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Title: Species of Cryptosporidium Detected in Weaned Beef Calves on Cow-Calf Operations in the United States

Author
item Fayer, Ronald
item Santin-Duran, Monica
item DARGATZ, DAVID - US Department Of Agriculture (USDA)

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2010
Publication Date: 3/3/2010
Citation: Fayer, R., Santin, M., Dargatz, D. 2010. Species of Cryptosporidium Detected in Weaned Beef Calves on Cow-Calf Operations in the United States. Veterinary Parasitology. 170(3-4):187-192.

Interpretive Summary: Cattle have been reported to be infected with 4 species of Cryptosporidium, each species presenting a different prevalence pattern relative to the age of the cattle. For example, Cryptosporidium parvum, the zoonotic species, has been found in a high numbers of young monogastric calves but in relatively few calves after weaning when they convert to rumenal nutrition. The number of cattle found infected with C. bovis and C. ryanae increases immediately after weaning and then decreases steadily as cattle approach maturity. The number of cattle found infected with C. andersoni has been extremely low in pre-weaned calves and reaches its highest levels in yearling heifers and mature cows. These age-related patterns of Cryptosporidium species have been well documented in dairy cattle but few studies have been conducted with beef cattle and most reports have been based on microscopic identification of oocysts in fecal specimens. Recently, C. bovis and C. ryanae were discovered as species distinct from C. parvum based on gene sequencing. Consequently, reports of C. parvum in beef cattle that were based solely on microscopic identification of oocysts were unable to distinguish C. bovis and C. ryanae from C. parvum now require re-evaluation. The present study is the most in-depth study of Cryptosporidium in beef calves in the US using molecular methods to identify the species. Cryptosporidium was detected in 20.5%.of 819 calves 6-18 months of age from 20 states. Of most significance, the zoonotic species, C. parvum, was not detected in any samples from these calves, a finding that parallels reports for dairy cattle of similar age in which less than 1% were found to harbor this species.

Technical Abstract: To determine the species and distribution of Cryptosporidium in weaned beef calves in the United States, fecal specimens were collected from 819 calves between 6 and 18 months of age from 49 operations in 20 states (Alabama, California, Colorado, Georgia, Idaho, Iowa, Kansas, Louisiana, Mississippi, Missouri, Nebraska, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Tennessee, Texas, Virginia, and Wyoming). Fresh feces, collected either from the ground or directly from the rectum of each animal, were sieved and subjected to density gradient centrifugation to remove fecal debris and to concentrate oocysts. DNA extracted from each specimen was subjected to the polymerase chain reaction (PCR) using primers for the SSU rRNA gene. All PCR positive specimens were subjected to sequence analysis. Cryptosporidium was detected in 20.5% of the fecal samples. Cryptosporidium ryanae, C. bovis and C. andersoni were detected in 1.8, 4.8, and 14.0% of the 819 samples, respectively. California (number operations [n] = 2), Iowa (n=3), and Nebraska (n=7) had the highest prevalence of infected calves with 44.4, 41.0 and 40.2% infected, respectively. Cryptosporidium was not detected in any calves from Alabama (number operations [n] =1), Georgia (n=2), New Mexico (n=1), South Dakota (n=1), Tennessee (n=1), or Texas (n=1). The zoonotic species, C. parvum, was not detected in any samples from weaned beef calves, a finding that parallels reports for dairy cattle of similar age in which less than 1% were found to harbor this species