London School of Hygiene & Tropical Medicine

In a groundbreaking research trial conducted in Misungwi, rural Tanzania, researchers have reported the final-year findings of a study on long-lasting insecticidal nets (LLINs) containing new dual active ingredients. The World Health Organization (WHO) has recently recommended these nets in areas where malaria vectors have developed resistance to pyrethroids, the primary insecticide used in LLINs.

The trial, spanning three years, focused on evaluating the long-term effectiveness of four types of LLINs: standard pyrethroid LLINs (PY), chlorfenapyr–PY LLINs, pyriproxyfen–PY LLINs, and piperonyl butoxide (PBO)–PY LLINs. The research used a rigorous single-blind, cluster-randomized controlled trial methodology, with data collection conducted between July 14, 2021, and February 10, 2022.

Notably, the study showed that chlorfenapyr–PY LLINs displayed superior protective efficacy against malaria compared to standard PY LLINs over the 3-year lifespan of the LLINs. Despite challenges in achieving high coverage, the results emphasize the potential impact of innovative LLINs in combatting malaria in malaria-endemic regions.

The research team emphasized the importance of implementing appropriate LLIN replacement strategies or improve the durability of the nets to maintain adequate usage of these advanced nets and maximize their potential in the fight against malaria.

Dr Nancy Matowo a research fellow and public health Entomologist at LSHTM with a keen interest in operational research that will help countries to take sound decisions on vector control strategy that is based on scientific evidence, highlighted the significance of this groundbreaking research. Dr Jacklin Mosha, epidemiologist and co-lead researcher from NIMR, emphasised that these findings hold great promise for malaria-endemic countries in the fight against malaria.

She said: “This is a good news for Tanzania and Sub-Saharan Africa showing that chlorfenapyr–PY LLINs may be able to provide sustained protection over 3 years of used in area of moderate malaria transmission. However, the low bed net usage at the end of the trial raises urgent concerns and needs to be addressed urgently if we want to achieve the highest impact.

This is a collaborative project involving London School of Hygiene & Tropical Medicine, UK, the National Institute for Medical Research, Tanzania, University of Ottawa, Canada and Kilimanjaro Christian Medical University College in Tanzania.

This trial was made possible through funding from various organizations, including the Department for International Development, UK Medical Research Council, Wellcome Trust, Department of Health and Social Care, and the Bill & Melinda Gates Foundation via the Innovative Vector Control Consortium. The trial was registered with ClinicalTrials.gov (NCT03554616) and has now concluded.