|Santin, Monica - ARS VISITING SCIENTIST|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 25, 2004
Publication Date: June 2, 2004
Citation: Fayer, R., Santin, M., Trout, J.M. 2004. Prevalence of Crytosporidium in cattle in the United States. [Meeting Abstract]. Society of Protozologist. June 2004. Technical Abstract: 'Fifteen dairy farms in 7 states on the East Coast of the United States were each visited on 2 consecutive years to determinate the prevalence of Cryptosporidium species in pre-weaned (5 days to 2 months) and post-weaned calves (3 to 11 months), respectively. After each of 971 fecal specimens collected directly from each calf was sieved and subjected to density gradient centrifugation to remove debris and concentrate oocysts, specimens were examined by immunofluorescence microscopy, and polymerase chain reaction (PCR). For all PCR positive specimens the 18S rRNA gene of Cryptosporidium was sequenced. Cryptosporidium was identified from all farms. Types of housing appeared to have no influence with regard to prevalence of infection. Of 971 calves, 345 were infected with Cryptosporidium (35.5%), but more pre-weaned calves (253 of 503; 50.3 %) than post-weaned calves (92 of 468; 19.7%) were found to be infected. A total of 278 PCR-positive specimens characterized by gene sequencing revealed Cryptosporidium parvum, Cryptosporidium andersoni, and two unnamed Cryptosporidium genotypes- Bovine B and deer-like genotype. The prevalence of these Cryptosporidium species and genotypes appeared to be age related between pre- and post-weaned calves. Cryptosporidium parvum, the only zoonotic species/genotype, constituted 85% of the Cryptosporidium infections in pre-weaned calves but only 1% of the Cryptosporidium infections in post-weaned calves. These findings clearly demonstrate that earlier reports on the presence and prevalence of C. parvum in post-weaned cattle that were based solely on oocyst morphology must be reassessed using molecular methods to validate species and genotype. This finding also indicates that persons handling or otherwise exposed to calves under 2 months of age are at greater risk of zoonotic infection from Cryptosporidium than the risk of infection from exposure to older calves.