scholarly journals Pyrethroid Resistance in Anopheles gambiae Not Associated with Insecticide-Treated Mosquito Net Effectiveness Across Sub-Saharan Africa

2021 ◽  
Author(s):  
David A. Larsen ◽  
Rachael L. Church
Keyword(s):  
Anopheles Gambiae ◽  
Malaria Vector ◽  
Malaria Infection ◽  
Pyrethroid Resistance ◽  
Sub Saharan Africa ◽  
Malaria Vector Control ◽  
Lr Test ◽  
Meta Regression ◽  
Sub Saharan ◽  
The Impact

Pyrethroid resistance is a major concern for malaria vector control programs that predominantly rely on insecticide-treated mosquito nets (ITNs). Contradictory results of the impact of resistance have been observed during field studies. We combined continent-wide estimates of pyrethroid resistance in Anopheles gambiae from 2006 to 2017, with continent-wide survey data to assess the effect of increasing pyrethroid resistance on the effectiveness of ITNs to prevent malaria infections in sub-Saharan Africa. We used a pooled-data approach and a meta-regression of survey regions to assess how pyrethroid resistance affects the association between ITN ownership and malaria outcomes for children 6 to 59 months of age. ITN ownership reduced the risk of malaria outcomes according to both the pooled and meta-regression approaches. According to the pooled analysis, there was no observed interaction between ITN ownership and estimated level of pyrethroid resistance (likelihood ratio [LR] test, 1.127 for malaria infection confirmed by the rapid diagnostic test, P = 0.2885; LR test = 0.161 for microscopy-confirmed malaria infection, P = 0.161; LR test = 0.646 for moderate or severe anemia, P = 0.4215). Using the meta-regression approach to determine the level of pyrethroid resistance did not explain any of the variance in subnational estimates of ITN effectiveness for any of the outcomes. ITNs decreased the risk of malaria independent of the levels of pyrethroid resistance in malaria vector populations.

scholarly journals Pyrethroid resistance in Anopheles gambiae not associated with insecticide-treated mosquito net effectiveness across sub-Saharan Africa

2020 ◽  
Author(s):  
David A. Larsen ◽  
Rachael L. Church
Keyword(s):  
Anopheles Gambiae ◽  
Malaria Vector ◽  
Malaria Infection ◽  
Pyrethroid Resistance ◽  
Sub Saharan Africa ◽  
Malaria Vector Control ◽  
Lr Test ◽  
Meta Regression ◽  
Sub Saharan ◽  
The Impact

AbstractBackgroundPyrethroid resistance is a major concern for malaria vector control programs that predominantly rely on insecticide-treated mosquito nets (ITN). Contradictory results of the impact of resistance have been observed in field studies.MethodsWe combined continent-wide estimates of pyrethroid resistance in Anopheles gambiae from 2006-2017 with continent-wide survey data to assess the effect of increasing pyrethroid resistance on the effectiveness of ITNs to prevent malaria infections in sub-Saharan Africa. We utilized both a pooled-data approach and meta-regression of survey regions to assess how pyrethroid resistance affects the association between ITN ownership and malaria outcomes in children aged 6-59 months.FindingsITN ownership reduced the risk of malaria outcomes in both pooled and meta-regression approaches. In the pooled analysis, there was no observed interaction between ITN ownership and estimated level of pyrethroid resistance (Likelihood ratio [LR] test = 1.127 for the outcome of rapid diagnostic test confirmed malaria infection, p = 0.2885; LR test = 0.161 for the outcome of microscopy confirmed malaria infection, p = 0.161; LR test = 0.646 for the outcome of moderate or severe anemia, p = 0.4215). In the meta-regression approach the level of pyrethroid resistance did not explain any of the variance in subnational estimates of ITN effectiveness for any of the outcomes.InterpretationITNs decreased risk of malaria outcomes independent of the levels of pyrethroid resistance in the malaria vector populations.FundingDAL did not receive funding and RC received a SOURCE grant from Syracuse University for this project.

scholarly journals A pyrethroïd-treated bed net increases host attractiveness for Anopheles gambiae s.s. carrying the kdr allele in a dual-choice olfactometer

