Prevalence of Babesia Divergens and Anaplasma Phagocytophilum Infection in Clinically Normal Dairy Cattle in South-West England

Tick-borne diseases pose an ongoing risk to cattle health and productivity across Europe, yet the prevalence and importance of infection in clinically normal cattle remain poorly understood. This study investigated the prevalence of Babesia divergens and Anaplasma phagocytophilum in dairy cattle in SouthWest England, a region endemic for bovine babesiosis and tick-borne fever. Blood samples (n = 806; 741 adult cows and 65 heifers) were collected from apparently healthy cattle on 13 farms during September-October 2024 and tested using multiplex real-time PCR. Adult cows were sampled on 12 farms and heifers sampled on two farms only. A. phagocytophilum was detected on 11 farms, with within-herd prevalence in adult cattle ranging from 4% to 39% and up to 56% in heifers. Overall cattle-level prevalence was 13.6% (95% CI: 11.4-16.2%), comprising 52.3% in heifers and 10.3% in adult cattle. B. divergens was detected on two farms, with an overall cattle-level prevalence of 0.6% (95% CI: 0.2-1.4%); detection occurred in both adult cattle (0.3%) and heifers (4.6%). One heifer was coinfected with both pathogens. Detection of A. phagocytophilum was significantly more frequent than B. divergens (McNemar's χ² = 95.7, p < 0.0001). These findings demonstrate PCR detectable infection with both pathogens in cattle without observable clinical signs at the time of sampling. Such infections may contribute to pathogen persistence in endemic regions, with implications for cattle health and productivity that warrant further research.