Prevalence of Theileria annulata in dairy cattle in Mashhad area, Iran

A total of 160 dairy cattle from 78 farms were clinically examined and investigated for the presence of Theileria spp., Anaplasma spp. in blood smears in Mashhad area, in Iran from 2002 to 2003. The prevalence of Theileria annulata and Anaplasma marginale infection was 32 (20%) and 15 (9.38%), respectively. Mixed infections occurred in 9 (5.62%) dairy cattle. The parasitaemia of Theileria annulata infection was higher than Anaplasma marginale infection and clinical signs were observed in 23 (14.37%) dairy cattle that were infected with Theileria annulata. In the present study, the highest prevalence of Theileria annulata infection in dairy cattle was observed in less than 1 year old animals (40%) and seasonally in summer (45%). In addition, the prevalence of Anaplasma marginale infection in relation to age and season was not statistically significant.