Sporadic cryptosporidiosis in a rural population is asymptomatic and associated with contact to cattle.

Fecal samples each followed by a completed questionnaire were obtained from 233 persons representing 80 households. Using the formalinether concentration method combined with the acid-fast staining oocysts of Cryptosporidium were found in 7 (3 %) persons. 63 persons had contact to cattle, and asymptomatic cryptosporidiosis was diagnosed in 6 of them. Cryptosporidiosis was not found in any of the 51 persons with contact to some other animal but not cattle, and none of the 7 Cryptosporidium positive persons had been traveling abroad. We also obtained fecal samples from 15 calves from 7 households. Six of the calves (40 %) harbored Cryptosporidia and manifest enteritis was detected in those under age of 1 month. Five out of 14 farms had problems of neonatal calf diarrhea. Human cryptosporidiosis was more frequent on such problem farms. The results indicate that in rural population, human cryptosporidiosis is mainly asymptomatic and occurs mainly in residents of cattle-rearing farms.