against P. cuniculi; the LT(50) values were 0.93 h and 1.29 h, respectively. The median lethal concentration (LC(50)) values were 0.22 g/ml for Scabies mite and 0.64 g/ml for P. cuniculi in 1h. The results indicated that E. adenophorum contains potent acaricidal ingredients; as a first step in the potential development of novel drugs, it may provide new acaricidal compounds for the effective control of animal acariasis.     

Comparative efficacy of injection routes and doses of ivermectin against Psoroptes in rabbits

Rabbits infested with Psoroptes ovis (Hering) or with P cuniculi (Delafond) were injected IM or subcutaneously with ivermectin or with vehicle. A single injection of ivermectin (200 micrograms/kg) either IM or subcutaneously was inadequate to eliminate all mites in the ears of the rabbits. However, a single injection of ivermectin at 400 micrograms/kg, regardless of the route of injection, eliminated all P cuniculi mites, but eliminated P ovis mites in only 50% of the rabbits. Ivermectin was more effective against P cuniculi than against P ovis at both doses tested, regardless of the route of injection.     

Encephalitozoon cuniculi in pet rabbits

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.     

IL-2在自然感染兔脑炎原虫獭兔体内免疫作用的研究

为观察 IL-2在自然感染兔脑炎原虫獭兔体内的免疫作用 ,用双抗体夹心 EL ISA试剂盒对 8只自然感染兔脑炎原虫的獭兔和 4只健康长耳白对照兔的血清及培养 3 d和 4d的脾和淋巴结的细胞培养上清中的 IL-2进行了检测。检测结果为病兔与对照兔 IL -2平均含量差异不显著 (P >0 .0 5) ,但病兔 IL -2平均含量高于对照兔。提示 IL -2对病兔产生了一定的免疫作用 ,但可能不扮演主要角色