Patterns Of Insecticide Resistance Among Anopheles Gambiae Mosquitoes In Five Districts In Uganda: 2011-2015

Abstract Background: Malaria ranks among the leading global public health challenges. Resistance to insecticides used in vector control by malaria vectors threatens the effectiveness of this intervention. We analyzed data from routine susceptibility tests conducted in sentinel sites in five Ugandan districts to determine the status and pattern of insecticide resistance among Anopheles gambiae mosquito vectors, and to assess the trend of mortality rates of the vector. Methods: We conducted a cross-sectional study using secondary data from sentinel sites in Apac, Kanungu, Hoima, Tororo, and Wakiso Districts of Uganda. Chemicals from different classes of insecticides were subjected to susceptibility tests, which included both the World Health Organization (WHO) standard test kit and the Centers for Disease Control and Prevention (CDC) bottle bioassay tests. Resistance was defined according to the standard WHO criteria of insecticide resistance. The Fisher’s Exact Test was used to determine the difference in mortality rates across years in the study period.Results: A total of eight chemicals were used in the selected districts over the years of study. Out of the 5 districts, we found that the average mortality rate of the mosquito vector by the carbamates was over 98% in 3 districts. In Tororo and Wakiso Districts, the average was about 90%. Mortality of mosquitoes by pyrethroids used averaged less than 80% in all five districts. The organochlorines averaged less than 50% in four out of five districts. In Apac District, organochlorines averaged a mortality rate of 94%. The organophosphates averaged 100% mortality in all sentinel sites. There was no specific pattern in mortality of Anopheles gambiae by insecticides.Conclusion: There was widespread resistance to pyrethroids and organochlorines, with patchy resistance observed against carbamates. Only organophosphates showed potency in all sentinel sites. This threatens gains made in malaria control, and renews calls for continued insecticide resistance monitoring.

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Insecticide resistance in Anopheles stephensi in Somali Region, eastern Ethiopia

10.21203/rs.2.18020/v3 ◽

2020 ◽

Author(s):

Solomon Yared ◽

Araya Gebressielasie ◽

Lambodhar Damodaran ◽

Victoria Bonnell ◽

Karen Lopez ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Stephensi ◽

Mortality Rates ◽

Resistance Mechanisms ◽

World Health ◽

Malaria Vectors ◽

Resistance Locus ◽

Eastern Ethiopia ◽

Pyrethroid Insecticides ◽

Pirimiphos Methyl

Abstract Background The movement of malaria vectors into new areas is a growing concern in the efforts to control malaria. The recent report of Anopheles stephensi in eastern Ethiopia has raised the necessity to understand the insecticide resistance status of the vector in the region to better inform vector-based interventions. The aim of this study was to evaluate insecticide resistance in An. stephensi in eastern Ethiopia using two approaches: 1) World Health Organization (WHO) bioassay tests in An. stephensi; and 2) genetic analysis of insecticide resistance genes in An. stephensi in eastern Ethiopia. Methods Mosquito larvae and pupae were collected from Kebri Dehar. Insecticide susceptibility of An. stephensi was tested withmalathion 5%, bendiocarb 0.1%, propoxur 0.1%, deltamethrin 0.05%, permethrin 0.75%, Pirimiphos-methyl 0.25% and DDT 4%, according to WHO standard protocols. In this study, the knockdown resistance locus (kdr) in the voltage gated sodium channel (vgsc) and ace1R locus in the acetylcholinesterase gene (ace-1) were analysed in An. stephensi. Results All An. stephensi samples were resistant to carbamates, with mortality rates of 23% and 21% for bendiocarb and propoxur, respectively. Adult An. stephensi was also resistant to pyrethroid insecticides with mortality rates 67% for deltamethrin and 53% for permethrin. Resistance to DDT and malathion was detected in An. stephensi with mortality rates of 32% as well as An. stephensi was resistance to pirimiphos-methyl with mortality rates 14%. Analysis of the insecticide resistance loci revealed the absence of kdr L1014F and L1014S mutations and the ace1R G119S mutation. Conclusion Overall, these findings support that An. stephensi is resistant to several classes of insecticides, most notably pyrethroids. However, the absence of the kdr L1014 gene may suggest non-target site resistance mechanisms. Continuous insecticide resistance monitoring should be carried out in the region to confirm the documented resistance and exploring mechanisms conferring resistance in An. stephensi in Ethiopia.

