Infection Patterns of Cryptosporidium spp. in Dairy Calves of Western Wisconsin

Abstract

Cryptosporidium is a genus of protozoan parasites that live on the surface of epithelial cells in the digestive tract. They infect a wide range of vertebrates, including humans. Bovine cryptosporidiosis, primarily caused by infection with Cryptosporidium parvum, has long been associated with neonatal calf scours. When a major human outbreak occurred in Milwaukee in 1994, surface water contamination by agricultural runoff was identified as the source of infection. While Cryptosporidium has been reported worldwide, there have been no reports documenting the prevalence of this parasite in Wisconsin cattle. Sampling 11 different dairy farms, we analyzed fecal specimens from a total of 99 pre-weaned calves. We found that 42 of the calves were infected with the parasite, and calves 8-14 days of age were most likely to be infected. We suggest that contaminated soil and maternity pens are reservoirs for calf infections. Our results may indicate the widespread nature of cryptosporidiosis in Wisconsin dairy cattle. Consequently, veterinarians should consider Cryptosporidium when assessing herds that experience chronic calf scours.