Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/2009
Publication Date: 4/15/2009
Citation: Santin, M., Trout, J.M., Fayer, R. 2009. A Longitudinal Study of Cryptosporidium, Giardia, and Enterocytozoon Bieneusi Infections in Naturally Infected Dairy Cattle from Birth to Two Years of Age. BARC Poster Day. Interpretive Summary:
Technical Abstract: Fecal specimens were collected from 30 calves from birth to 24 months of age at a dairy farm in Maryland to determine the prevalence and age distribution of Cryptosporidium, Giardia, Enterocytozoon bieneusi species/genotypes. It is crucial to know which species and/or genotypes are actually present to determine their public health implications. After centrifugation to remove fecal debris and concentrate any parasites that might be present, specimens were examined by polymerase chain reaction (PCR). A fragment of the SSU-rDNA gene of Giardia and Cryptosporidium and fragment of the internal transcriber spacer (ITS) region of the rDNA gene of E. bieneusi were amplified by PCR and all positive PCR products were sequenced. All 30 calves shed Cryptosporidium, Giardia, and E. bieneusi at some time during the study. For Cryptosporidium, the highest prevalence was observed at 2 weeks of age when 29 of the 30 calves were excreting oocysts. Prevalence was higher in pre-weaned calves (less than 8 wk of age) (45.8% of all samples were positive) than in post-weaned calves (3-12 mo of age) (18.5%) and heifers (12-24 mo of age) (2.2%). Sequence data for 190 Cryptosporidium PCR-positive specimens identified 4 species: Cryptosporidium parvum, C. bovis, C. ryanae and C. andersoni, with a cumulative prevalence of 100, 80, 60, and 3.3%, respectively. The zoonotic species, C. parvum, constituted 97% of infections in pre-weaned calves but only 4% and 0% of infections in post-weaned calves and heifers, respectively. For Giardia, the highest prevalence of infection was at 4 and 5 weeks of age with 25 of 30 calves excreting cysts. Pre-weaned calves had the highest prevalence (60.8%), followed by post-weaned calves (32.1%) and heifers (11.4%). Sequence analysis of the 312 Giardia PCR-positive specimens revealed the presence of Assemblages A (zoonotic) and E (livestock), with a cumulative prevalence of 70 and 100%, respectively. Assemblage A was not detected in pre-weaned calves, but was detected in 6.9% and 4.7% of post-weaned calves and heifers, respectively. For E. bieneusi, the highest prevalence was observed at 4 months of age when 28 of the 30 calves were excreting spores. Post-weaned calves exhibited the highest prevalence (44.4%), followed by pre-weaned calves (11.7%) and heifers (10.6%). Sequence data for 239 E. bieneusi PCR-positive specimens identified genotypes J, I and BEB4 that appear to be cattle-specific. Genotype I was detected in all calves while genotypes BEB4 and J were detected briefly mostly in heifers. These findings indicate that calves are infected with 2 zoonotic pathogens, C. parvum and G. duodenalis Assemblage A, and could be a significant reservoir leading to human infectious.