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Background: Long-Lasting Insecticidal nets (LLINs) have contributed to the reduction of malaria in sub-Saharan Africa, including Tanzania. However, they rely on daily user behaviour and high coverage which is difficult to maintain. Also, insecticide resistance among malaria vector mosquitoes is contributing to reduced efficacy of control tools. To overcome these problems, we propose to evaluate a new tool for house modification, the dual active ingredient (dual AI) insecticide treated eave nets (ITENs) in combination with insecticide treated window screens (ITWS) for the control of malaria. Methods: Four hundred and fifty (450) households with intact walls, open eaves without screens or nets on the windows in Chalinze district will be eligible and recruited upon written informed consent. The households will be randomly allocated into two arms: one with ITENs and ITWS installed and the other without. Malaria parasite detection using a quantitative Polymerase Chain Reaction (qPCR) will be conducted shortly after the long rain (June/July, 2022) as the primary outcome and shortly after the short rain (January/February, 2022) as the secondary outcome. Other secondary outcomes include clinical malaria cases, and density of malaria vectors and nuisance after the short rain and long rain. In addition, surveys will be conducted in households with ITENs and ITWS to estimate the intervention’s cost during installation, adverse effects after one month of installation, and presence, fabric integrity and user acceptance after six and twelve months of installation. Bioefficacy and chemical content will be evaluated after 12 months of installation. Discussion: ITENs and ITWS have been shown in Kenya to reduce indoor mosquito density. However, it was not known if the indoor mosquito density reduction translated into reduction of malaria cases. Data from the study will measure the public health value of an additional intervention for malaria control in areas of mosquito insecticide resistance that does not require daily adherence. Trial registration: The study is registered on ClinicalTrials.gov.

Additional file 1: Appendix 1. Informed consent forms.

Background Long-lasting insecticidal nets (LLINs) have contributed to the reduction of malaria in sub-Saharan Africa, including Tanzania. However, they rely on daily user behaviour and high coverage which is difficult to maintain. Also, insecticide resistance among malaria vector mosquitoes is contributing to reduced efficacy of control tools. To overcome these problems, we propose to evaluate a new tool for house modification, the insecticide-treated eave nets (ITENs) in combination with insecticide-treated window screens (ITWS) incorporated with dual active ingredient (dual AI) for the control of malaria. Methods Four hundred and fifty (450) households with intact walls, open eaves without screens or nets on the windows in Chalinze district will be eligible and recruited upon written informed consent. The households will be randomly allocated into two arms: one with ITENs and ITWS installed and the other without. Malaria parasite detection using a quantitative polymerase chain reaction (qPCR) will be conducted shortly after the long rain (June/July, 2022) as the primary outcome and shortly after the short rain (January/February, 2022) as the secondary outcome. Other secondary outcomes include clinical malaria cases, and density of malaria vectors and nuisance after the short rain and long rain. In addition, surveys will be conducted in households with ITENs and ITWS to estimate the intervention’s cost during installation, adverse effects one month after installation, and presence, fabric integrity and user acceptance six and twelve months after installation. Bioefficacy and chemical content will be evaluated twelve months after installation. Discussion ITENs and ITWS have been shown in Kenya to reduce indoor mosquito density. However, it is not known if indoor mosquito density reduction translates into reduction of malaria cases. Data from the study will measure the potential public health value of an additional intervention for malaria control at the household level in areas of mosquito insecticide resistance that does not require daily adherence. Trial registration The study is registered on ClinicalTrials.gov.

