Abstract
BackgroundA novel, insecticide-treated, durable wall lining (ITWL), which mimics indoor residual spraying (IRS), has been developed to provide prolonged vector control when fixed to the inner walls of houses. PermaNet® ITWL is a polypropylene material containing non-pyrethroids (abamectin and fenpyroximate) which migrate gradually to the surface.MethodsAn experimental hut trial was conducted in an area of pyrethroid-resistant Anopheles gambiae s.l. and Anopheles funestus s.s. to compare the efficacy of non-pyrethroid ITWL, long-lasting insecticidal nets (LLIN) (Interceptor®), pyrethroid ITWL (ZeroVector®), and non-pyrethroid ITWL + LLIN.ResultsThe non-pyrethroid ITWL produced relatively low levels of mortality, between 40–50% for An. funestus and An. gambiae, across all treatments. Against An. funestus, the non-pyrethroid ITWL when used without LLIN produced 47% mortality but this level of mortality was not significantly different to that of the LLIN alone (29%, P = 0.306) or ITWL + LLIN (35%, P = 0.385). Mortality levels for An. gambiae were similar to An. funestus with non-pyrethroid ITWL, producing 43% mortality compared with 26% for the LLIN. Exiting rates from ITWL huts were similar to the control and highest when the LLIN was present. An attempt to restrict mosquito access by covering the eave gap with ITWL (one eave open vs four open) had no effect on numbers entering. The LLIN provided personal protection when added to the ITWL with only 30% blood-fed compared with 69 and 56% (P = 0.001) for ITWL alone. Cone bioassays on ITWL with 30 min exposure after the trial produced mortality of >90% using field An. gambiae.ConclusionsDespite high mortality in bioassays, the hut trial produced only limited mortality which was attributed to pyrethroid resistance against the pyrethroid ITWL and low efficacy in the non-pyrethroid ITWL. Hut ceilings were left uncovered and may have served as a potential untreated refuge. By analogy to IRS campaigns, which also do not routinely treat ceilings, high community coverage with ITWL may still reduce malaria transmission. Restriction of eave gaps by 75% proved an inadequate barrier to mosquito entry. The findings represent the first 2 months after installation and do not necessarily predict long-term efficacy.
Highlights
A novel, insecticide-treated, durable wall lining (ITWL), which mimics indoor residual spraying (IRS), has been developed to provide prolonged vector control when fixed to the inner walls of houses
In areas of hyper-endemic malaria transmission, even when universal coverage (UC) of long-lasting insecticidal nets (LLIN) is achieved and nets are in good condition, malaria prevalence can remain relatively high unless additional control tools are implemented [6]
The non-pyrethroid ITWL when used without LLIN produced 47% mortality but this was not significantly different to that of the LLIN (29%, P = 0.306), non-pyrethroid ITWL + LLIN (35%, P = 0.385), or pyrethroid ITWL (45%, P = 0.306)
Summary
A novel, insecticide-treated, durable wall lining (ITWL), which mimics indoor residual spraying (IRS), has been developed to provide prolonged vector control when fixed to the inner walls of houses. Most malaria-endemic countries have adopted policies to promote universal distribution of long-lasting insecticidal nets (LLINs) free of charge across all age groups, and an estimated 49% of the population in sub-Saharan Africa had access to at least one LLIN in their household in 2013 [1]. Resistance to pyrethroid insecticides used in all LLINs is widespread across vector populations and may reduce the level of community protection [2, 3]. Another challenge is maintaining effective year-round protection as during the hot dry seasons when transmission may still occur, some individuals are deterred from sleeping under nets [4]. The commodity cost of PMI-supported IRS campaigns with the organophosphate Actellic CS 300 (pirimiphos methyl CS) has been estimated to be more than four times the expense of using the pyrethroid Icon CS 10 (lambdacyhalothrin CS) to cover the same area [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
