Table 1.
Illustrative list of prospective tools/approaches for control of adult malaria vectors, outlining modes of action, whether the tool is ‘field ready’, the estimated to operational use and some of the remaining research and development challenges.
| CONTROL TOOL | COMPLEMENTARY MODE OF ACTION | FIELD-READY TECHNOLOGY | ESIMATED TIME TO USE | CHALLENGES | REFERENCES |
|---|---|---|---|---|---|
| Attractive Toxic Sugar Bait | YES: Targets both sexes of diverse mosquito species; repeated exposure across life time; independent of blood feeding or resting behavior; resistance breaking actives. | YES: Ongoing small- scale field trials; simple technology with available products. | 0–5 years | Short lifespan when used as sprays on vegetation; further work needed to evaluate in different ecological contexts and to optimize within integrated vector management strategies (IVM); non-target evaluation. | [33–42] |
| Swarm sprays | YES: Targets males and also pre- gravid females; independent of blood feeding or resting behavior; resistance breaking actives. | YES: Ongoing small- scale field trials; simple technology with available products. | 0–5 years | Large number of swarm targets; demonstrate impact across diverse species and ecosystems; needs optimization within IVM; cost evaluations and implementation strategies required (who sprays and who pays?). | [43–49] |
| Housing improvement | YES: Prevents house entry and protects users without LLINs; independent of insecticide resistance; potential for resistance breaking actives in Eave Tubes. | YES: Numerous available approaches and new technologies (like Eave Tubes) under large-scale field evaluation; existing field trials and meta analyses support impact; housing improvement is already happening across many disease affected countries. | 0–5 years | Further research required on appropriateness in different socioeconomic settings; need for cost- effectiveness evaluations and exploration of different implementation strategies. | [50–67] |
| Livestock targets | YES: Addresses problem of zoophilic vectors | YES: IRS of livestock structures can use existing technology; numerous topical insecticides and endectocides on market. | 0–5 years | Need for longer lasting endectocides to reduce treatment frequency; not all livestock are treatable or have defined housing structures; cost and effectiveness across different systems and socio-economic contexts. | [68–82] |
| Spatial repellents | YES: Potentially protects users before they go indoors and users without LLINs. | YES: Certain products already commercially available and used. | 0–5 years | Need for improved long lasting products; costs likely prohibitive in certain settings and require financial contribution from end- user (consumer products not covered by normal public health budgets); appropriate targeting and optimizing within IVM. | [83–87] |
| Next generation LLINs | NO: Resistance breaking but same limitations as conventional LLINs. | YES: Certain nets are available now and more are under development. | 0–5 years | Current next generation nets cost 2–3 times as much as standard LLINs; not clear that they completely restore efficacy and improve control in all locations; resistance can still evolve. | [90–93] |
| Next generation IRS | NO: Resistance breaking but same limitations as conventional IRS. | YES: Certain new products are available and more are under development. | 0–5 years | New IRS products cost more than existing IRS so either more money needs to be made available or fewer houses are sprayed; resistance can still evolve; many countries don’t use IRS. | [94–96] |
| Sterile Insect Technique via irradiation | YES: Targets all females and subsequent offspring; independent of blood feeding or resting behavior; independent of insecticide resistance. | YES/NO: Small-scale field trials with An. arabiensis but not yet applicable to other species. | 4–8 years | Fitness costs of irradiation; challenges of mass rearing and sorting of males; mating competition with wildtypes; dispersal constraints; mixed species complexes; public acceptance. | [10,11] |
| Topical repellents | YES: Independent of blood feeding or resting behavior. | YES/NO: Products do exist but little demonstrated protection against malaria infection (both field trials and metaanalysis). | 4–8 years | Need clearer efficacy data; costs; short duration products needing repeat application; user acceptance; potential for resistance | [97–99] |
| Endectocide for humans | YES: Targets mosquitoes whenever they feed on humans, including outdoor biters. | YES/NO: Some products readily available and undergoing fieldtesting but persistence issues possibly limit current utility. | 4–8 years | Need for longer lasting formulations; need better understanding of mode of action; need more efficacy data on lethal and sub-lethal effects; safety constraints; public acceptance; safety monitoring. | [78,81,100–102] |
| Transinfection with Wolbachia | YES: Population replacement or suppression approaches work irrespective of blood feeding or resting behavior, and insecticide resistance. | NO: Laboratory proof of principle only. | 8–10 years | Development of technology (stable transinfection in only one Anopheles species so far); works best with low density populations; potential fitness costs affecting dispersal and mating behaviors; effectiveness across environments; mass rearing; species complexes; environmental and ethical safety; regulation; public acceptance. | [10,11,19,20] |
| Population suppression strategies via genetic modification | YES: Targets all females and subsequent offspring; independent of blood feeding or resting behavior, and independent of insecticide resistance. | NO: Laboratory proof of principle only. | 8–10 years | Development of technology (there is no clear product as yet for malaria vectors); potential fitness costs; effectiveness across environments; challenges of mass rearing; mating competition with wildtypes; dispersal constraints; mixed species complexes; environmental and ethical safety; regulation; public acceptance. | [10–18] |
| Population replacement strategies using genetically modified mosquitoes and gene drive | YES: Many possible modes of action independent of blood feeding or resting behavior, and independent of insecticide resistance. | NO: Laboratory proof of principle only. | 8–10 years | Development of technology (there is no clear product as yet); potential fitness costs; effectiveness across environments; dispersal constraints; mixed species complexes; resistance evolution against transgene or gene drive; environmental and ethical safety; regulation; public acceptance. | [10–18] |
Tools highlighted in bold are those that have modes of action that complement current tools (i.e. target different mosquito behaviors or different segments of the mosquito population than conventional LLINs and IRS) and are sufficiently advanced that they could be implemented in the near term (i.e. either are, or are close to being, ‘field ready’).