Many vector-borne diseases circulate in the Republic of Cabo Verde. These include malaria during the colonization of the archipelago by the Portuguese explorers and several arboviruses such as yellow fever (now eradicated), dengue and zika. To control these vector-borne diseases, an integrated vector control program was implemented. The main targeted mosquito vectors are Aedes aegypti and Anopheles arabiensis, and in a lesser extent the potential arbovirus vector Culex pipiens s.l. The main control strategy is focused on mosquito aquatic stages using diesel oil and Temephos. This latter has been applied in Cabo Verde since 1979. Its continuous use was followed by the emergence of resistance in mosquito populations. We investigated the current susceptibility to Temephos of the three potential mosquito vectors of Cabo Verde through bioassays tests. Our results showed various degrees of susceptibility with 24h post-exposure mortality rates ranging from 43.1% to 90.9% using WHO diagnostic doses. A full susceptibility was however observed with Bacillus thurigiensis var israelensis with mortality rates from 99.6% to 100%.
Background Due to the lack of vaccines, malaria control mainly involves the control of anopheline vectors (Anopheles spp.) using chemical insecticides. However, the prolonged and indiscriminate use of these compounds has led to the emergence of resistance in Anopheles populations in Africa. Insecticide resistance surveillance programs are less frequent in Cabo Verde than in other African countries. This study aimed to investigate the circulation of the L1014F and L1014S alleles in natural populations of Anopheles arabiensis collected from two sampling sites in the city of Praia, Cabo Verde. Methods Anopheles larvae were collected from the two sampling sites and reared in the laboratory until the adult stage. Mosquitoes were first morphologically identified by classical taxonomy and then by molecular species identification using molecular markers. All Anopheles arabiensis were subjected to PCR analysis to screen for mutations associated to resistance in the Nav gene. Results A total of 105 mosquitoes, all belonging to the Anopheles gambiae complex, were identified by classical taxonomy as well as by molecular taxonomy. Molecular identification showed that 100% of the An. gambiae senso lato specimens analyzed corresponded to An. arabiensis. Analysis of the Nav gene revealed the presence of L1014S and L1014F alleles with frequencies of 0.10 and 0.19, respectively. Conclusions Our data demonstrated, for the first time, the presence of the L1014F allele in the An. arabiensis population from Cabo Verde, as well as an increase in the frequency of the kdr L1014S allele reported in a previous study. The results of this study demonstrate the need to establish new approaches in vector control programs in Cabo Verde. Graphical Abstract
BackgroundDue to the lack of vaccines, malaria control mainly involves the control of the incriminated vector, Anopheles spp, using chemical insecticides. However, the prolonged and indiscriminate use of these compounds has led to the emergence of resistance in Anopheles populations from African continent. The surveillance of this resistance is more frequent in other African countries; however, Cabo Verde does not carry out this surveillance in the same way. Thus, this study aimed to investigate the circulation of the L1014F and L1014S alleles in natural populations of Anopheles arabiensis from the city of Praia, Cabo Verde. MethodsLarvae of Anopheles genus were collected in two areas of Praia and reared in the laboratory until maturity. Mosquitoes were morphologically identified by classical taxonomy and then, subjected to molecular species identification using molecular markers. All Anopheles arabiensis were subjected to PCR to screen for mutations associated to resistance in the Nav gene. ResultsA total of 105 mosquitoes, belonging to the Anopheles gambiae complex, were identified by classical taxonomy were also identified by molecular taxonomy. The molecular identification showed that 100% of the An. gambiae s.l. analyzed were An. arabiensis.. Analysis of the Nav gene revealed the presence of L1014S and L1014F alleles with frequencies of 0.14 and 0.23, respectively. ConclusionsOur data demonstrate, for the first time, the presence of the L1014F allele in the An. arabiensis population from Cabo Verde and an increase of the previously found Kdr L1014S allele. The results presented in this study demonstrate the need to establish new approaches in vector control programs in Cabo Verde.
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