Submitted to: Veterinary Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/7/2006
Publication Date: 3/1/2007
Citation: Fayer, R., Santin, M., Trout, J.M. 2007. Prevalence of Cryptosporidium species and genotypes in mature dairy cattle on farms in Eastern United States. Veterinary Parasitology. 145:260-266. Interpretive Summary: Cryptosporidium is genus of protozoan parasites that contains over 15 species, many infecting humans as well as domestic and wild animals. Because the sources of human infection are not always known and because cattle appear to be a potential source it is imperative to understand the species present in cattle and their prevalence. Feces collected from 541 milking cows on two dairy farms each in Vermont, New York, Pennsylvania, Maryland, Virginia, North Carolina, and Florida were examined for the presence of Cryptosporidium oocysts. Molecular methods were used to detect and identify the species present. The major species capable of infecting both humans and dairy cattle is Cryptosporidium parvum. It is highly prevalent in pre-weaned calves but in the present study of mature milking cows it was found in only 0.4% of the 541 animals examined, suggesting that mature dairy cattle are a relatively low risk source of infection for humans.
Technical Abstract: Feces collected from 541 milking cows on two dairy farms each in Vermont, New York, Pennsylvania, Maryland, Virginia, North Carolina, and Florida were examined for the presence of Cryptosporidium oocysts. Oocysts were concentrated from 15 g of feces from each cow and DNA was extracted. A two-step nested PCR protocol was used to amplify an 830 base pair fragment of the SSU rRNA gene. PCR-positive products were purified and sequenced. PCR-positive findings were obtained from cows in all 7 states and from 11 of 14 farms. Cryptosporidium parvum, C. bovis, and C. andersoni were found on 2, 6, and 8 farms, and infected 0.4, 1.7, and 3.7% of the 541 cows, respectively. The overall lower prevalence of Cryptosporidium in these cows was very highly significant (p< 0.0001) compared with younger cattle and the relative prevalence of each species of Cryptosporidium also differed when compared with younger cattle previously examined on most of these same farms. The very low level of infection with C. parvum, the major species pathogenic to both cattle and humans, suggests that mature dairy cattle are a relatively low risk source of infection for humans.