2016 ◽  
Author(s):  
Angélique Porciani ◽  
Malal Diop ◽  
Nicolas Moiroux ◽  
Tatiana Kadoke-Lambi ◽  
Anna Cohuet ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Anopheles Gambiae S.S ◽  
Host Seeking ◽  
Seeking Behavior ◽  
Sub Saharan ◽  
The Impact

AbstractThe use of long lasting insecticide nets (LLINs) treated with pyrethroïd is known for its major contribution in malaria control. However, LLINs are suspected to induce behavioral changes in malaria vectors, which may in turn drastically affect their efficacy against Plasmodium sp. transmission. In sub Saharan Africa, where malaria imposes the heaviest burden, the main malaria vectors are widely resistant to pyrethroïds, the insecticide family used on LLINs, which also threatens LLIN efficiency. There is therefore a crucial need for deciphering how insecticide-impregnated materials might affect the host-seeking behavior of malaria vectors in regards to insecticide resistance. In this study, we explored the impact of permethrin-impregnated net on the host attractiveness for Anopheles gambiae mosquitoes, either susceptible to insecticides, or carrying the insecticide resistance conferring allele kdr. Groups of female mosquitoes were released in a dual-choice olfactometer and their movements towards an attractive odor source (a rabbit) protected by insecticide-treated (ITN) or untreated nets (UTN) were monitored. Kdr homozygous mosquitoes, resistant to insecticides, were more attracted by a host behind an ITN than an UTN, while the presence of insecticide on the net did not affect the choice of susceptible mosquitoes. These results suggest that permethrin-impregnated net is detectable by malaria vectors and that the kdr mutation impacts their response to a LLIN protected host. We discuss the implication of these results for malaria vector control.

scholarly journals Investigating the relationship between insecticide resistance, underlying molecular mechanisms and malaria prevalence in Anopheles gambiae s.l. from Guinea

2018 ◽  
Author(s):  
Emma Collins ◽  
Natasha M. Vaselli ◽  
Moussa Sylla ◽  
Abdoul H. Beavogui ◽  
James Orsborne ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Molecular Mechanisms ◽  
Pyrethroid Resistance ◽  
Resistance Mechanisms ◽  
Malaria Prevalence ◽  
Sub Saharan Africa ◽  
Malaria Vector Control ◽  
Partial Restoration ◽  
Sub Saharan

AbstractThe threat of insecticide resistance across sub-Saharan Africa is anticipated to severely impact the continued effectiveness of malaria vector control. We investigated the effect of carbamate and pyrethroid resistance on Anopheles gambiae s.l age, Plasmodium falciparum infection and characterized molecular resistance mechanisms in Guinea. Pyrethroid resistance was intense, with survivors of ten times the insecticidal concentration required to kill susceptible individuals. The L1014F kdr allele was significantly associated with mosquito survival following deltamethrin or permethrin treatment (p=0.003 and p=0.04, respectively). N1575Y and I1527T mutations were identified in 13% and 10% of individuals, respectively, but neither conferred increased pyrethroid tolerance. Partial restoration of pyrethroid susceptibility following synergist pre-exposure suggest a role for mixed-function oxidases. Carbamate resistance was lower and significantly associated with the G119S Ace-1 mutation (p=0.001). Oocyst rates were 6.8% and 4.2% among resistant and susceptible mosquitoes, respectively; survivors of bendiocarb exposure were significantly more likely to be infected (p=0.03). Resistant mosquitoes had significantly lower parity rates; however, a subset of intensely pyrethroid-resistant vectors were more likely to be parous (p=0.042 and p=0.045, for survivors of five and ten times the diagnostic dose of insecticides, respectively). Our findings emphasize the need for additional studies directly assessing the influence of insecticide resistance on mosquito fitness.

scholarly journals Characterizing Permethrin and Etofenprox Resistance in Two Common Laboratory Strains of Anopheles gambiae (Diptera: Culicidae)

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 146 ◽  
Author(s):  
Aaron Gross ◽  
Jeffrey Bloomquist
Keyword(s):  
Anopheles Gambiae ◽  
Pyrethroid Resistance ◽  
Laboratory Strain ◽  
Pyrethroid Insecticide ◽  
Sub Saharan Africa ◽  
Cross Resistance ◽  
Type I ◽  
Mosquito Vector ◽  
Sub Saharan ◽  
Anopheles Gambiae Giles

