Rabbit encephalitozoonosis in Kenya - SAGE Journals

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May 5, 2018 - Summary. Encephalitozoon cuniculi infection was diagnosed in a laboratory rabbit breeding colony at. Muguga, Kenya. This is the first report of.
Laboratory Animals (1992) 26, 219-221

Rabbit encephalitozoonosis

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in Kenya

H. O. WESONGA & M. MUNDA Kenya Agricultural Research Institute, National Veterinary Research Centre, Muguga, PO Box 32, Kikuyu, Kenya

Summary 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. Keywords: Encephalitozoon; Laboratory rabbit; Kenya Encephalitozoon cuniculi is an intracellular microsporidian parasite which has a wide range of hosts, including rodents and rabbits, carnivores and primates (Shadduck & Pakes, 1971; Canning & Lorn, 1986; Hollister & Canning, 1987). A severe infection has been reported in broiler rabbits (Pattison et aI., 1971) and a mild infection in laboratory rabbits (Koller, 1969). Clinical signs of the disease in rabbits include paralysis and head tilt. Lesions found include small granulomas in the brain and chronic interstitial nephritis (Koller, 1969). The importance of encelphalitozoonosis to research workers is its possible interference with experimental results (Shadduck & Pakes, 1971). The disease is of importance in the rabbit meat industry because of its negative influence on the growth rate of rabbits (Pattison et al., 1971). It is also of significance to laboratory animal managers because of its possible role as a zoonosis (Hollister & Canning, 1987).

Received 5 May /988; resubmitted October /99/; accepted /6 March /992

There are no reports on the occurrence of this disease in Kenya. The purpose of this survey was therefore to record its occurrence in the country. Materials and methods Seventeen New Zealand white (Muguga-bred) rabbits received from a large rabbit breeding colony for post-mortem examination were killed by cervical dislocation. Of these, 6 showed clinical signs of posterior paralysis, 4 were weak and recumbent while 7 were normal. Postmortem examination was carried out on 65 others that died due to illness of varying severity. In the breeding colony the rabbits were fed on rabbit pellets, hay and kale. Breeders were housed individually while weaners were housed in groups of approximately 25, on a solid concrete floor. Small pieces of brain, kidney, lung, liver and

small intestine were fixed in 10070 buffered formalin, wax embedded, cut at 5 JL thickness and stained with haematoxylin and eosin (H&E) for histological examination. Samples of small intestine and kidney were inoculated onto blood agar for bacteriological examination. Faecal samples were examined for coccidia as described in the MAFF handbook. Results Kidneys from 22 of 82 rabbits (27070)showed gross pathological changes. The 22 rabbits included 10 of the 17 rabbits received while alive (the 6 with posterior paralysis and the 4 that were weak) and 12 of the 65 received dead. The gross pathological changes were characterized by irregularly shaped, greyish-white spots and depressions on the surface. Histopathological changes included interstitial nephritis characterized by mononuclear cell infiltration and proliferation

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Wesonga & Munda

Fig. 1. Cerebrum showing Encephalitozoon parasite without cellular reaction x 1000 (H&E).

Fig. 2. Cerebrum showing granuloma formation associated with Encephalitozoon infection x 100 (H&E).

Rabbit encephalitozoonosis in Kenya of fibrous tissue. Spores of the parasite were observed in Gram stained kidney sections from two rabbits. The cerebellum and cerebrum of two rabbits carried foci of E. cuniculi, sometimes without (Fig. 1) and sometimes with mononuclear cell reaction consisting of glial cells and lymphocytes, forming a granuloma (Fig. 2). Perivascular cuffing and meningitis were observed. Coccidiosis and mucoid enteritis were diagnosed in 45 out of 82 rabbits (55070). Eimeria perforans and Eimeria irresidua were identified. Escherichia coli was isolated from the small intestine. Pneumonia was diagnosed in 19 out of the 82 rabbits. Five of the rabbits with coccidiosis and 2 with pneumonia showed renal lesions. Discussion

Encephalitozoon cuniculi infection in rabbits has been described fully by various authors. The observations made in this study are similar to the descriptions by Koller (1969).

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In their investigation, Owen and Gannon (1980) observed that the most common route of transmission of E. cuniculi is the oral one. In the survey reported here, both E. cuniculi and coccidia infections were observed to be associated with poor hygiene conditions on solid floor pens. In the absence of wire bottomed cages which are recommended to keep down both infections, simple hygiene methods (including regular and frequent cleaning of the pens with disinfectant) were recommended. It is expected that serological work will be carried out to determine the distribution of E. cuniculi infection in Kenya.

Acknowledgment The authors are grateful to J Ngaho, M Wairimu and L Too for technical assistance. This paper is published with the permission of the Director, National Veterinary Research Centre, Muguga, Kari, Kenya.

References Canning EU & Lorn J (1986) The Microsporidia of Vertebrates, pp 289. New York & London: Academic Press Hollister WS & Canning EU (1987) An enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to Encephalitozoon cuniculi and its use in determination of infections in man. Parasitology 94, 209-219 Koller LD (1969) Spontaneous Nosema cuniculi infection in laboratory rabbits. Journal of the American Veterinary Medical Association 155, 1108-1114

Owen DG & Cannon J (1980) Investigation into the transplacental transmission of Encephalitozoon cuniculi in rabbits. Laboratory Animals 14, 35-38 Pattison M, Clegg FG & Duncan AL (1971) An outbreak of Encephalomyelitis in broiler rabbits caused by Nosema cuniculi. Veterinary Record 88, 404-405 Shadduck JA & Pakes SP (1971) Encephalitozoonosis (Nosematosis) and Toxoplasmosis. American Journal of Pathology 64, 657-674