Molecular detection of Trypanosoma evansi in dogs from India and Southeast Asia

Trypanosoma evansi, the causative agent of surra, is a hemoflagellate protozoan mechanically transmitted by hematophagous flies, mainly in tropical and subtropical regions. This protozoan affects several mammalian hosts, including dogs, which are highly susceptible to the infection. To investigate the occurrence of T. evansi in dogs, a total of 672 DNA samples from India (n = 228), Indonesia (n = 57), Malaysia (n = 45), the Philippines (n = 103), Thailand (n = 120), and Vietnam (n = 119) were screened by using species-specific conventional PCR. Of the tested dogs, 10 (1.5%) scored positive to T. evansi. In particular, positive samples were detected in canine blood samples collected from India (n = 4; 1.8%), Indonesia (n = 4; 7%), and Malaysia (n = 2; 4.4%). All tested samples from the Philippines, Thailand and Vietnam were negative. Nucleotide sequence analysis revealed a high variation (i.e. from 0.4% to 6.2%) among the RoTat 1.2 variant surface glycoprotein (vsg) gene. Although the number of sequences included in this analysis is relatively small, this nucleotide variation may indicate the divergence of T. evansi RoTat 1.2 vsg gene among different strains. The high incidence of T. evansi previously reported in cattle and buffaloes in India and Southeast Asia suggests that these animals are the main source of infection to dogs.