NATURAL CRYPTOSPORIDIUM INFECTION IN RABB ITS AFTER WEANING

The first occurrence of Cryptosporidium parvum Tyzzer, 1912 in broiler rabbits in the Czech Republic is reported. The protozoon was determin ed on the basis of morphometrical parameters of oocysts and of localiz ation of endogenous developmental stages. The dynamics of natural Cryp tosporidium infection was studied in a group of 72 young rabbits after weaning (their age ranging from 23-33 to 82-92 days) obtained from si x large flocks and used in a feeding experiment. C. parvum was found i n rabbits from four farms (Tab. I). Animals under observation were div ided into 9 subgroups according to the genotype (Hyla 2000, California White, crosses of New Zealand x California, New Zealand White, Cunist ar and Zika) as well as according to the farm of origin. The animals w ere housed in 28 cages under the conditions of two-floor cage technolo gy. The upper floor consisted of cages housing three head, the lower f loor two head each. The animals were fed ad libitum with commercial fe ed mixture (till the average age of 64 days supplemented with Robenidi n as coccidiostat). During the first 10 days of observation pooled sam ples of droppings from each cage were examinated by flotation-centrifu gation method according to Breza (1957) and Pavlasek (1991) in the int ervals of three to four days, later one-week intervals. Post mortem sc rapings from mucous epithelium taken from young rabbits were examinate d (to reveal endogenous developmental stages of C. parvum) together wi th digesta (to detect oocysts of the protozoon) taken from the full le ngth of the small intestine using method of native preparations and Gi emsa stain. In one 37-day dead animal the small and large intestines w ere examined histologically. The maximum number of youg rabbits infect ed with C. parvum were 30-40 and 33-43 days old (Fig. 1). In animals o f this age category the oocysts of the protozoon were found in pooled samples in 11 and 12 cages (39.3 and 42.9%) from totally 28 cages unde r study. In rabbits of more than 50 days of age the occurrence of infe ction was significantly decreased (3.7%). During the experiment seven rabbits (9.7%) died; six of them (8.3%) at the age of 30-40 days. All these naturally infected and dead animals represented cases of monoinf ection with C. parvum. The major clinical signs were typical diarrhoea lasting 3-5 days, inappetency, apathia, lethargy, prominent signs of exhaustion followed by dehydration of the organism. Atrophy of villi o f the ileum in one of young rabbits was found histologically. Table II presents concrete data on significantly lower body weights (the decre ase being 7-61.5%) as compared with rabbits of the same age not infect ed with cryptosporidia, It was not possible to evaluate objectively th e differences in susceptibility to C. parvum infection between the ind ividual genotypes of rabbits. As was found in the course of our furthe r studies (unpublished data) a possible source of infection of young r abbits can be represented by their mothers in which oocysts are excret ed sporadically shortly before parturition and during several days aft er it. Cryptosporidium infection (cryptosporidiosis) in flocks of broi ler rabbits is taken as a new protozoal disease in the Czech Republic and C. parvum as one of possible agents in cases of disorders of diges tive tract, namely in rabbits after weaning.