Phenology and population dynamics of sand flies in a new focus of visceral leishmaniasis in Eastern Azarbaijan Province, North western of Iran

摘要

Objective:To investigate species composition, density, accumulated degree-day and diversity of sand flies during April to October2010in Azarshahr district, a new focus of visceral leishmaniasis in north western Iran.Methods: Sand flies were collected using sticky traps biweekly and were stored in96% ethanol. All specimens were mounted in Puri's medium for species identification using valid keys of sandflies. The density was calculated by the formula: number of specimens/m2 of sticky traps and number of specimens/ number of traps. Degree-day was calculated as follows: (Maximum temperature + Minimum temperature)/2-Minimum threshold. Diversity indices of the collected sand flies within different villages were estimated by s the Shannon- weaver formula (H'=ΣPilogePi i=1 ).Results:Totally5 557 specimens comprising 16Species (14Phlebotomus, and 2Sergentomyia) were indentified. The activity of the species extended from April to October. Common sand-flies in resting places werePhlebotomus papatasi, Phlebotomus sergenti andPhlebotomus mongolensis. The monthly average density was 37.6, 41.1, 40.23, 30.38 and30.67 for Almalodash, Jaragil, Segaiesh, Amirdizaj and Germezgol villages, respectively. Accumulated degree-day from early January to late May was approximately289 degree days. The minimum threshold temperature for calculating of accumulated degree-day was17.32℃. According on the Shannon-weaver (H'), diversity of sand flies within area study were estimated as0.917, 1.867, 1.339, 1.673, and1.562in Almalodash, Jaragil, Segaiesh, Amirdizaj and Germezgol villages, respectively.Conclusions: This study is the first detailed research in terms of species composition, density, accumulated degree-day and diversity of sand flies in an endemic focus of visceral leishamaniasis in Azarshahr district. The population dynamics of sand flies in Azarshahr district were greatly affected by climatic factors. According to this study the highest activity of the collected sand fly species occurs at the teritary week of August. It could help health authorities to predicate period of maximum risk of visceral leishamaniasis transmission and implement control program.