INFECTIVITY OF CRYPTOSPORIDIUM-MURIS ISOLATED FROM CATTLE

The infectivity of a bovine isolate of Cryptosporidium muris for vario us animals was studied by transmission experiments. Neonatal BALB/c mi ce, adult BALB/c mice, SCID mice, common voles (Microtus arvalis), ban k voles (Clethrionomys glareolus), common field mice (Apodemus sylvati cus), Mongolian gerbils (Meriones unguiculatus), desert gerbils (Gerbi lus gerbilus), guinea pigs, rats, rabbits and goats were used to test the infectivity of this isolate. Among these host species, only Mongol ian gerbils were susceptible to the infection and discharged C. muris oocysts in their faeces. The prepatent period for 8-week-old Mongolian gerbils was 15-19 days, the patent period varied between 18 and 36 da ys. More protracted chronic infections have been observed in gerbils i mmunosuppressed with methylprednisolone. No signs of clinical illness or macroscopic changes were seen in infected gerbils. Cryptosporidial developmental stages were detected in the stomach, histopathological c hanges were characterized by epithelial hyperplasia and mucosal hypert rophy without inflammatory exudate. In spite of the fact that C. muris was able to infect gerbils, we do not consider gerbils to be a true h osts for C. muris of cattle origin. Based on our results, we suggest t hat significant differences in host specificity of individual C. muris isolates exist, and that wild rodents are not reservoir for C. muris infection of cattle. (C) 1998 Elsevier Science B.V.