Cryptosporidium parvum infection involving novel genotypes in wildlife from lower New York State

Cryptosporidium, an enteric parasite of humans and a wide range of other mammals, presents numerous challenges to the supply of safe drinking water. We performed a wildlife survey, focusing on white-tailed deer and small mammals, to assess whether they may serve as environmental sources of Cryptosporidium. A PCR-based approach that permitted genetic characterization via sequence analysis was applied to wildlife fecal samples (n = 111) collected from September 1996 to July 1998 from three areas in lower New York State. Southern analysis revealed 22 fecal samples containing Cryptosporidium small-subunit (SSU) ribosomal DNA; these included 10 of 91 white-tailed deer (Odocoileus virginianus) samples, 3 of 5 chipmunk (Tamias striatus) samples, 1 of 2 white-footed mouse (Peromyscus leucopus) samples, 1 of 2 striped skunk (Mephitis mephitis) samples, 1 of 5 racoon (Procyon lotor) samples, and 6 of 6 muskrat (Ondatra zibethicus) samples. All of the 15 SSU PCR products sequenced were characterized as Cryptosporidium parvum; two were identical to genotype 2 (bovine), whereas the remainder belonged to two novel SSU sequence groups, designated genotypes 3 and 4. Genotype 3 comprised four deer-derived sequences, whereas genotype 4 included nine sequences from deer, mouse, chipmunk, and muskrat samples. PCR analysis was performed on the SSU-positive fecal samples for three other Cryptosporidium loci (dihydrofolate reductase, polythreonine-rich protein, and beta-tubulin), and 8 of 10 cloned PCR products were consistent with C. parvum genotype 2. These data provide evidence that there is sylvatic transmission of C. parvum involving deer and other small mammals. This study affirmed the importance of wildlife as potential sources of Cryptosporidium in the catchments of public water supplies.