Anopheles gambiae Giles (Diptera: Culicidae) is the most prolific malaria vector in sub-Saharan Africa, where widespread insecticide resistance has been reported. An. gambiae laboratory strains are commonly used to study the basic biology of this important mosquito vector, and also in new insecticide discovery programs, where insecticide-susceptible and -resistant strains are often used to screen new molecules for potency and cross-resistance, respectively. This study investigated the toxicity of permethrin, a Type-I pyrethroid insecticide, and etofenprox, a non-ester containing pyrethroid insecticide, against An. gambiae at three life stages. This characterization was performed with susceptible (G3; MRA-112) and resistant (Akdr; MRA-1280) An. gambiae strains; the Akdr strain is known to contain the L1014F mutation in the voltage-sensitive sodium channel. Surprisingly, etofenprox displays a lower level of resistance than permethrin against all stages of mosquitoes, except in a headless larval paralysis assay designed to minimize penetration factors. In first-instar An. gambiae larvae, permethrin had significant resistance, determined by the resistance ratio (RR50 = 5), but etofenprox was not significantly different (RR50 = 3.4) from the wild-type strain. Fourth-instar larvae displayed the highest level of resistance for permethrin (RR50 = 108) and etofenprox (RR50 = 35). Permethrin (PC50 = 2 ppb) and etofenprox (PC50 = 9 ppb) resulted in headless larval paralysis (5-h), but resistance, albeit lower, was still present for permethrin (RR50 = 5) and etofenprox (RR50 = 6.9). In adult female mosquitoes, permethrin displayed higher resistance (RR50 = 14) compared to etofenprox (RR50 = 4.3). The level of etofenprox resistance was different from that previously reported for a similar Akron An. gambiae laboratory strain (MRA-913). The chemical synergists piperonyl butoxide (PBO) and diethyl maleate (DEM) were able to synergize permethrin, but not etofenprox in the resistant strain (Akdr). In conclusion, multiple mechanisms are likely involved in pyrethroid resistance, but resistance profiles are dependent upon selection. Etofenprox is an effective insecticide against An. gambiae in the lab but will likely suffer from resistance in the field.

scholarly journals Bacterial larvicides used for malaria vector control in sub-Saharan Africa: review of their effectiveness and operational feasibility

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Yahya A. Derua ◽  
Eliningaya J. Kweka ◽  
William N. Kisinza ◽  
Andrew K. Githeko ◽  
Franklin W. Mosha
Keyword(s):  
Vector Control ◽  
Malaria Vector ◽  
Sub Saharan Africa ◽  
Malaria Vector Control ◽  
Sub Saharan

scholarly journals Pyrethroid Resistance in Anopheles gambiae, in Bomi County, Liberia, Compromises Malaria Vector Control

PLoS ONE ◽  
2012 ◽  
Vol 7 (9) ◽  
pp. e44986 ◽  
Author(s):  
Emmanuel A. Temu ◽  
Caroline Maxwell ◽  
Godwil Munyekenye ◽  
Annabel F. V. Howard ◽  
Stephen Munga ◽  
...  
Keyword(s):  
Vector Control ◽  
Anopheles Gambiae ◽  
Malaria Vector ◽  
Pyrethroid Resistance ◽  
Malaria Vector Control

scholarly journals Development of an Insecticide-Free Trapping Bednet to Control Mosquitoes and Manage Resistance in Malaria Vector Control: A New Way of Thinking

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 732
Author(s):  
Chouaibou S. Mouhamadou ◽  
Kun Luan ◽  
Behi K. Fodjo ◽  
Andre J. West ◽  
Marian G. McCord ◽  
...  
Keyword(s):  
Mosquito Control ◽  
Pyrethroid Resistance ◽  
Three Dimensional ◽  
Field Testing ◽  
Sub Saharan Africa ◽  
Malaria Vector Control ◽  
Worst Case ◽  
Crowd Modeling ◽  
Single Chemical ◽  
Sub Saharan

Mosquito-borne malaria kills 429,000 people each year with the problem being acute in sub-Saharan Africa. The successes gained with long-lasting pyrethroid-treated bednets are now in jeopardy because of wide-spread, pyrethroid resistance in mosquitoes. Using crowd modeling theory normalized for standard bednet architecture, we were able to design an attract–trap–kill technology for mosquitoes that does not require insecticides. Using three-dimensional polyester knitting and heat fixation, trap funnels were developed with high capture efficacy with no egression under worst-case laboratory conditions. Field testing in Africa in WHO huts with Gen1-3 T (trap)-Nets validated our model, and as predicted, Gen3 had the highest efficacy with a 4.3-fold greater trap–kill rate with no deterrence or repellency compared to Permanet 2.0, the most common bednet in Africa. A T-Net population model was developed based on field data to predict community-level mosquito control compared to a pyrethroid bednet. This model showed the Gen3 non-insecticidal T-Net under field conditions in Africa against pyrethroid resistant mosquitoes was 12.7-fold more efficacious than single chemical, pyrethroid-treated nets.

