The Useful Life of Bed-nets for Malaria Control in Tanzania: Attrition, Bio-efficacy, Chemistry, Durability and Insecticide Resistance, 2016

Long-Lasting Insecticidal Nets (LLINs) are the current first line choice in malaria vector control in sub-Saharan Africa (SSA), with most countries adopting universal coverage campaigns with free or subsidised nets. However, there is only limited knowledge from few countries of the effective life of LLINs under user conditions, an essential parameter for determining the operational and cost-effectiveness of this strategy. This study investigated LLIN effectiveness by measuring attrition, bio-efficacy, chemical content and physical degradation in Tanzania. A two-stage approach was used: Firstly, LLINs from recent net campaigns was evaluated retrospectively. The sampled households was then be provided with one of three leading LLIN products and followed up for three years in a prospective study to compare the performance of the LLIN brands in vivo. There was also developed a GIS-based network to understand potential spatial reasons for net loss and deterioration; to monitor insecticide resistance and to show malaria incidence data collected from local health centres and national surveys. A highly skilled multi-disciplinary team was brought together that supported the Tanzanian vector control both then and in the future through the training of two Tanzanian PhD students. This was the first team to conduct a geographically representative study of LLIN use and efficacy using WHO-recommended methodologies and large sample sizes determined by robust statistical methods with independent data quality assurance. The data collected will be of importance to policy makers and vector control specialists in both Tanzania and the SSA region to inform best practice for the maintenance of high and cost-effective coverage to maximize current gains in malaria control.