The occurrence of Cryptosporidium parvum and C. muris in wild rodents and insectivores in Spain.

Five rodent and two insectivore species were investigated for Cryptosporidium at seven sites in north-eastern Spain. Of the 442 animals studied, 82 Apodemus sylvaticus, 1 A. flavicollis, 5 Mus spretus, 1 Rattus rattus, 8 Clethrionomys glareolus and 13 Crocidura russula were infected with only C. parvum. Eleven A. sylvaticus and 2 C. glareolus were infected with only C. muris and 16 A. sylvaticus, 1 M. spretus and 2 C. glareolus showed mixed infections. Both cryptosporidial species were found in most study areas. No causal relationship was found between intrinsic host factors (age and sex) and the parasitic prevalence in the most captured host species (A. sylvaticus and C. russula). Extrinsic factors such as collection site of host, seasonality and covering vegetation exerted different influence on the prevalence of Cryptosporidium. Small mammals could become one of the most important sources of cryptosporidial oocysts in those areas where neither farm animals nor significant human activity are present. This is the first study to report the infection of M. spretus and C. russula by C. parvum and the first finding of C. muris in M. spretus.