| prevalence of cryptosporidium species and genotypes in mature dairy cattle on farms in eastern united states compared with younger cattle from the same locations. | 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 ssurrna gene. pcr-positive products were purified and sequenced. pcr-positive findings were obtained from cows in all seven state ... | 2007 | 17287086 |