Insecticide resistance and ITNs in India
Authors: Nafis Faizi, Jaspreet Kaur
Journal: The Lancet Global Health (2021)

The use of insecticide-treated bednets (ITNs) or long-lasting insecticidal nets (LLINs) are of major importance to countries planning to eliminate malaria such as India. In June, 2021, Steve Lindsay and colleagues1Lindsay SW Matthew BT Kleinschmidt I Threats to the effectiveness of insecticide-treated bednets for malaria control: thinking beyond insecticide resistance.Lancet Glob Health. 2021; (published online June 30.)https://doi.org/10.1016/S2214-109X(21)00216-3Summary Full Text Full Text PDF PubMed Scopus (12) Google Scholar reflected well on the threat to effectiveness of ITNs and the need to think beyond insecticide resistance. We agree with the authors that there is insufficient evidence to support that resistance has led to the failure of effective ITN benefits in malaria elimination. We also agree that ITN use should be measured through its access, use, resistance, and complementary benefits with insecticide residual spraying (IRS). Similar to sub-Saharan Africa, LLINs gave protection against malaria in India, despite insecticide resistance being reported in malaria vectors.2Chourasia MK Kamaraju R Kleinschmidt I et al.Impact of long-lasting insecticidal nets on prevalence of subclinical malaria among children in the presence of pyrethroid resistance in Anopheles culicifacies in central India.Int J Infect Dis. 2017; 57: 123-129Summary Full Text Full Text PDF PubMed Scopus (7) Google Scholar However, the major problem in India is the actual use of insecticide nets, which varies from 30–61%.3Sahu SS Keshaowar AV Thankachy S et al.Evaluation of bio-efficacy and durability of long-lasting insecticidal nets distributed by malaria elimination programme in eastern India.Malar J. 2020; 19: 186Crossref PubMed Scopus (2) Google Scholar There is need for continued funding and use of ITNs and LLINs; however, we wish to draw attention towards three additional concerns. First, the effect of resistance on the community must be acknowledged. The benefit of ITNs over traditional non-treated bednets is that high ITN coverage (80%) has incremental value that extends protection from mosquito bite to non-users.1Lindsay SW Matthew BT Kleinschmidt I Threats to the effectiveness of insecticide-treated bednets for malaria control: thinking beyond insecticide resistance.Lancet Glob Health. 2021; (published online June 30.)https://doi.org/10.1016/S2214-109X(21)00216-3Summary Full Text Full Text PDF PubMed Scopus (12) Google Scholar Such community protection measures are based on effectiveness and, in the absence of evidence, we do not know the effect of resistance on the community protection benefit of ITNs. Second, India's integrated vector management policy, which uses both ITNs and IRS, must adhere to the policy of using insecticides with different modes of action during codeployment.4WHOGlobal Technical Strategy for Malaria 2016–2030.https://www.who.int/publications/i/item/9789241564991Date: May 1, 2015Date accessed: July 8, 2021Google Scholar This concern relates to two outcome indicators for the Global Technical Strategy for Malaria 2016–2030: proportion of at-risk population who slept under ITNs in the previous night and proportion of at-risk population who were protected by IRS within 12 months.4WHOGlobal Technical Strategy for Malaria 2016–2030.https://www.who.int/publications/i/item/9789241564991Date: May 1, 2015Date accessed: July 8, 2021Google Scholar Third, evidence suggests that the association of increased net usage and mosquito mortality must be investigated further to ascertain the effect of resistance on the community protective behaviour of ITNs.5Kleinschmidt I Bradley J Knox TB et al.Implications of insecticide resistance for malaria vector control with long-lasting insecticidal nets: a WHO-coordinated, prospective, international, observational cohort study.Lancet Infect Dis. 2018; 18: 640-649Summary Full Text Full Text PDF PubMed Scopus (94) Google Scholar In conclusion, we propose that although ITNs and LLINs usage should be increased, addressing these concerns will ensure optimal benefits to continue in the elimination era. We declare no competing interests. Threats to the effectiveness of insecticide-treated bednets for malaria control: thinking beyond insecticide resistanceFrom 2004 to 2019, insecticide-treated bednets (ITNs) have been the most effective tool for reducing malaria morbidity and mortality in sub-Saharan Africa. Recently, however, the decline in malaria cases and deaths has stalled. Some suggest that this inertia is due to increasing resistance in malaria vectors to the pyrethroid insecticides used for treating ITNs. However, there is presently little evidence to reach this conclusion and we therefore recommend that a broader perspective to evaluate ITN effectiveness in terms of access to nets, use of nets, bioefficacy, and durability should be taken. Full-Text PDF Open Access