Coccidiosis is a major protozoan disease of young rabbits caused by members of the genus Eimeria. Earlier reports on Eimeria spp. infecting rabbits in India are of Gill and Ray (1960). In commercially reared rabbits the infection mostly occurs as a subclinical disease causing growth retardation and alteration of feed conversion (Peeters et al., 1981). The present communication reports the effect of age, sex, breed, season and management on the prevalence of coccidiosis and the different species of Eimeria in domestic rabbits in and around Thrissur.

Data on the prevalence of coccidiosis in rabbits were collected by random screening of faecal samples of rabbits of the Rabbit Research Station, Mannuthy and those of different rabbit farms in and around Thrissur District and also from rabbits brought for post-mortem at the Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy during the period from October 2001 to September 2002. The faecal samples were examined by standard laboratory techniques viz., sedimentation to identify the coccidial species. A portion of the screened faecal suspensions were made to sporulate in shallow layers of 2 per cent potassium dichromate solution in petridishes for subsequent differentiation of various species (Catchpole and Norton, 1979). The oocyst sporulation time and the morphological characters of both unsporulated and sporulated oocysts (Pellerdy, 1965) were taken as criteria for identification of species of Eimeria. Micrometry was carried out to measure the size of oocysts and a minimum of 30 to 50 oocysts of each type was studied and the average was determined (Catchpole and Norton, 1979).

During present study, 550 faecal samples were examined out of which 102 animals were found to harbour coccidial infection indicating a prevalence of 18.54 per cent. Coccidiosis was found to occur more in young rabbits below three months of age (76.47 per cent) which might be due to a lower resistance and also due to the fact that the adult female rabbits usually act as carriers in the farm and transmit the infection to young ones (Table 1). This is in accordance with the studies of Mykytowycz (1962), Rajkhowa (1996) and Suchitrasena et al. (1998). In the present study, more number of female rabbits harboured the infection (63.72 per cent) than the males (36.27 per cent) which might be attributed to lesser number of male animals that were available for screening. Breed-wise prevalence studies revealed highest infection in New Zealand White (10.9 per cent) followed by Grey Giant (3.63 per cent) which concurred with the observations made by Sanyal and Srivastava (1986). The prevalence of infection was highest in August 2002 (81.81 per cent) indicating that favourable humidity and temperature levels hastened sporulation and it corraborates with the result of Rajkhowa (1996), who reported rise of infection in areas of high humidity and rainfall. The cold wet South-West monsoon season recorded higher occurrence (46.07 per cent) of coccidiosis in rabbits denoting the significance of rainfall and dampness for the sporulation of oocysts (Table 1). This was in accordance with the observations of Meitei et al. (1988)., Rajkhowa (1996) and Gurpartap and Khahra (1997). In the present study, rabbits maintained in commercial farms where coccidiostats were regularly given were free from the disease. Whereas non-medicated domestic rabbits housed in humid and damp atmosphere developed coccidial infection instantly which corraborated well with the observations of Peeters et al. (1981).

Six species of intestinal coccidia were observed and identified as Eimeria magna, E. media, E. perforans, E coedcola, E. flavescens and E. piriformis. No oocysts of E. stiedai were encountered throughout the survey. Majority of the positive cases had mixed infection. Eimeria magna (86%), E. media (80%) and E. perforans (86%) occurred most frequently. E. coedcola (50%) and E. flavescens (15%) were common and E. piriformis (8%) was relatively rare.

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