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Insecticide Resistance in Anopheles stephensi in Somali Region, Eastern Ethiopia

10.21203/rs.2.18020/v2 ◽

2020 ◽

Cited By ~ 1

Author(s):

Solomon Yared ◽

Araya Gebressielasie ◽

Lambodhar Damodaran ◽

Victoria Bonnell ◽

Karen Lopez ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Stephensi ◽

Mortality Rates ◽

Resistance Mechanisms ◽

World Health ◽

Malaria Vectors ◽

Eastern Ethiopia ◽

Pyrethroid Insecticides ◽

Pirimiphos Methyl ◽

Health Organization

Abstract Background: The movement of malaria vectors into new areas is a growing concern in the efforts to control malaria. The recent report of Anopheles stephensi in eastern Ethiopia has raised the necessity to understand the insecticide resistance status of the vector in the region to better inform vector-based interventions. The aim of this study was to evaluate insecticide resistance in An. stephensi in eastern Ethiopia using two approaches: 1) World Health Organization (WHO) bioassay tests in An. stephensi and 2) genetic analysis of insecticide resistance genes in An. stephensi in eastern Ethiopia. Methods: Mosquito larvae and pupae were collected from Kebridehar. Insecticide susceptibility of An. stephensi was tested with malathion 5%, bendiocarb 0.1%, propoxur 0.1%, deltamethrin 0.05%, permethrin 0.75%, Pirimiphos-methyl 0.25% and DDT 4%, according to WHO standard protocols. Results: All An. stephensi samples were resistant to carbamates, with mortality rates 23% and 21% for bendiocarb and propoxur, respectively. Adult An. stephensi was also resistant to pyrethroid insecticides with mortality rates 67% for deltamethrin and 53% for permethrin. Resistance to DDT and malathion was detected in An. stephensi with mortality rates of 32% as well as An. stephensi was resistance to pirimiphos-methyl with mortality rates 14%. Analysis of the voltage gate sodium channel gene (vgsc) revealed the absence of kdr L1014 mutations. Conclusion: Overall, these findings support that An. stephensi is resistant to several classes of insecticides, most notably pyrethroids. However, the absence of the kdr L1014 gene may suggest non-target site resistance mechanisms. Continuous insecticide resistance monitoring should be carried out in the region to confirm the documented resistance and exploring mechanisms conferring resistance in An. stephensi in Ethiopia.

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Malaria Transmission, Vector Diversity, and Insecticide Resistance at a Peri-Urban Site in the Forest Zone of Ghana

Frontiers in Tropical Diseases ◽

10.3389/fitd.2021.739771 ◽

2021 ◽

Vol 2 ◽

Author(s):

Yaw Akuamoah-Boateng ◽

Ruth C. Brenyah ◽

Sandra A. Kwarteng ◽

Patrick Obuam ◽

Isaac Owusu-Frimpong ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Gambiae ◽

Malaria Transmission ◽

Urban Setting ◽

World Health ◽

Malaria Vectors ◽

Urban Site ◽

Human Landing Catch ◽

Anopheles Coluzzii ◽

Anopheles Gambiae S.S

IntroductionRecent surge of Anopheles resistance to major classes of World Health Organization (WHO)-approved insecticides globally necessitates the need for information about local malaria vector populations. It is believed that insecticide efficacy loss may lead to operational failure of control interventions and an increase in malaria infection transmission. We investigated the susceptibility levels of malaria vectors to all classes of WHO-approved vector control insecticides and described the dynamics of malaria transmission in a peri-urban setting.MethodsFit 3–5-day-old adults that emerged from Anopheles larvae collected from several different sites in the study area were subjected to the WHO bioassay for detecting insecticide resistance. The knockdown resistance gene (kdr) mutations within the vector populations were detected using PCR. Entomological inoculation rates were determined using the human landing catch technique and Plasmodium falciparum circumsporozoite ELISA.ResultsThe malaria vectors from the study area were resistant to all classes of insecticides tested. Out of the 284 Anopheles complex specimen assayed for the resistance study, 265 (93.30%) were identified as Anopheles gambiae s.s. The kdr gene was detected in 90% of the Anopheles gambiae s.s. assayed. In an area where Anopheles coluzzii resistance to insecticides had never been reported, the kdr gene was detected in 78% of the Anopheles coluzzii sampled. The entomological inoculation rate (EIR) for the dry season was 1.44 ib/m/n, whereas the EIR for the rainy season was 2.69 ib/m/n.ConclusionsThis study provides information on the high parasite inoculation rate and insecticide resistance of malaria vectors in a peri-urban community, which is critical in the development of an insecticide resistance management program for the community.

