Serological detection of Trypanosoma evansi infection in cattle using an in vitro cultivated antigen for indirect-ELISA in Thailand.

Trypanosoma evansi is a hemoflagellate protozoan primarily transmitted by blood-sucking insects, causing significant economic losses in livestock across Southeast Asia, Africa and South America, with seroprevalence ranging from 0 % to more than 80 %. In Thailand, most livestock infections are asymptomatic, making diagnosis and disease control challenging. The WOAH recommends using an iELISA with WCLAs for detecting latent infection. However, this method relies on experimental animals to produce antigens, leading to complexity, high costs, and ethical concerns. To address this, the present study utilized in in vitro-produced crude antigens in an iELISA to detect anti-T. evansi antibodies in cattle and compare with the reference test with in vivo T. evansi crude antigen. Examination of total 778 serum samples revealed individual and herd-level seroprevalence rates of 20.05 % and 60 %, respectively, indicating significant exposure to T. evansi. Seroprevalence varied geographically, with the highest rate in Suphanburi province and no cases detected in Tak and Ubon Ratchathani provinces. Multivariable logistic regression analysis showed that cattle from the central and northern regions had higher seroprevalence rates than those from the northeastern region, likely due to differences in vector distribution, farming practices, or environmental conditions. The iELISA using in vitro-produced antigens demonstrated comparable performance to in vivo-produced antigens (k = 0.500), confirming its potential as a reliable diagnostic tool. This study is the first to use in vitro-cultured T. evansi antigens for antibody detection in small-scale Thai livestock farms. The method offers several advantages, including improved standardization, cost-effectiveness, and ethical benefits by replacing the need for live animals in antigen production. The findings of this study provide essential information on the seroprevalence of T. evansi and associated risk factors in cattle in Thailand, thereby contributing to improved disease surveillance and control strategies.