Prevalence of Trypanosoma evansi in horses in Israel evaluated by serology and reverse dot blot

Trypanosoma evansi is the cause of surra in horses, camels and other domestic animals. Following the first outbreak of surra in horses and camels in Israel in 2006, a survey of the prevalence of the parasite in the Israeli horse population was conducted using serology, PCR followed by the reverse dot blot (RDB) technique and blood smear microscopy. In total, 614 horses from 7 regions were sampled. The CATT/T. evansi kit was used for serology for all the horses. Horses from the Arava and Dead Sea region, where the first outbreak occurred, were sampled again one year later and both samples were subjected to serology and the RDB technique. The country wide seroprevalence was 4.6% (28/614). The seroprevalence in the Arava and Dead Sea region was 6.5% (9/139) in the first sampling compared with 4.1% (5/122) in the second, whereas the prevalence of RDB-positivity was 18.7% (26/139) in the first sampling and only 0.8% (1/122) in the second. All horses were asymptomatic except for one horse from the Arava and Dead Sea region that demonstrated clinical signs of surra combined with positive serology and RDB. The results of this study indicated that surra is prevalent in most regions of the country and thus should be considered an important differential diagnosis in horses and other domestic animals in Israel with chronic weight loss, edema or neurological signs.