How many mosquito nets are needed to maintain universal coverage: an update.

BACKGROUND: Insecticide-treated nets (ITNs) have served as the cornerstone of malaria vector control in sub-Saharan Africa for the past two decades. Over 2.5 billion ITNs have been delivered since 2004 primarily through periodic mass distribution campaigns scheduled at approximately three-year intervals, aligning with the expected lifespan of nets. Recent work indicates that ITN retention times are less than two years in most countries, raising key questions for quantification approaches and delivery frequency for ITN distribution. This paper models several quantification approaches for five typical ITN distribution strategies, estimates the proportion of the population with access to an ITN, and presents recommended quantification approaches to meet global targets for ITN access and use. METHODS: A stock and flow model with annual timesteps was used to model ITN distribution and resulting ITN access for 2020-2035 under five scenarios in 40 countries: (1) three-year mass campaigns, (2) full-scale annual continuous distribution, (3) three-year mass campaigns plus continuous distribution in the years between campaigns, (4) three-year mass campaigns at different quantification approaches, (5) two-year mass campaigns at different quantification approaches. All scenarios included ITN distribution to pregnant women at antenatal clinics and infants at immunization visits. RESULTS: The current status quo of conducting mass campaigns every three years using a population/1.8 quantifier is insufficient to achieve or maintain targets of 80% population access to ITNs in most malaria-endemic countries, given most estimated retention times are less than three years. Tailored three- or two-year mass campaigns were less efficient than annual continuous distribution strategies in nearly all settings. For countries with at least 2.5 year median ITN retention times, full scale continuous distribution provided better ITN access while needing 20-23% fewer ITNs compared to current mass campaigns. CONCLUSION: Given variation in ITN retention times across countries, tailored quantification approaches for mass campaigns and continuous distribution strategies are warranted. Continuous distribution strategies are likely to offer more efficient ways to maintain ITN coverage, with fewer nets, where ITN retention times are at least two and a half years. National malaria programmes and their funding partners should work to increase the number of ITNs available to those vulnerable to malaria, while at the same time working to extend the useful life of these critical commodities.

Reported reasons for non-use of insecticide-treated nets in large national household surveys, 2009-2021.

BACKGROUND: Insecticide-treated nets (ITN) are the cornerstone of modern malaria vector control, with nearly 3 billion ITNs delivered to households in endemic areas since 2000. ITN access, i.e. availability within the household, based on the number of ITNs and number of household members, is a pre-requisite for ITN use. Factors determining ITN use are frequently examined in published literature, but to date, large household survey data on reasons given for non-use of nets have not been explored. METHODS: A total of 156 DHS, MIS, and MICS surveys conducted between 2003 and 2021 were reviewed for questions on reasons why nets were not used the previous night, identifying twenty-seven surveys. The percent of nets that were reported used the previous night was calculated for the 156 surveys, and frequencies and proportions of reasons for non-use were calculated within the twenty-seven surveys. Results were stratified by household supply of ITNs in three categories (not enough", "enough", and "more than enough") and by residence (urban/rural). RESULTS: The proportion of nets used the previous night averaged over 70% between 2003 and 2021, with no discernible change over this period. Reported reasons for why a net goes unused fell largely into three categories-nets that are extra/being saved for future use; the perception that there is little risk of malaria (particularly in dry season); and "other" responses. Net attributes such as colour, size, shape, and texture, and concerns related to chemicals were the least frequent reasons given. Reasons for non-use of nets varied by household net supply, and in some surveys by residence. In Senegal's continuous DHS, the proportion of nets used peaked during high transmission season, and the proportion of nets that went unused due to "no/few mosquitoes" peaked during the dry season. CONCLUSIONS: Unused nets were primarily those being saved for later use, or were not used due to perceived low risk of malaria. Classifying reasons for non-use into broader categories facilitates the design of appropriate social and behaviour change interventions to address the major underlying reasons for non-use, where this is feasible.

Examining the incentives and disincentives in the maintenance of Insecticide-Treated Nets among householders in Ghana.

OBJECTIVE: This study explored the factors that affect the incentive to care for Insecticide-Treated Nets (ITNs) among householders in the Shai-Osudoku District of Ghana. METHODS: The study employed a descriptive qualitative design. Four in-depth interviews (IDIs) and four focus group discussions (FGDs) were conducted to gather the data from 38 participants. A thematic technique was used to analyse the data. FINDINGS: Householders were aware of the importance and use of ITNs. The factors underlying the motivation of householders to care for ITNs included their need to stay healthy; inadequate funds to acquire new ITNs and pay for healthcare cost; and their knowledge of the use and efficacy of ITNs. It was also found that obtaining the nets at no cost; limited time available to mend the ITNs; and limited knowledge on how to mend the ITNs disincentivised householders from effectively caring for the nets. CONCLUSIONS: There is a need to rethink current ITN intervention programmes in ways that will improve the contents of public education messages and strengthen monitoring frameworks to ensure that householders take optimum care of their nets.

Householders' perception about sustaining the useful life of long-lasting insecticide-treated nets in Ghana.

BACKGROUND: This article explores the multifaceted perceptions among householders about the care, efficacy and disposal of long-lasting insecticide-treated nets (LLINs), especially those regarding the end of the useful life of LLINs, and their implications for malaria control. METHODS: We used a cross-sectional qualitative design. Data were gathered in the Shai-Osudoku District in the Greater Accra Region of Ghana using focus group discussions and in-depth interviews. A thematic analysis technique was applied to analyse the data. RESULTS: Four findings emerged. First, participants were familiar with LLINs and the issues concerning the end of their useful life. However, the application of this knowledge was deficient. Second, characteristics of effectiveness (e.g. torn beyond repair) other than the age of a net determined the end of the useful life of LLINs. Third, social desirability and other social practices had positive and negative influences on perceptions about LLIN use and the end of their useful life. Fourth, repurposing of LLINs signified the end of their useful life. CONCLUSIONS: Policies and strategies to position LLIN use as the leading resource for malaria control need to be innovative to accommodate the perceptions and practices of targeted households.