Background As insecticide-treated nets (ITNs) wear out and are disposed, some household members are prioritized to use remaining ITNs. This study assessed how nets are allocated within households to individuals of different age categories as ITNs are lost or damaged and as new ITNs are obtained. The study also explored how ITN allocation affects ITN durability. Methods A cross-sectional household survey and ITN durability study was conducted among 2,875 households across Tanzania to determine the proportion of nets that remain protective (serviceable) 22 months after net distribution aiming for universal coverage. Allocation of study nets within houses, and re-allocation of ITNs when new universal replacement campaign (URC) nets arrived in study households in Musoma District, was also assessed. Results Some 57.0% (95% CI 53.9–60.1%) of households had sufficient ITNs for every household member, while 84.4% (95% CI 82.4–86.4%) of the population had access to an ITN within their household (assuming 1 net covers every 2 members). In households with sufficient nets, 77.5% of members slept under ITNs. In households without sufficient nets, pregnant women (54.6%), children 65 years (32.6%) sleeping under ITNs. Crowding ($$\ge$$ ≥ 3 people sleeping under nets) was twice as common among people residing in houses without sufficient nets for all age groups, apart from children $$\ge$$ ≥ 3 people slept under them (OR 0.50 (95% CI 0.40–0.63)), or if nets were used by school-age children (OR 0.72 (95% CI 0.56–0.93)), or if the net product was Olyset®. One month after the URC, only 23.6% (95% CI 16.7–30.6%) of the population had access to a URC ITN in Musoma district. Householders in Musoma district continued the use of old ITNs even with the arrival of new URC nets. Conclusion Users determined the useful life of ITNs and prioritized pregnant women and children

BackgroundAs the number of insecticide-treated nets (ITNs) in households (access) declines when nets wear out some household-members are prioritised to use the remaining ITNs. This study assessed how nets are allocated within households to individuals of different age categories as ITNs are lost or damaged and as new ITNs are obtained. The study also explored how ITN allocation affects ITN durability. MethodsA cross-sectional household survey and ITN durability study was conducted among 2,875 households across Tanzania to determine the proportion of nets that remain protective (serviceable) twenty-two months after net distribution aiming for universal coverage. Allocation of study nets within houses and re-allocation of ITNs when new Universal Replacement Campaign (URC) nets arrived in study households in Musoma District was also assessed.ResultsOnly 57.0% [95% CI: 53.9-60.1%] of households had enough ITNs for every household member (assuming one net covers every 2 members). In households with enough nets, 77.5% of members slept under ITNs. In households without enough nets, pregnant women (54.6%), children65 (32.6%) sleeping under ITNs. Crowding ( 3 people slept under nets) was twice as common among people residing in houses without enough nets for all age groups apart from children®. One month after the URC, only 23.6% [95%CI 16.7-30.6%] had access to an URC ITN in Musoma district. Householders in Musoma district continued the use of old ITNs even with the arrival of new URC nets.ConclusionUsers determined the useful life of ITNs and prioritized pregnant women and children

Almost 1.2 billion long-lasting insecticidal nets (LLINs) have been procured for malaria control. Institutional buyers often assume that World Health Organization (WHO) prequalified LLINs are functionally identical with a three-year lifespan. We measured the lifespans of three LLIN products, and calculated their cost-per-year of functional life, through a randomised double-blinded prospective evaluation among 3,420 study households in Tanzania using WHO-recommended methods. Primary outcome was LLIN functional survival (LLINs present in serviceable condition). Secondary outcomes were 1) bioefficacy and chemical content (residual insecticidal activity) and 2) protective efficacy for volunteers sleeping under LLINs (bite reduction and mosquitoes killed). LLIN median functional survival was significantly different: 2·0 years for Olyset, 2·5 years for PermaNet and 2·6 years for NetProtect. Functional survival was affected by accumulation of holes resulting in users discarding nets. Protective efficacy also significantly differed between products as they aged. The longer-lived nets were 20% cheaper than the shorter-lived product.

