Assessment of diagnostic doses for widely used synthetic pyrethroids (Deltamethrin & Permethrin) in an endemic focus of leishmaniasis in Turkey.

BACKGROUND: Leishmania is a group of parasitic flagellated protozoons, which are transmitted by female sand flies and produces health problems in humans and also in wild and domestic animals. So far, 25 Phlebotomus and 4 Sergentomyia species were recorded in Turkey including proven or possible vectors of Leishmania spp. As no single insecticide susceptibility test was conducted targeting the sand flies in Turkey, we aimed to determine the diagnostic dose against two commonly used synthetic pyrethroids (deltamethrin and permethrin) in a hyperendemic area for leishmaniasis.

METHODS: Sand flies were collected from villages of Adana in 2-4 September 2013 using Centers for Disease Control and Prevention (CDC) light traps and transferred to the laboratory. The World Health Organisation tube test method was conducted using self-prepared filter papers with different concentrations. In order to determine the diagnostic dose, lethal doses (LD) were calculated by EPA Probit Analysis. Sand flies used in the experiments were dissected, mounted and identified.

RESULTS: For the lowest (0.025 %) and highest dose of permethrin (0.5 %), the mortality rate was recorded as 52.6 % and 100 % by the end of 24-h period and the diagnostic dose was recorded as 0.36 %. The mortality rate for lowest (0.0025 %) and highest (0.05 %) doses of deltamethrin was recorded as 54.8 % and 100 %. The diagnostic dose of deltamethrin was determined as 0.9 %.

CONCLUSION: An insecticide susceptibility study was conducted in Turkey for the first time and effective doses were determined by calculating the LDs. According to presented results, the wild population of sand flies collected from a hyper-endemic region of Adana Province is still susceptible to deltamethrin and permethrin.