1. Infection Patterns of Cryptosporidium spp. in Dairy Calves of Western Wisconsin Department of Biology University of Wisconsin–Eau Claire Matt Brewer and Dr. Darwin Wittrock Acknowledgements We would like to thank the participating farms for their cooperation. We also thank the Osseo Veterinary Service, Mondovi Veterinary Clinic, and Chippewa Veterinary Clinic. This project was supported by University of Wisconsin Eau Claire Office of Research and Sponsored Programs differential tuition grants funding. Objectives  Determine if cryptosporidiosis is common in pre-weaned dairy calves of Wisconsin  Identify factors which may influence the occurrence of Cryptosporidium within this age group Results Forty-two calves (42.4%) were shedding Cryptosporidium oocysts. At least one calf was shedding oocysts at each farm. Age-related variation of infection rates was observed. Infection rates were highest in calves ages 8-14 days old (p=.05, Figure 3). Differences in infection rates were associated with different housing methods (Figure 4). Calves living in individual pens were more likely to be infected with Cryptosporidium than calves housed in community pens (p<.002). When housed in plastic “hutches,” calves were more likely to be infected than calves in other pen types (p<.05). The use of straw or corn stalk bedding significantly decreased infection rates (p=.05 ). Future Research Light microscopy is not a reliable tool for identifying Cryptosporidium on a species level. Although C. parvum is the primary species infecting young calves, C. andersoni has been frequently observed in adult cows. C. bovis, C. suis, and several isolates without species status have also been reported in cattle. Our future work will utilize molecular methods to identify the prevalence of different species in dairy cattle of western Wisconsin References Feltus, D.C., et al.. 2006. Evidence supporting zoonotic transmission of Cryptosporidium spp. in Wisconsin. Journal of Clinical Microbiology. 44: 4303-4308. Hlavsa, M.C., J.C. Watson, and M.J. Beach. 2005. Cryptosporidiosis surveillance- United States. Morbitity and Mortality Weekly Report. 54: 1-8. Kuczynska, E., D.R. Shelton, Y. Pachepsky. 2005. Effect of bovine manure on Cryptosporidium parvum attachment to soil. Applied and Environmental Microbiology. 71: 6394-6397. Santin, M., et al.. 2004. Prevalence and age-related variation of Cryptosporidium species and genotypes in dairy calves. Veterinary Parasitology. 122: 103-117 Introduction Cryptosporidium is a genus of widely distributed protozoan parasites that infect the epithelium of the gastrointestinal tract. They infect a wide range of vertebrates including humans. The infective stage, called the oocyst, is particularly resilient and has been found to survive several months in soil and water. Frequent human outbreaks have been observed in the Midwestern United States, with the highest incidence being reported in Wisconsin each year from 1999 to 2002. Researchers have recently found genetic evidence linking human cryptosporidiosis in Wisconsin to Cryptosporidium parvum (Feltus et al., 2006). From: Hlsava et al., 2005 Bovine cryptosporidiosis, primarily caused by infection with C. parvum, has long been associated with neonatal calf diarrhea and has caused considerable economic losses Despite the fact that Wisconsin has a high incidence of human cryptosporidiosis associated with species of bovine origin, there have been no studies assessing the prevalence of the parasite in Wisconsin dairy cattle. Discussion This study involved a variety of dairy farms in a geographical area spanning five counties. The farms varied greatly with respect to herd size and husbandry practices. We believe that these farms represent average dairy operations in Wisconsin. Therefore, our results indicate that neonatal bovine cryptosporidiosis is common in the region. Our observation of age related infection is consistent with the results of authors reporting C. parvum (Santin et al., 2004). Although at least three species of Cryptosporidium may infect cattle, C. parvum is likely the primary species infecting pre-weaned calves in western Wisconsin. The observation that cryptosporidiosis is more prevalent in individually housed calves is intriguing. This, in addition to the fact that most infected calves shed oocysts at approximately one week of age, may indicate a natural cow-calf cycle. However, most of the study farms reported that calves are removed from their mother immediately after calving. Further examination of the data reveals that the high prevalence value observed in individually housed calves is representative of calves living in hutches. It was our observation that calves housed in hutches often had little bedding outside of the hutch. Coincidentally, lower infection rates were observed in calves with generous amounts of straw or corn husk bedding. The high occurrence of Cryptosporidium in pens with little bedding may reflect the adhesive properties of oocysts. Researchers have recently found that manure enhances oocyst attachment to soil (Kuczynska et al., 2005). Consequently, bare ground previously occupied by a hutch is a reservoir for calfhood infection. Figure 2. Location of study farms in the Chippewa Valley Eau Claire Chippewa Clark Pepin Dunn Buffalo Trempealeau Jackson Figure 4. Differences in infection with Cryptosporidium attributed to calf housing P value Pearson  2.04.002 3719 Straw/Corn Husk 2023Soil 5228All Other Pens 514Hutch 4238Individual Pen 415 Community Pen Cryptosporidium Pen Type Bedding Type Proximity to other calves 4.40.05 9.41 3.81 No. Positive No. Negative Figure 3. Age related variation of dairy calves shedding Cryptosporidium spp. oocysts. Calves 8-14 days old were most likely to be shedding oocysts (p<.05). Methods Three fecal smears were prepared from each sample. Smears were heat fixed with a bunsen burner and stained with carbol-fuchsin dye. Each smear was examined by light microscopy under oil immersion (1000x) for three minutes. Oocysts appeared as 5 μm pink-red spheres. When at least 2 typical oocysts were found on any slide, the calf from which the sample was drawn was considered to be infected. Fecal specimens were collected from a total of 99 pre-weaned Holstein calves living on 11 farms in Chippewa, Eau Claire, Jackson, Pepin, and Trempealeau Counties (Figure 2). Fecal samples were obtained rectally, using a different glove for each calf. They were then sealed in a plastic jar and immediately transported to UW-Eau Claire for examination. Birth date, sex, breed, and housing data were collected for each calf