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

Abstract

Objective: To investigate species composition, density, accumulated degree day and diversity of sand flies during April to October 2010 in Azarshahr district, a new focus of visceral leishmaniasis in north western Iran. Methods: Sand flies were collected using sticky traps biweekly and were stored in 96% ethanol. All specimens were mounted in Pun's medium for species identification using valid keys of sandflies. The density was calculated by the formula: number of specimens/m(2) 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 the Shannon weaver formula (H'=Sigma(s)(i=1) Pi log(e) Pi). Results: Totally 5 557 specimens comprising 16 Species (14 Phlebotomus, and 2 Sergentomyia) were identified. The Activity of the species extended from April to October. Common sand-flies interesting places were Phlebotomus papatasi, Phlebotomus sergenti and Phlebotomus mongolensis. The monthly average density was 37.6, 4.11, 40.23, 30.38 and 30.67 for Almalodash, Jaragil, Segaiesh, Amirdizaj and Germezgol villages, respectively. Accumulated degree-day from early January to late May was approximately 289 degree days. The minimum threshold temperature for calculating of accumulated degree-day was 17.32 degrees C. According on the Shannon-weaver (H'), diversity of sand flies within are study were estimated as 0.917, 1.867, 1.339, 1.673, and 1.562 in Almalodash, Jaragil, Segaiesh, Amirdizaj and Germezgol villages, respectively. Conclusions: This study is the first detailes research in endemic focus of visceral leishmaniasis in Azarshahr district. The population of dynamics of sand flies in Azarshahr district were greatly affected by climatic factors. According to this study the help health authorities to predicate period of maximum risk of visceral leishmaniasis transmission and implement control program.