Authors

S Tehseen¹; N Jahan¹;  ¹ Govt College University, Pakistan

Discussion

Surra is a vector borne disease of animals and has a worldwide distribution. Trypanosoma evansi, the causative agent, principally transmitted by hematophagous flies. It is associated with great economic losses, working capacity, and productivity of animals. Recently reported Surra in Camels of Cholistan desert from our laboratory necessitated to find the vectors in selected areas. In current study field collection of vectors was done directly from the same camel herds investigated for surra. The collection was done twice a month from January 2012 to December 2013. Flies were identified morphologically by using taxonomic keys for Tabanidae, Stomoxys and Hematobia. Random samples (n=100) of flies per species, collected from the field diagnosed camels for Surra were examine for the signs of engorgements. Molecular identification was carried out on whole flies and fly body parts mid-guts and mouthparts following DNA extraction. TBR1/2 PCR and RoTat 1.2 PCR were carried out for the diagnosis of trypanosomes. Cytochrome b PCR was carried out on all samples for the evaluation of DNA quality. Blood meal analyses were also carried out by amplification of Cytochrome b genes and PCR products were purified and sequenced. A total of 4517 flies (tabanids, Hematobia and Stomoxys) were collected during the study period comprising T. rubidus (18.6%), T. striatus (37.8%) and S. calcitrans (43.6%). The total fly catch of each species was non-significantly different from each other (p < 0.05). Hematobia sp. were the most common flies found on camels. No significant difference was found between collected males and females of S. calcitrans (p > 0.05) while 100% collected population of T. rubidus and T. striatus comprised of females only. Seasonal variations in abundance of different flies peaks were irregularly distributed. T. rubidus population peaked in May and September and decreased after October. T. striatus was increased in July onwards before disappearing in November, 2013. Stomoxys were seen throughout 2012 and 2013 with three peaks in April, July and September 2012 whereas, two peaks were observed in the months of June and August in 2013. A significant difference was observed in S. calcitrans populations in summer and spring having higher abundance than autumn and winter (p < 0.05). The apparent and relative abundance of T. rubidus, T. striatus and S. calcitrans on camels is suggestive of their role as a mechanical vector of surra in Punjab Pakistan. The current study is a first and novel work related with recently reported study in our laboratory on the prevalence of surra in camels of Cholistan desert, Pakistan.