A survey of sandflies in the affected areas of leishmaniasis, southern Thailand

Leishmania siamensis was firstly described as a causative agent of autochthonous visceral leishmaniasis in southern provinces of Thailand since 2008. The spread of leishmaniasis depends on the distribution of the vectors and reservoir hosts. Unfortunately, little is known about these vital factors. The objective of this study was to identify the distribution of sandfly species, their density, and their habitats in the affected areas of leishmaniasis, southern Thailand. A cross-sectional survey of sandflies was conducted in three provinces of southern Thailand where leishmaniasis cases were previously reported. The collection of sandflies was performed using CDC light traps for four consecutive months, from March to June 2009. A total of 2,698 sandflies were collected in the affected areas. Among 1,451 female sandflies, six species of genus Sergentomyia were identified, i.e., Sergentomyia gemmea, Sergentomyia iyengari, Sergentomyia barraudi, Sergentomyia indica, Sergentomyia silvatica, and Sergentomyia perturbans. S. gemmea (81.4 %) was the most predominant species in all areas. In addition, one species of the genus Phlebotomus, Phlebotomus argentipes, a known vector of leishmaniasis was also detected. The distribution of sandfly species in these leishmaniasis-affected areas was different from the previous studies in other areas of Thailand. Further studies are needed to proof whether these sandflies can be the natural vectors of leishmaniasis.