Abstract
BackgroundKnowledge on the spread and distribution of insecticide resistance in major malaria vectors such as Anopheles funestus is key to implement successful resistance management strategies across Africa. Here, by assessing the susceptibility status of an inland population of An. funestus Giles (Kpome) and investigating molecular basis of resistance, we show that multiple resistance and consistent plasmodium infection rate are present in Anopheles funestus populations from Kpome.MethodsThe insecticide susceptibility level of collected Anopheles funestus was assessed. Synergist (PBO) was used to screen resistance mechanisms. The TaqMan technique was used for genotyping of insecticide resistant alleles and detecting plasmodium infection levels. The nested PCR was used to further assess the plasmodium infection rate.ResultsThe TaqMan analysis of plasmodial infections revealed an infection rate (18.2 %) of An. funestus in this locality. The WHO bioassays revealed a multiple phenotypic resistance profile for An. funestus in Kpome. This population is highly resistant to pyrethroids (permethrin and deltamethrin), organochlorines (DDT), and carbamates (bendiocarb). A reduced susceptibility was observed with dieldrin. Mortalities did not vary after pre-exposure to PBO for DDT indicating that cytochrome P450s play little role in DDT resistance in Kpome. In contrast, we noticed, a significant increase in mortalities when PBO was combined to permethrin suggesting the direct involvement of P450s in pyrethroid resistance. A high frequency of the L119F-GSTe2 DDT resistance marker was observed in the wild DDT resistant population (9 %RS and 91 %RR) whereas the A296S mutation was detected at a low frequency (1 %RS and 99 %SS).ConclusionThe presence of multiple resistance in An. funestus populations in the inland locality of Kpome is established in this study as recently documented in the costal locality of Pahou. Data from both localities suggest that resistance could be widespread in Benin and this highlights the need for further studies to assess the geographical distribution of insecticide resistance across Benin and neighboring countries as well as a more comprehensive analysis of the resistance mechanisms involved.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1723-y) contains supplementary material, which is available to authorized users.
Highlights
Knowledge on the spread and distribution of insecticide resistance in major malaria vectors such as Anopheles funestus is key to implement successful resistance management strategies across Africa
The dominant species of Plasmodium recorded in the population was P. falciparum (14 infected mosquitoes out of 93 tested) followed by P. ovale/ P. vivax/ P. malariae (P. ovm) which were found in two infected mosquitoes
The nested PCR performed on the same specimens revealed 11 mosquitoes infected by P. falciparum and one mosquito by P. malariae
Summary
Malaria remains an important health issue in Benin where it is the main cause of morbidity and mortality with children under five and pregnant women being the more vulnerable groups [1] In this country as across Africa, long lasting insecticide nets (LLINs) and bendiocarb based indoor residual spraying (IRS) are the key tools used for malaria control [1]. Resistance against the main insecticides used in public health, such as pyrethroids, carbamates or DDT is increasingly reported in An. funestus Giles populations [2,3,4,5] from southern Africa (Mozambique [2] and Malawi [6, 7]); East Africa (Uganda) [8, 9]; Central Africa (Cameroon) [2] and West Africa (Ghana, Benin [4, 10]). Complementary studies are required to assess the operational impact of the resistance on the efficacy/efficiency of vector control tools against malaria transmission and mortality/morbidity in local populations before giving any clear recommendation to malaria control programs
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