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Characterization of resistance profile (intensity and mechanisms) of Anopheles gambiae in three communes of northern Benin, West Africa

Malaria Journal ◽

10.1186/s12936-021-03856-2 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Casimir Dossou Kpanou ◽

Hermann W. Sagbohan ◽

Fortuné Dagnon ◽

Germain G. Padonou ◽

Razaki Ossè ◽

...

Keyword(s):

Insecticide Resistance ◽

Vector Control ◽

Anopheles Gambiae ◽

High Intensity ◽

Mortality Rates ◽

Detoxification Enzymes ◽

Malaria Vectors ◽

Malaria Vector Control ◽

Biochemical Tests ◽

Diagnostic Dose

Abstract Background The selection and the spread of insecticide resistance in malaria vectors to the main classes of insecticides used in vector control tools are a major and ongoing challenge to malaria vector control programmes. This study aimed to determine the intensity of vector resistance to insecticides in three regions of Benin with different agro-ecological characteristics. Methods Larvae of Anopheles gambiae sensu lato (s.l.) were collected from September to November 2017 in different larval sites in three northern Benin communes: Parakou, Kandi and Malanville. Two to five-day-old, non-blood-fed, female mosquitoes were exposed to papers impregnated with deltamethrin, permethrin and bendiocarb at dosages of 1 × the diagnostic dose, 5 × and 10 × to determine the intensity of resistance in these vectors. Molecular frequencies of the kdr L1014F and ace-1R G119S insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled at each study site. Results Resistance to pyrethroids (permethrin and deltamethrin) was recorded in all three communes with mortality rates below 60% using the diagnostic dose (1x). The results obtained after exposure of An. gambiae to permethrin 10 × were 99% in Kandi, 98% in Malanville and 99% in Parakou. With deltamethrin 10x, mortality rates were 100% in Kandi, 96% in Malanville and 73% in Parakou. For the diagnostic dose of bendiocarb, suspected resistance was recorded in the communes of Malanville (97%) and Kandi (94%) while sensitivity was observed in Parakou (98%).Using the 10 × dose, mortality was 98% in Kandi, 100% in Malanville and 99% in Parakou. The frequencies of the kdr L1014F allele varied between 59 and 83% depending on the sites and species of the An. gambiae complex, while the frequency of the ace-1R G119S gene varied between 0 and 5%. Biochemical tests showed high levels of oxidase and esterase activity compared to the susceptible colony strain of An. gambiae sensu stricto (Kisumu strain). Conclusion Anopheles gambiae showed a generalized loss of susceptibility to permethrin and deltamethrin but also showed moderate to high intensity of resistance in different regions of Benin. This high intensity of resistance is a potential threat to the effectiveness of vector control.

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Insecticide susceptibility tests conducted in Kamhororo, Masakadza and Chilonga villages in Zimbabwe during the 2011 malaria period

Journal of Entomological and Acarological Research ◽

10.4081/jear.2012.e19 ◽

2012 ◽

Vol 44 (3) ◽

pp. 19 ◽

Cited By ~ 2

Author(s):

N. Lukwa ◽

S. Sande ◽

P. Munosiyei ◽

M. Zimba

Keyword(s):

