The prevalence of Cryptosporidium and Giardia spp. in fecal samples from free-ranging white-tailed deer (Odocoileus virginianus) in the southeastern United States.

The prevalence of Cryptosporidium sp. and Giardia sp. in fecal samples collected from free-ranging white-tailed deer (Odocoileus virginianus) was determined for animals in Virginia and Mississippi. The 34 Virginia samples came from young of the year (< or =6 months of age) presented to the Wildlife Center of Virginia, and the 360 Mississippi samples came from animals (> or =6 months of age) collected from 42 different sites across the state. Cryptosporidial oocysts were detected in 8.8% and 5.0% and Giardia sp. cysts were detected in 2.9% and 1.1% of the samples from Virginia and Mississippi, respectively. Analysis of data by collection site was not possible because of the small number of samples from some sites. Therefore, collection sites in Mississippi were grouped by the stream basin in which they occurred. Binary logistic regression analysis indicated the probability of infection with Cryptosporidium sp. decreased with increasing age of animal in all positive stream basins except 1, in which the pattern was reversed. This is the first report of either Cryptosporidium sp. or Giardia sp. in free-ranging white-tailed deer. The role of white-tailed deer in the epidemiology of these parasites is unknown. However, this study demonstrates that white-tailed deer shed cysts and oocysts of both parasites in the environment and must be considered potential sources of contamination.