Molecular prevalence of Anaplasma spp. in cattle and assessment of associated risk factors in Northeast Thailand.

Abstract

Anaplasma spp. are common rickettsia species described in ruminant hosts, including cattle. The clinical signs of anaplasmosis range from asymptomatic to mortality. However, there are insufficient studies on epidemiology surveys of this blood pathogen. This study aimed to estimate the prevalence and risk factors of anaplasmosis in beef and dairy cattle in Northeast, Thailand. A total of 187 blood samples of beef and dairy cattle were collected from five provinces in Northeast Thailand. Anaplasma spp. infections were screened by microscopic examination and polymerase chain reaction targeting specific genes (msp4 gene for Anaplasma marginale and 16S rRNA gene for Anaplasma platys and Anaplasma bovis). Moreover, the associated risk factors for the infections were evaluated. Overall, blood samples from cattle revealed that 17.6% (33/187) were positive for Anaplasma spp. by microscopic examination and 20.8% (39/187) were positive by DNA amplification. Of these 20.8%, 17.6% were A. marginale and 3.2% were A. platys. However, A. bovis infection was not detected. Infection with Anaplasma spp. and A. marginale showed a significant association with breed and gender (p < 0.05) while age and packed cell volume levels showed no significant statistical relationship between Anaplasma spp. infected and uninfected animals. This study indicated that anaplasmosis is distributed in beef and dairy cattle in Thailand; therefore, prevention and control strategies for these pathogens should be improved. This information will benefit veterinarians and cowherds by avoiding vector exposure and eliminating tick breeding sites.