|Graczyk, T - JOHNS HOPKINS UNIV|
|Lewis, E - NOAA, OXFORD MD|
Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 8, 2000
Publication Date: November 1, 2000
Interpretive Summary: Eimeria species, Cryptosporidium parvum and Giardia duodenalis infect livestock. The infectious stages of each are spread by fecal-oral transmission. The latter two species also infect humans causing clinical illness and sometimes mortality and both have become recognized as a prevalent and widespread contaminants of surface waters throughout North America. Cattle are often blamed as a major source of Cryptosporidium. Until now there has been little evidence that postweaned and adult cattle in North America are infected with either parasite. Data in the present study clearly document the presence of low level asymptomatic infections with both parasites in dairy and beef cattle in Maryland, indicating that older cattle can serve as sources of infectious organisms.
Technical Abstract: The prevalence of Cryptosporidium, Giardia, and Eimeria, in healthy, asymptomatic, post weaned and mature cattle was investigated on three Maryland farms. One farm, a dairy research facility, had 150 multiparous Holstein milking cows; 24 were examined and Cryptosporidium andersoni was detected in three (12.5%) but neither Giardia nor Eimeria was detected. The esecond farm, a commercial dairy, had 57 multiparous Holstein milking cows and an equal number of heifers. Of 19 cows examined, C. parvum, Giardia duodenalis, and Eimeria bovis and/or E. ellipsoidalis was detected in two (10.5%), two (10.5%) and one (5.26%) cow, respectively. Of 23 heifers examined, C. parvum, Giardia, and Eimeria bovis and E. ellipsoidalis, was detected in two (8.7%), four (17.4%), and five (21.7%), heifers, respectively. The third farm, a beef cattle breeding and genetics research facility, had 180 7- to 9-month old purebred black Angus. Of 118 examined for C. parvum and Giardia 34 (28.8%) and 44 (37.3%) were positive, respectively; of 97 examined for E. bovis and/or E. ellipsoidalis 32 (33.0% were positive). These findings, based on a method with a minimum detection level of 100 oocysts of C. parvum/g of feces, which underestimates the number of infected cattle, clearly demonstrate the presence of low level, asymptomatic infections in post weaned and adult cattle in the United States and indicate the potential role of such cattle as reservoirs of infectious parasites.