Prevalence of Cryptosporidium among dairy cows in Thailand.

Cryptosporidium species are frequently associated with diarrhea among AIDS patients in Thailand, and dairy herds are a possible source of some of these infections. A cross-sectional study was performed to determine if Cryptosporidium is present among dairy cows in Thailand. Fecal samples were randomly collected from 363 Holstein-Friesian dairy cows from 108 of 860 farms in the Nong Pho region of central Thailand. The average prevalence of Cryptosporidium among dairy cows was 9.4%, according to an assay for Cryptosporidium-specific antigen (CSA) and 0.6% by microscopic examination of acid-fast stained feces. CSA was detected in all host age categories tested, but was most prevalent among calves (15.1%). Overall, 31.5% of farms were contaminated with Cryptosporidium infections. Fifty percent of poorly managed farms had CSA-positive cows, which were more likely to contaminate water and raw milk, while 12.9% of farms with acceptable management practices had CSA-positive cows. There was no association between the detection of Cryptosporidium and other gastrointestinal parasites. These results indicate that Cryptosporidium is enzootic among Thai dairy cattle, and suggest that cattle could have a role in zoonotic cryptosporidiosis in Thailand.