Widespread molecular evidence of Trypanosoma evansi among asymptomatic dogs in Iran.

Despite the widespread distribution of Trypanosoma evansi in camels and horses in Iran, only a few case reports of canine infection are available. We investigated the prevalence of trypanosomosis in 423 apparently healthy sheltered stray and owned dogs from five provinces representing different climatic regions of Iran (Hamedan, Kermanshah, Mazandaran, Yazd, and Khuzestan). Blood samples were examined microscopically and analyzed by PCR targeting the RoTat 1.2 variant surface glycoprotein (VSG) gene of T. evansi. RoTat-PCR detected T. evansi DNA in 97 dogs (22.9%), with provincial prevalences ranging from 7.5% to 39.0%; representative amplicons were confirmed by sequencing and phylogenetic analysis. No trypomastigotes were detected by microscopic examination. This study provides the first molecular evidence of T. evansi DNA in dogs from Iran and demonstrates widespread molecular detection of T. evansi among clinically healthy dogs. These findings suggest that exposure of dogs to T. evansi in endemic regions may be more common than previously recognized. However, the epidemiological significance of PCR-positive dogs remains uncertain. Future studies integrating parasite isolation, genomic characterization, longitudinal monitoring, and transmission investigations will be essential to determine the biological significance of these molecular findings and to clarify the epidemiological significance of asymptomatic PCR-positive dogs.