A Research Agenda for Malaria Eradication: Vector Control

Alonso, Pedro L.; Besansky, N. J.; Burkot, Tom; Collins, Frank H.; Hemingway, Janet; James, Anthony A.; Lengeler, Christian; Lindsay, Steve W.; Liu, Q. Y.; Lobo, Neil F.; Mnzava, Abraham; Tanner, Marcel; Zwiebel, Laurence J.

doi:10.1371/journal.pmed.1000401

Cited by 224 publications

(153 citation statements)

References 26 publications

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“…Despite recent progress in combating the malaria parasite, nearly 200 million infections and around 500,000 deaths are caused by malaria annually, mostly in young children in sub-Saharan Africa [1, 2]. Even with new drugs and vaccines in the research pipeline [3], control of the Anopheles species that transmit human malaria remains the cornerstone of prevention and transmission reduction efforts [2, 4].…”

Section: Introductionmentioning

confidence: 99%

Disrupting Mosquito Reproduction and Parasite Development for Malaria Control

et al. 2016

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The control of mosquito populations with insecticide treated bed nets and indoor residual sprays remains the cornerstone of malaria reduction and elimination programs. In light of widespread insecticide resistance in mosquitoes, however, alternative strategies for reducing transmission by the mosquito vector are urgently needed, including the identification of safe compounds that affect vectorial capacity via mechanisms that differ from fast-acting insecticides. Here, we show that compounds targeting steroid hormone signaling disrupt multiple biological processes that are key to the ability of mosquitoes to transmit malaria. When an agonist of the steroid hormone 20-hydroxyecdysone (20E) is applied to Anopheles gambiae females, which are the dominant malaria mosquito vector in Sub Saharan Africa, it substantially shortens lifespan, prevents insemination and egg production, and significantly blocks Plasmodium falciparum development, three components that are crucial to malaria transmission. Modeling the impact of these effects on Anopheles population dynamics and Plasmodium transmission predicts that disrupting steroid hormone signaling using 20E agonists would affect malaria transmission to a similar extent as insecticides. Manipulating 20E pathways therefore provides a powerful new approach to tackle malaria transmission by the mosquito vector, particularly in areas affected by the spread of insecticide resistance.

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Section: Introductionmentioning

confidence: 99%

Disrupting Mosquito Reproduction and Parasite Development for Malaria Control

et al. 2016

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“…However, evolution of resistance to the active ingredients of these tools and little consideration of developing new complementary compounds targeting the ever changing behavioral traits of Afrotropical malaria vectors have greatly challenged efforts geared to bring malaria under control [2–4]. Nevertheless, vector control forms the integral platform of integrated malaria management aimed to reduce malaria reproduction rate to less than 1 [5, 6]. …”

Section: Introductionmentioning

confidence: 99%

Methanolic extract of Agerantum conyzoides exhibited toxicity and growth disruption activities against Anopheles gambiae sensu stricto and Anopheles arabiensis larvae

Muema

Njeru

Colombier

et al. 2016

BMC Complement Altern Med

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BackgroundVector control remains the mainstay to effective malaria management. The negative implications following persistent application of synthetic insecticides geared towards regulation of mosquito populations have necessitated prospection for ecofriendly effective chemistries. Plant-derived compounds have the potential to control malaria-transmitting mosquito populations. Previously, Agerantum conyzoides extracts have demonstrated toxicity effects on disease-transmitting mosquitoes. However, their efficacy in controlling Afrotropical malaria vectors remains unclear. Herein, the toxicity and growth disruption activities of crude methanolic leaf extract of A. conyzoides on Anopheles gambiae sensu stricto and An. arabiensis larvae were assessed. MethodsLate third (L3) instars of An. gambiae s.s and An. arabiensis larvae were challenged with increasing doses of crude methanolic extract of A. conyzoides. The larval mortality rates were recorded every 24 h and the LC50 values determined at their associated 95% confidence levels. ANOVA followed by Post-hoc Student-Newman-Keuls (SNK) test was used to compare results between treatment and control groups. Phytochemical profiling of the extract was performed using standard chemical procedures.ResultsTreatment of larvae with the methanolic extract depicted dose-dependent effects with highest mortality percentages of ≥ 69% observed when exposed with 250 ppm and 500 ppm for 48 h while growth disruption effects were induced by sublethal doses of between 50–100 ppm for both species. Relative to experimental controls, the extract significantly reduced larval survival in both mosquito species (ANOVA, F(8,126) = 43.16776, P < 0.001). The LC50 values of the extract against An. gambiae s.s ranged between 84.71–232.70 ppm (95% CI 81.17–239.20), while against An. arabiensis the values ranged between 133.46–406.35 ppm (95% CI 131.51–411.25). The development of the juvenile stages was arrested at pupal-larval intermediates and adult emergence. The presence of alkaloids, aglycone flavonoids, triterpenoids, tannins and coumarins can partly be associated with the observed effects.ConclusionThe extract displayed considerable larvicidal activity and inhibited emergence of adult mosquitoes relative to experimental controls, a phenomenon probably associated with induced developmental hormone imbalance. Optimization of the bioactive compounds could open pathways into vector control programmes for improved mosquito control and reduced malaria transmission rates.