Justifying an Intentional Species Extinction: The Case of Anopheles gambiae

2021 ◽  
Author(s):  
Daniel Edward Callies ◽  
Yasha Rohwer
Keyword(s):  
Anopheles Gambiae ◽  
Malaria Vector ◽  
Malaria Parasite ◽  
Sub Saharan Africa ◽  
Species Extinction ◽  
Malaria Burden ◽  
Subjective Value ◽  
The World ◽  
Genetic Technologies ◽  
Sub Saharan

Each year, over 200 million people are infected with the malaria parasite, nearly half a million of whom succumb to the disease. Emerging genetic technologies could, in theory, eliminate the burden of malaria throughout the world by intentionally eradicating the mosquitoes that transmit the disease. In this paper, we offer an ethical examination of the intentional eradication of Anopheles gambiae, the main malaria vector of sub-Saharan Africa. In our evaluation, we focus on two main considerations: the benefit of alleviating the malaria burden, and the loss of value that would accompany the eradication of the species. We outline a typology of the different ways in which species are valued or could be valuable, then use that typology to appraise the value of the species in question. We argue that Anopheles gambiae has minor (and redundant) instrumental value, little final subjective value and no objective final value.

scholarly journals Evaluating the Evidence from Molecular Structure and Population Studies for Cross-Resistance to the Pyrethroids Used in Malaria Vector Control

2020 ◽  
Author(s):  
Catherine L. Moyes ◽  
Rosemary S. Lees ◽  
Cristina Yunta ◽  
Kyle J. Walker ◽  
Kay Hemmings ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Malaria Vector ◽  
Pyrethroid Resistance ◽  
Anopheles Funestus ◽  
Malaria Vectors ◽  
Cross Resistance ◽  
Malaria Vector Control ◽  
Insecticide Treated Nets ◽  
The Common ◽  
The Impact

Abstract The primary malaria control intervention in high burden countries is the deployment of long-lasting insecticide-treated nets (LLINs) treated with pyrethroids, alone or in combination with a second active ingredient or synergist. It is essential to understand whether the impact of pyrethroid resistance can be mitigated by switching between different pyrethroids or whether cross-resistance precludes this. Structural diversity within the pyrethroids could mean some compounds are better able to counteract the resistance mechanisms that have evolved in malaria vectors. Here we consider variation in vulnerability to the P450 enzymes that confer metabolic pyrethroid resistance in Anopheles gambiae s.l. and Anopheles funestus. We assess the relationships among pyrethroids in terms of their binding affinity to key P450s and the percent dep­letion by these P450s, in order to identify which pyrethroids diverge from the others. We then investigate whether these same pyrethroids also diverge from the others in terms of resistance in vector populations. We found that etofenprox, which lacks the common structural moiety of other pyrethroids, potentially diverges from the commonly deployed pyrethroids in terms of P450 binding affinity and resistance in malaria vector populations, but not depletion by the P450s tested. These results are supplemented by an analysis of resistance to the same pyrethroids in Aedes aegypti populations, which also found etofenprox diverges from the other pyrethroids in terms of resistance in wild populations. In addition, we found that bifenthrin, which also lacks the common structural moiety of most pyrethroids, diverges from the commonly deployed pyrethroids in terms of P450 binding affinity and depletion by P450s. However, resistance to bifenthrin in vector populations is largely untested. The prevalence of resistance to the pyrethroids α-cypermethrin, cyfluthrin, deltamethrin, λ-cyhalothrin, and permethrin was correlated across malaria vector populations and switching between these compounds as a tool to mitigate against pyrethroid resistance is not advised without strong evidence supporting a true difference in resistance.

Sign in / Sign up

Export Citation Format

Share Document