Molecular and serological prevalence of Anaplasma marginale in water buffaloes in northern Brazil.

Bovine anaplasmosis, caused by Anaplasma marginale, occurs in tropical and subtropical regions throughout the world and is a major constraint on cattle production in many countries. Approximately 60% of the buffalo herds in South America are located in northern Brazil. However, compared with the research on cattle, research on buffaloes has been neglected. Therefore, the present study was conducted to investigate the distribution of A. marginale in water buffaloes in northern Brazil. A total of 500 buffalo blood samples was randomly collected from 16 provinces and was analyzed using both nPCR assay and ELISA techniques. The percentage of animals that were seropositive for A. marginale according to ELISA was 49% (245/500). The main risk factors associated with seroprevalence were the region (p=0.021; OR=1.2) and the reproductive status (p=0.0001; OR=1.6). Anaplasma marginale DNA was detected in 5.4% (27/500) of the sampled buffaloes. Our data provide information about the incidence of A. marginale infection in water buffaloes and may guide future programs aimed at controlling the disease in the northern region of Brazil. Although these water buffaloes are exposed to A. marginale, a low rate of A. marginale PCR-positive animals was found, which could be explained by the habitat in which the sampled animals live because they exhibited a low rate of attached ticks on their skin.