Insecticide-treated durable wall lining (ITWL): future prospects for control of malaria and other vector-borne diseases

Abstract

While long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the cornerstones of malaria vector control throughout sub-Saharan Africa, there is an urgent need for the development of novel insecticide delivery mechanisms to sustain and consolidate gains in disease reduction and to transition towards malaria elimination and eradication. Insecticide-treated durable wall lining (ITWL) may represent a new paradigm for malaria control as a potential complementary or alternate longer-lasting intervention to IRS. ITWL can be attached to inner house walls, remain efficacious over multiple years and overcome some of the operational constraints of first-line control strategies, specifically nightly behavioural compliance required of LLINs and re-current costs and user fatigue associated with IRS campaigns. Initial experimental hut trials of insecticide-treated plastic sheeting reported promising results, achieving high levels of vector mortality, deterrence and blood-feeding inhibition, particularly when combined with LLINs. Two generations of commercial ITWL have been manufactured to date containing either pyrethroid or non-pyrethroid formulations. While some Phase III trials of these products have demonstrated reductions in malaria incidence, further large-scale evidence is still required before operational implementation of ITWL can be considered either in a programmatic or more targeted community context. Qualitative studies of ITWL have identified aesthetic value and observable entomological efficacy as key determinants of household acceptability. However, concerns have been raised regarding installation feasibility and anticipated cost-effectiveness. This paper critically reviews ITWL as both a putative mechanism of house improvement or more conventional intervention and discusses its future prospects as a method for controlling malaria and other vector-borne diseases.

Use and disuse of malaria bed nets in an internally displaced persons camp in the Democratic Republic of the Congo: A mixed-methods study

“…Modifications to bed net design may make them more user-friendly within the small shelters of displaced populations. Alternatively, indoor residual spraying (IRS) could be used; however IRS can be operationally challenging and economically unsustainable [ 1 , 45 – 47 ]. Within Birambizo IDP camp, IRS was carried out when NGOs were permanently operating within the camp, however violent conflict has interrupted NGO efforts at maintaining IRS interventions.…”

“…One other possible vector control method that could be well suited to the IDP camp setting is the use of insecticide-treated tarpaulin for IDP shelters. A recent review [ 45 ] highlights evidence suggesting the effectiveness of insecticide-treated durable wall lining over multiple years, however phase III trials are still underway to provide evidence as to the operational implementation of this novel vector control method within displaced populations [ 48 – 50 ].…”

Protecting the peri-domestic environment: the challenge for eliminating residual malaria

“…The findings of this study suggest that IRS should include kitchens and verandas in addition to the inside walls of houses. Alternatively, novel control methods such as insecticide-treated durable wall linings 26 , spatial repellents [27][28][29] , insecticidal paints or screening to mosquito-proof verandas and kitchens could be evaluated.…”

Cost-effectiveness of Insecticide-treated wall liner and indoor residual spraying as additions to insecticide-treated bed nets to prevent malaria: findings from cluster randomized trials in Tanzania

“…[3] Subsequent research showed that the product was well accepted by users and could serve as a complement to LLINs. [3,[10][11][12] The ITWL offers several logistical advantages over IRS. The ITWL's expected multi-year e cacy avoids the complexity of repeated rounds of application in the same and successive years.…”

“…[7] In spite of this de ciency, a future ITWL could potentially be effective against malaria and other vector borne diseases. [10] However, the usefulness of an ITWL also depends on its cost and comparison with alternative approaches. Thus, this paper rst reports the economic cost of installing and removing ITWL in the Muheza trial.…”