Kourosh Arzamani1, Hassan Vatandoost2, Yavar Rassi3, Mohammad Reza Abai3, Amir Ahmad Akhavan3, Mohammad Alavinia4, Kamran Akbarzadeh3, Mehdi Mohebali5, Sayena Rafizadeh6. 1. Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran; Vectorborne Diseases Research Center, North Khorasan University of Medical Sciences, Bojnurd, Iran. 2. Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences; Department of Environmental Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Silences, Tehran, Iran. 3. Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 4. Vectorborne Diseases Research Center, North Khorasan University of Medical Sciences, Bojnurd, Iran; Toronto Rehabilitation Centre, University Health Network, Toronto, Canada. 5. Department of Medical Parasitology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 6. Ministry of Health and Medical Education, National Institute for Medical Research Development (NIMAD), Tehran, Iran.
Abstract
BACKGROUND & OBJECTIVES: Phlebotomine sandflies (Diptera: Psychodidae) transmit several important zoonotic diseases to humans and leishmaniasis is one of them. Two types of leishmaniasis, viz. visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) are endemic in Iran. The main vector of anthroponotic cutaneous leishmaniasis (ACL) is Phlebotomus sergenti. The aim of the present study was to determine the susceptibility status of wild strain of P. sergenti to different imagicides of DDT, bendiocarb and permethrin at the median lethal time, LT50 level. METHODS: Sandflies were collected from selected village in North Khorasan Province, northeast of Iran from indoors using CDC light-traps. Susceptibility test was carried out against DDT (4%), bendiocarb (0.1%) and permethrin (0.75%) for all the females according to WHO method, and mortality was calculated. Species identification was carried out using the morphological keys. Data were analysed using probit regression analysis to determine the LT50 and LT90 values. RESULTS: In total, 851 female P. sergenti sandflies were tested. LT50 values to DDT (4%), Bendiocarb (0.1%) and permethrin (0.75%) were 15.4, 19.2 and 6.3 min respectively. The values for LT90 were 51.1, 47.4 and 18.6 min respectively. The mortality rates for 1 h exposure time to DDT, bendiocarb and permethrin were 89.8 ± 1.4; 93.6 ± 1.4; and 95.6 ± 1.7%, respectively. INTERPRETATION & CONCLUSION: The suscesptibility studies revealed development of resistance against DDT (4%) in the wild strain of P. sergenti population. Monitoring and mapping of insecticide resistance in the region is recommended for vector control.
BACKGROUND & OBJECTIVES: Phlebotomine sandflies (Diptera: Psychodidae) transmit several important zoonotic diseases to humans and leishmaniasis is one of them. Two types of leishmaniasis, viz. visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) are endemic in Iran. The main vector of anthroponotic cutaneous leishmaniasis (ACL) is Phlebotomus sergenti. The aim of the present study was to determine the susceptibility status of wild strain of P. sergenti to different imagicides of DDT, bendiocarb and permethrin at the median lethal time, LT50 level. METHODS: Sandflies were collected from selected village in North Khorasan Province, northeast of Iran from indoors using CDC light-traps. Susceptibility test was carried out against DDT (4%), bendiocarb (0.1%) and permethrin (0.75%) for all the females according to WHO method, and mortality was calculated. Species identification was carried out using the morphological keys. Data were analysed using probit regression analysis to determine the LT50 and LT90 values. RESULTS: In total, 851 female P. sergenti sandflies were tested. LT50 values to DDT (4%), Bendiocarb (0.1%) and permethrin (0.75%) were 15.4, 19.2 and 6.3 min respectively. The values for LT90 were 51.1, 47.4 and 18.6 min respectively. The mortality rates for 1 h exposure time to DDT, bendiocarb and permethrin were 89.8 ± 1.4; 93.6 ± 1.4; and 95.6 ± 1.7%, respectively. INTERPRETATION & CONCLUSION: The suscesptibility studies revealed development of resistance against DDT (4%) in the wild strain of P. sergenti population. Monitoring and mapping of insecticide resistance in the region is recommended for vector control.