Evaluation of Trypanosama evansi prevalence and risk factors in the one-humped camels (Camelus dromedarius) of the north-east of Iran by a real-time PCR test.

The Surra caused by Trypanosoma evansi (T. evansi) is an economically damaging disease of livestock including camels, horses, and buffaloes. The disease is transmitted by arthropod flies belonging to family tabanidae. The clinical signs of affected animals include recurrent fever, progressive anemia, cachexia, edema, and abortion. In order to determine the point prevalence of Surra in the camel population of north-east of Iran, 152 blood samples from one-humped camels were collected by multiple cluster sampling methods from three provinces, namely, Razavi Khorasan (R.Kh.), Northern Khorasan (N.Kh.), and Southern Khorasan (S.Kh.). The nucleic acid extracted from the buffy coat of each blood sample was analyzed by SYBR green real-time PCR test for the detection of T. evansi in the blood samples. T. evansi was detected in 10 out of 152 camel blood samples (6.5%) with a prevalence rate of 8.6, 9.3, and 1.4 percent in R.Kh., N.Kh., and S.Kh. provinces, respectively. The prevalence of the disease decreased from north to south in the Khorasan provinces. Multivariate logistic regression analyses showed that among risk factors influencing Surra in the camel population, location was the most remarkable risk factor. Different geographical conditions, climate change, and the amount of raining can be considered as the factors affecting Surra vector population from north to south, resulting in a decrease in the rate of the prevalence of Surra from north to south.