Abstract
Background: To optimize the success of insecticide-based malaria control intervention, knowledge of the distribution of Anopheles gambiae species and insecticide resistance mechanisms is necessary. This paper reported an updated data on pyrethroids/DDT resistance in the An. gambiae s.l population from Togo. Methods: From December 2013 to April 2015, females of indoor-resting An. gambiae s.l were captured in three locations belonging to three different ecological zones. Resistance to DDT, permethrin and deltamethrin was screened in F1 progeny of collected mosquitoes using WHO susceptibility tests. The identification of species of An. gambiae complex and the detection of kdr and ace.1 R allele were carried out using DNA-based molecular techniques. Results:An. gambiae from Kovié and Nangbéto were highly resistant to DDT and permethrin with mortalities rate ranging from 0.83% to 1.58% for DDT and zero to 8.54% for permethrin. Mosquitoes collected in Nangbéto displayed 81.53% mortality with deltamethrin. An. coluzzii and An. gambiae s.s were found in sympatry in Nangbéto and Mango . The allelic frequency of L1014F was high, ranging from 66 to 100% in both An. coluzzii and An. gambiae s.s. For the first time we detected the L1014S allele in both An. coluzzii and An. gambiaes.s. from Togo at the frequency ranging from 5% to 13% in all the sites. The kdr N1575Y was present at various frequencies in both species ranging from 10% to 45%. Both An. gambiae s.s. and An. coluzzii shared the ace1 R mutation in all investigated sites with allelic frequency ranging from 4% to 16%. Conclusion: These results showed that multiple mutations are involved in insecticides resistance in An. gambiae populations from Togo including the kdr L1014F, L1014S, and N1575Y and ace.1 R G119S mutations.
Highlights
Despite a reported decline in infection and mortality, malaria remains the fourth leading cause mortality in children under-five in the sub-region[1]
Studies have demonstrated the appearance of the N1575Y mutation as an additional resistance mechanism that appears with the L1014F kdr mutation
This study provides an update on current levels of resistance to permethrin and deltamethrin and frequencies of the kdr and ace.1R mutation in An. coluzzii and An. gambiae s.s in rural areas of Togo
Summary
Despite a reported decline in infection and mortality, malaria remains the fourth leading cause mortality in children under-five in the sub-region[1]. In Anopheles gambiae complex, kdr gene mutations, including the substitutions of leucine to phenylalanine (L1014F) and leucine to serine (L1014S), are the two mutations involved in the target site resistance[12,13]. These two target site mutations are largely distributed across the African Continent, yet differences in the allelic frequency have been reported between An. gambiae s.l. species and between breeding sites[3,14,15]. To optimize the success of insecticide-based malaria control intervention, knowledge of the distribution of Anopheles gambiae species and insecticide resistance mechanisms is necessary. The identification of species of An. gambiae complex and the detection of kdr and ace.1R allele were carried out using DNA-based molecular techniques
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