Insecticide Resistance ◽

World Health Organization ◽

Anopheles Gambiae ◽

World Health ◽

Insecticide Susceptibility ◽

Lambda Cyhalothrin ◽

Percent Mortality ◽

Susceptibility Tests ◽

Health Organization ◽

Observation Times

Insecticide susceptibility tests using World Health Organization papers treated with 4% dichloro-diphenyl-trichloro-ethane (DDT), 0.05% deltamethrin, 0.05% lambda-cyhalothrin, 0.5% etofenprox, 0.15% cyfluthrin and 0.75% permethrin were conducted in Kamhororo, Masakadza and Chilonga villages, Zimbabwe. Three to 5-day old female Anopheles gambiae sensu lato adult mosquitoes were used. Deltamethrin knocked down 100% of the mosquitoes from Kamhororo, Masakadza and Chilonga at 35 min exposure. DDT did not knock down 100% of the mosquitoes from Kamhororo and Masakadza but did so in Chilonga. One hundred percent knockdown was achieved for cyfluthrin when exposed to mosquitoes from Kamhororo (60 min), Masakadza (25 min) and Chilonga (25 min). Etofenprox knocked down 100% of the mosquitoes collected from Kamhororo (30 min), Masakadza (30 min) and Chilonga (55 min). Knockdown of mosquitoes due to deltamethrin, DDT, cyfluthrin, permethrin; lambda-cyhalothrin and etofenprox were different at different observation times. One hundred percent mortality due to deltamethrin, DDT, etofenprox, lambdacyhalothrin and cyfluthrin was recorded for mosquitoes collected from all the 3 sites. One hundred percent mortality due to pemethrin was recorded for mosquitoes collected from Kamhororo and Chilonga but mortality was 98.5% for those collected from Masakadza. No knockdown or mortality occurred in the controls from each locality. The kd50 (knockdown of 50% of the mosquitoes) values were 24.4-73.7 min (DDT), 8-13 min (pemethrin), 9.4-16.3 min (cyfluthrin), 9.4-14.4 min (etofenprox), 8.7-13 min (lambda-cyhalothrin) and 12.1-15.9 min (deltamethrin). The kd90 (knockdown of 90% of the mosquitoes) values were 45.6-199.5 min (DDT), 14.7-26.5 min (pemethrin), 16.5-34.9 min (cyfluthrin), 21.8-24.4 min (etofenprox), 16.3-31.6 min (lambdacyhalothrin) and 21-25.3 min (deltamethrin). No insecticide resistance was recorded from the 3 sites.

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Insecticide Resistance in Anopheles stephensi in Somali Region, Eastern Ethiopia

10.21203/rs.2.18020/v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Solomon Yared ◽

Araya Gebressielasie ◽

Lambodhar Damodaran ◽

Victoria Bonnell ◽

Karen Lopez ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Stephensi ◽

Mortality Rates ◽

Resistance Mechanisms ◽

World Health ◽

Malaria Vectors ◽

Eastern Ethiopia ◽

Pyrethroid Insecticides ◽

Pirimiphos Methyl ◽

Health Organization

Abstract Background: The movement of malaria vectors into new areas is a growing concern in the efforts to control malaria. The recent report of Anopheles stephensi in eastern Ethiopia has raised the necessity to understand the insecticide resistance status of the vector in the region to better inform vector-based interventions. The aim of this study was to evaluate insecticide resistance in An. stephensi in eastern Ethiopia using two approaches: 1) World Health Organization (WHO) bioassay tests in An. stephensi and 2) genetic analysis of insecticide resistance genes in An. stephensi in eastern Ethiopia. Methods: Mosquito larava and pupae were collected from Kebridehar. Insecticide susceptibility of An. stephensi was tested with malathion 5%, bendiocarb 0.1%, propoxur 0.1%, deltamethrin 0.05%, permethrin 0.75%, Pirimiphos-methyl 0.25% and DDT 4%, according to WHO standard protocols. Results: All An. stephensi samples were resistant to carbamates, with mortality rates 23% and 21% for bendiocarb and propoxur, respectively. Adult An. stephensi was also resistant to pyrethroid insecticides with mortality rates 67% for deltamethrin and 53% for permethrin. Resistance to DDT and malathion was detected in An. stephensi with mortality rates of 32% as well as An. stephensi was resistance to pirimiphos-methyl with mortality rates 14%. Analysis of the voltage gate sodium channel gene (vgsc) revealed the absence of kdr L1014 mutations. Conclusion: Overall, these findings support that An. stephensi is resistant to several classes of insecticides, most notably pyrethroids. However, the absence of the kdr L1014 gene may suggest non-target site resistance mechanisms. Continued to insecticide resistance surveillance should be carried out in the region to confirm the findings on An. stephensi in Ethiopia.

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Molecular Detection of Insecticide Resistance Mutations in Anopheles gambiae from Sierra Leone Using Multiplex SNaPshot and Sequencing

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.666469 ◽

2021 ◽

Vol 11 ◽

Author(s):

Jianhai Yin ◽

Frederick Yamba ◽

Canjun Zheng ◽

Shuisen Zhou ◽

Samuel Juana Smith ◽

...

