Asymptomatic cryptosporidiosis in Zambian dairy farm workers and their household members.

The prevalence of Cryptosporidium and the possibility of zoonotic transmission on dairy farms were examined. Eighteen cases of cryptosporidiosis (prevalence 6%) were identified in 82 farm workers and 207 household members. Furthermore, 70 (34%) of 207 calf samples were positive. Based on the 70kDa heat shock protein and the 18S rDNA gene, Cryptosporidium parvum was identified in 75% of the positive farm workers and in 60% of the household members. Of the positive calves, 62% were infected with C. parvum, indicating a possible zoonotic transmission on these farms.