Background: Almost 1.2 billion long lasting insecticidal nets (LLINs) have been procured for malaria control. World Health Organization (WHO) prequalifies LLINs that remain adequately insecticidal three years after deployment. Institutional buyers often assume that prequalified LLINs are functionally identical with a three-year lifespan. We measured the lifespans of three LLIN products, and calculated their cost per year of functional life, to explore whether using such data for LLIN procurement could lead to more cost-effective product selection. Methods: A randomised double-blinded prospective evaluation of three pyrethroid LLIN products was conducted in 2013 to 2016 among 3,420 study households in Tanzania using WHO-recommended methods. Primary outcome was LLIN functional survival (LLINs present in serviceable condition). Secondary outcomes were 1) bioefficacy and chemical content (residual insecticidal activity) and 2) protective efficacy for volunteers sleeping under the LLINs (bite reduction and mosquitoes killed). Findings: LLIN median functional survival was significantly different: 2·0 years for Olyset, 2·5 years for PermaNet and 2·6 years for NetProtect. Functional survival was affected by accumulation of holes resulting in users discarding nets. Protective efficacy also significantly differed between products as they aged. Equivalent annual cost varied between $1·2 and $1·5 USD, assuming that each net was priced identically at $3. The longer-lived nets were 20% cheaper than the shorter-lived product. Interpretation: LLIN functional survival is less than three years, and differs substantially between products. These differences strongly influence LLIN cost-effectiveness, and cannot be ignored by LLIN buyers who care about value for money. Funding Statement: The research was made possible by the Research Council of Norway through the ABCDR Project no. 220757. Sarah Moore was funded by awards from IVCC and Notre Dame OPP1081737. Declaration of Interests: Sarah Moore, William Kisinza, Olivier Pigeon and Jason Moore conduct product evaluations for a number of vector control product manufacturers. The other authors declare that they have no competing interests. Ethics Approval Statement: Ethical approval was granted from ethical review committees at London School of Hygiene & Tropical Medicine (6333/A443), Ifakara Health Institute (IHI/IRB/AMM/ No: 07- 2014) and the Tanzanian National Institute for Medical Research (NIMR/HQ/R.8c/Vol. I/285).

Background The rate of physical deterioration of long-lasting insecticidal nets (LLINs) varies by household practices, net brand and environment. One way to sustain the protection provided by LLINs against malaria is through day-to-day care, and repairing holes as and when they occur. To ensure LLIN coverage is high between mass campaigns and, as international donor funds decrease, personal responsibility to maintain nets in good condition is becoming more important. This study aimed to understand local barriers and motivators to net care and repair in southern Tanzania in a community that receives free LLINs through a school-based distribution mechanism. Methods Qualitative research methods were applied in a rural and peri-urban village in Ruangwa district. Focus group discussions (FGDs) were conducted for five groups of 8–12 participants; (1) key informants, (2) young men (18–24 years old), (3) women (> 18 years) with children under the age of five, (4) older men (> 25 years), and (5) older women with or without children (> 25 years). In each village, five men, five women with or without children, and five women with children under the age of five were recruited for in-depth interviews (IDIs). After each IDI and FGD with women with young children, participants were guided through a participatory activity. The study also counted the number and size of holes in nets currently used by IDI participants to determine their physical degradation status. Results A general willingness to care and repair mosquito nets was observed in Ruangwa district for the love of a good night’s sleep free of mosquito bites or noises. Net care was preferred over repair, especially among women who were the primary caretakers. The main motivation to look after nets was protection against mosquito bites and malaria. Washing nets occurred as frequently as every other week in some households to ensure cleanliness, which prevented other dirt-related problems such as sneezing and headaches. Barriers to net care included care not being a priority in the day-to-day activities and lack of net retreatment kits. Net repair was reported to be a temporary measure and necessary as soon as a hole was identified. However, during the net assessment and participatory activity, it became clear that people did not actually repair smaller holes. Protection against mosquitoes, malaria and cost saving from replacing nets were identified as motivators for net repair. Barriers to net repair included it not being a priority to repair holes that could be tucked under the mattress and lack of knowledge on when to repair nets. Conclusion In Ruangwa, net care was defined as overall net maintenance, such as cleanliness, and not directly associated with the prevention of damage as reported in other studies. Net repair was reported as a temporary measure before the acquisition of a new net, hence not a priority in a busy household. Inconsistencies were observed between reported intentions to repair mosquito nets and current net condition. Targeted education through health facilities and community change agents are potential means to overcome barriers to net care and repair.