Keyword(s):

Insecticide Resistance ◽

Vector Control ◽

Anopheles Gambiae ◽

Sierra Leone ◽

Statistical Significance ◽

Indoor Residual Spraying ◽

Malaria Vectors ◽

Mosquito Vector ◽

Resistance Mutations ◽

African Countries

Vector control interventions including long-lasting insecticidal nets and indoor residual spraying are important for malaria control and elimination. And effectiveness of these interventions depends entirely on the high level of susceptibility of malaria vectors to insecticides. However, the insecticide resistance in majority of mosquito vector species across African countries is a serious threat to the success of vector control efforts with the extensive use of insecticides, while no data on insecticide resistance was reported from Sierra Leone in the past decade. In the present study, the polymerase chain reaction was applied for the identification of species of 757 dry adult female Anopheles gambiae mosquitoes reared from larvae collected from four districts in Sierra Leone during May and June 2018. And the mutations of kdr, rdl, ace-1 genes in An. gambiae were detected using SNaPshot and sequencing. As a result, one sample from Western Area Rural district belonged to Anopheles melas, and 748 An. gambiae were identified. Furthermore, the rdl mutations, kdr west mutations and ace-1 mutation were found. The overall frequency was 35.7%, 0.3%, 97.6% and 4.5% in A296G rdl, A296S rdl, kdrW and ace-1, respectively. The frequencies of A296G rdl mutation (P < 0.001), kdrW mutation (P = 0.001) and ace-1 mutation (P < 0.001) were unevenly distributed in four districts, respectively, while no statistical significance was found in A296S rdl mutation (P = 0.868). In addition, multiple resistance patterns were also found. In conclusion, multiple mutations involved in insecticide resistance in An. gambiae populations in Sierra Leone were detected in the kdrW, A296G rdl and ace-1 alleles in the present study. It is necessary to monitor vector susceptibility levels to insecticides used in this country, and update the insecticide resistance monitoring and management strategy.

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Insecticide resistance status of malaria vectors Anopheles gambiae (s.l.) of southwest Burkina Faso and residual efficacy of indoor residual spraying with microencapsulated pirimiphos-methyl insecticide

Parasites & Vectors ◽

10.1186/s13071-020-04563-8 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Dieudonné Diloma Soma ◽

Barnabas Zogo ◽

Domonbabele François de Sales Hien ◽

Aristide Sawdetuo Hien ◽

Didier Alexandre Kaboré ◽

...

Keyword(s):

Insecticide Resistance ◽

Burkina Faso ◽

Anopheles Gambiae ◽

Local Population ◽

Residual Activity ◽

Indoor Residual Spraying ◽

Susceptible Strain ◽

Malaria Vectors ◽

Pirimiphos Methyl ◽

Residual Efficacy

Abstract Background The rapid spread of insecticide resistance in malaria vectors and the rebound in malaria cases observed recently in some endemic areas underscore the urgent need to evaluate and deploy new effective control interventions. A randomized control trial (RCT) was conducted with the aim to investigate the benefit of deploying complementary strategies, including indoor residual spraying (IRS) with pirimiphos-methyl in addition to long-lasting insecticidal nets (LLINs) in Diébougou, southwest Burkina Faso. Methods We measured the susceptibility of the Anopheles gambiae (s.l.) population from Diébougou to conventional insecticides. We further monitored the efficacy and residual activity of pirimiphos-methyl on both cement and mud walls using a laboratory susceptible strain (Kisumu) and the local An. gambiae (s.l.) population. Results An. gambiae (s.l.) from Diébougou was resistant to DDT, pyrethroids (deltamethrin, permethrin and alphacypermethrin) and bendiocarb but showed susceptibility to organophosphates (pirimiphos-methyl and chlorpyrimiphos-methyl). A mixed-effect generalized linear model predicted that pirimiphos-methyl applied on cement or mud walls was effective for 210 days against the laboratory susceptible strain and 247 days against the local population. The residual efficacy of pirimiphos-methyl against the local population on walls made of mud was similar to that of cement (OR = 0.792, [0.55–1.12], Tukey’s test p-value = 0.19). Conclusions If data on malaria transmission and malaria cases (as measured trough the RCT) are consistent with data on residual activity of pirimiphos-methyl regardless of the type of wall, one round of IRS with pirimiphos-methyl would have the potential to control malaria in a context of multi-resistant An. gambiae (s.l.) for at least 7 months.

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The regulatory genome of the malaria vector Anopheles gambiae: integrating chromatin accessibility and gene expression

NAR Genomics and Bioinformatics ◽

10.1093/nargab/lqaa113 ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

José L Ruiz ◽

Lisa C Ranford-Cartwright ◽

Elena Gómez-Díaz

Keyword(s):

