Impact of land-use on malaria transmission in the Plateau region, southeastern Benin

BACKGROUND: The goal of the study is to investigate if local agricultural practices have an impact on malaria transmission in four villages located in the same geographical area within a radius of 15 kilometers. Among the villages, one (Itassoumba) is characterized by the presence of a large market garden and fishpond basins, the three others (Itakpako, Djohounkollé and Ko-koumolou) are characterized by traditional food-producing agriculture. METHODS: Malaria transmission was evaluated using human-landing catches, both indoors and outdoors, two nights per month for 12 months. Field collected females An. gambiae s.l. were exposed for 1 hour to 0.75% permethrin and 0.05% deltamethrin using WHO insecticide susceptibility test kits and procedures. The presence of the kdr mutation was analyzed by PCR. RESULTS: Anopheles gambiae s.s form M (93.65%), was identified as the main malaria vector. Its susceptibility level to pyrethroids was the same (p > 0.05) in all villages. kdr mutation frequencies are 81.08 in Itakpako, 85 in Itassoumba, 79.73 in Djohounkollé and 86.84 in Ko-Koumolou (p = 0.63). The entomological inoculation rate ranged from 9.62 to 21.65 infected bites of An. gambiae per human per year in Djohounkollé, Itakpako and Ko-Koumolou against 1159.62 in Itassoumba (p < 0.0001). CONCLUSION: The level of resistance of An. gambiae to pyrethroids was the same in the four villages. The heterogeneous character of malaria epidemiology was confirmed. The creation of fishponds basins and the development of market-gardening activities increased drastically the malaria transmission in Itassoumba.