First molecular surveillance and estimation of risk factors of anaplasma marginale infection among indigenous, crossbred and exotic cattle

Abstract

Anaplasmosis is an important disease of cattle, worldwide including Pakistan. Blood samples (n=384) were collected from asymptomatic dairy cattle located in all tehsils of district Jhang belonging to either age, sex and breed. Samples were analyzed for the detection of A. marginale infection using blood smear microscopy and PCR targeting msp1β gene. Epidemiological information related to host, area, season and management was collected on a questionnaire. Overall prevalence of anaplasmosis based on blood smear and PCR was 29.43% (113/384) and 37.24% (143/384); respectively. Univariate analysis, indicated age breed, tick infestation, herd size, feeding pattern, interval between acaricidal application and season as significant risk factors (p≤0.20). Nevertheless, multivariate analysis revealed age of >2-4 years (OR 1.95), exotic cattle (OR 2.23), herd size >50 (OR 2.09), tick infestation (OR 2.56), 30 days interval between acaricidal application (OR 3.21) and summer season (OR 2.56) were significantly at higher risk (p<0.05) associated with molecular occurrence of A. marginale infection in cattle. Based on the results of first molecular surveillance, it can be concluded that bovine anaplasmosis is endemic in the area and tick infested exotic young cattle kept in larger herds in summer season are at higher risk associated with A. marginale as compared to indigenous and crossbred animals. Further studies are required at large scale to investigate genetic diversity for better prevention and control of bovine anaplasmosis in the region.