Gene Expression ◽

Transcriptional Regulation ◽

Anopheles Gambiae ◽

Mosquito Control ◽

Regulatory Elements ◽

Chromatin Accessibility ◽

Malaria Vectors ◽

Specific Gene ◽

Mosquito Vector ◽

Human Malaria

Abstract Anopheles gambiae mosquitoes are primary human malaria vectors, but we know very little about their mechanisms of transcriptional regulation. We profiled chromatin accessibility by the assay for transposase-accessible chromatin by sequencing (ATAC-seq) in laboratory-reared A. gambiae mosquitoes experimentally infected with the human malaria parasite Plasmodium falciparum. By integrating ATAC-seq, RNA-seq and ChIP-seq data, we showed a positive correlation between accessibility at promoters and introns, gene expression and active histone marks. By comparing expression and chromatin structure patterns in different tissues, we were able to infer cis-regulatory elements controlling tissue-specific gene expression and to predict the in vivo binding sites of relevant transcription factors. The ATAC-seq assay also allowed the precise mapping of active regulatory regions, including novel transcription start sites and enhancers that were annotated to mosquito immune-related genes. Not only is this study important for advancing our understanding of mechanisms of transcriptional regulation in the mosquito vector of human malaria, but the information we produced also has great potential for developing new mosquito-control and anti-malaria strategies.

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Insights into factors sustaining persistence of high malaria transmission in forested areas of sub-Saharan Africa: the case of Mvoua, South Cameroon

Parasites & Vectors ◽

10.1186/s13071-020-04525-0 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Dominique Mieguim Ngninpogni ◽

Cyrille Ndo ◽

Patrick Ntonga Akono ◽

Anicet Nguemo ◽

Amine Nguepi ◽

...

Keyword(s):

Anopheles Gambiae ◽

Malaria Transmission ◽

Anopheles Funestus ◽

Mortality Rates ◽

Molecular Techniques ◽

Sub Saharan Africa ◽

World Health ◽

Enzyme Linked Immunosorbent Assay ◽

Pyrethroid Insecticides ◽

Kisumu Strain

Abstract Background In Mvoua, a village situated in a forested area of Cameroon, recent studies have reported high prevalence of Plasmodium falciparum infection among the population. In order to understand factors that can sustain such a high malaria transmission, we investigated the biology of Anopheles vectors and its susceptibility to insecticides, as well as long-lasting insecticidal net (LLIN) coverage, use and bio-efficacy. Methods A longitudinal entomological survey was conducted from July 2018 to April 2019. Adult mosquitoes were collected using the human landing catch (HLC) method and identified using morphological and molecular techniques. Anopheles gambiae (s.l.) larvae were sampled from several stagnant water pools throughout the village and reared to generate F1 adults. The presence of P. falciparum circumsporozoite antigen was detected in the heads and thoraces of mosquitoes collected as adults using an enzyme-linked immunosorbent assay. The insecticide susceptibility status of the local An. gambiae (s.l.) F1 population to the pyrethroid insecticides deltamethrin 0.5% and permethrin 0.75% was determined using World Health Organization-tube bioassays, while the frequency of the knockdown resistance (kdr) mutation was determined by PCR. Coverage, use and physical integrity of LLINs were assessed in households, then cone assays were used to test for their bio-efficacy on both the reference insecticide-susceptible Kisumu strain and on field F1 An. gambiae (s.l.) Results In total, 110 Anopheles mosquitoes were collected, of which 59.1% were identified as Anopheles funestus (s.l.), 38.18% as An. gambiae (s.l.) and 2.72% as An. ziemanii. Anopheles funestus was the most abundant species except in the long rainy season, when An. gambiae (s.l.) predominated (65.8%). In the dry seasons, vectors were principally endophagous (76% of those collected indoors) while they tended to be exophagous (66% of those collected outdoors) in rainy seasons. High Plasmodium infection was observed in An. gambiae (s.l.) and An. funestus, with a circumsporozoitic rate of 14.29 and 10.77%, respectively. Anopheles gambiae (s.l.) was highly resistant to pyrethroid insecticides (mortality rates: 32% for permethrin and 5% for deltamethrin) and harbored the kdr-L1014F mutation at a high frequency (89.74%). Of the 80 households surveyed, only 47.69% had achieved universal coverage with LLNs. Around 70% of the LLINs sampled were in poor physical condition, with a proportionate hole index > 300. Of the ten LLNs tested, eight were effective against the An. gambiae reference insecticide-susceptible Kisumu strain, showing mortality rate of > 80%, while none of these LLINs were efficient against local An. gamabie (s.l.) populations (mortality rates < 11.5%). Conclusion A combination of elevated P. falciparum infection in Anopheles vector populations, insufficient coverage and loss of effectiveness of LLINs due to physical degradation, as well as high resistance to pyrethroid insecticides is responsible for the persistence of high malaria transmission in forested rural area of Mvoua, Cameroon.

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