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“…We analysed data using Review Manager 5 (RevMan 5) software (Review Manager 2014). We used fixed-effect meta-analysis to combine data when heterogeneity was absent.…”

Section: Methodsmentioning

confidence: 99%

Mosquito repellents for malaria prevention

Maia

Kliner

Richardson

et al. 2018

Cochrane Database of Systematic Reviews

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BackgroundMalaria is an important cause of illness and death across endemic regions. Considerable success against malaria has been achieved within the past decade mainly through long-lasting insecticide-treated nets (LLINs). However, elimination of the disease is proving difficult as current control methods do not protect against mosquitoes biting outdoors and when people are active. Repellents may provide a personal protection solution during these times.ObjectivesTo assess the impact of topical repellents, insecticide-treated clothing, and spatial repellents on malaria transmission.Search methodsWe searched the following databases up to 26 June 2017: the Cochrane Infectious Diseases Group Specialized Register; the Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE; Embase; US AFPMB; CAB Abstracts; and LILACS. We also searched trial registration platforms and conference proceedings; and contacted organizations and companies for ongoing and unpublished trials.Selection criteriaWe included randomized controlled trials (RCTs) and cluster-randomized controlled trials of topical repellents proven to repel mosquitoes; permethrin-treated clothing; and spatial repellents such as mosquito coils. We included trials that investigated the use of repellents with or without LLINs, referred to as insecticide-treated nets.Data collection and analysisTwo review authors independently reviewed trials for inclusion, extracted the data, and assessed the risk of bias. A third review author resolved any discrepancies. We analysed data by conducting meta-analysis and stratified by whether the trials had included LLINs. We combined results from cRCTs with individually RCTs by adjusting for clustering and presented results using forest plots. We used GRADE to assess the certainty of the evidence.Main resultsEight cRCTs and two RCTs met the inclusion criteria. Six trials investigated topical repellents, two trials investigated insecticide-treated clothing, and two trials investigated spatial repellents.Topical repellentsSix RCTS, five of them cluster-randomized, investigated topical repellents involving residents of malaria-endemic regions. Four trials used topical repellents in combination with nets, but two trials undertaken in displaced populations used topical repellents alone. It is unclear if topical repellents can prevent clinical malaria (RR 0.65, 95% CI 0.4 to 1.07, very low certainty evidence) or malaria infection (RR 0.84, 95% CI 0.64 to 1.12, low-certainty evidence) caused by P. falciparum. It is also unclear if there is any protection against clinical cases of P. vivax (RR 1.32, 95% CI 0.99 to 1.76, low-certainty evidence) or incidence of infections (RR 1.07, 95% CI 0.80 to 1.41, low-certainty evidence). Subgroup analysis of trials including insecticide-treated nets did not show a protective effect of topical repellents against malaria. Only two studies did not include insecticide-treated nets, and they measured different outcomes; one reported a protective effect against clinical case...

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A Research Agenda for Malaria Eradication: Vector Control

Abstract: The Malaria Eradication Research Agenda (malERA) Consultative Group on Vector Control outline the research needed to ensure vector control at every stage of malaria eradication.

Cited by 224 publications

References 26 publications

Disrupting Mosquito Reproduction and Parasite Development for Malaria Control

Disrupting Mosquito Reproduction and Parasite Development for Malaria Control

Methanolic extract of Agerantum conyzoides exhibited toxicity and growth disruption activities against Anopheles gambiae sensu stricto and Anopheles arabiensis larvae

Mosquito repellents for malaria prevention

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