Prevalence of Theileria sergenti infection in Korean native cattle by polymerase chain reaction

Abstract

This study was performed to investigate the prevalence of theileriosis and to compare the prevalence ofthis disease in Korean native cattle reared under different environmental conditions, namely, in a grazing area and anon-grazing area by polymerase chain reaction. Three hundred and one Korean native cattle (276 cows and 25 bulls)that had not received prior treatment or been vaccinated to prevent theileriosis were examined by PCR for Theileriasergenti infection from 2001 to 2002. In our study, the parasitemia range in T. sergenti-positive cattle by microscopywere from 0.1 to 3% (mean 0.8%). In terms of mean prevalence, 204 of the 301 Korean native cattle (67.8%) werepositive reaction by PCR. Our results also revealed that the infection rate among cows (70.3%) was significantlyhigher than that among bulls (40.0%) (p < 0.01). T. sergentiinfection among the over 3 year-old-group (75%) had asignificant higher prevalence than that among the less than 3 year-old-group (61.8%) (p < 0.05). Our data alsoshowed that grazing areas (76.1%) had the significant higher prevalence than non-grazing areas (51%) (p < 0.001).In conclusion, this study demonstrates that the prevalence of T. sergentiinfection is high and that its prevalence ingrazing cattle is higher than that in non-grazing cattle. Therefore, life-long treatment and the development of anoptimal vaccine are needed to reduce the numbers of bovine theileriosis in both grazing and non-grazing areas.