Larval source management, a method of controlling mosquito populations in areas where vector-borne disease is high, is effective and should be adopted more widely, a new paper argues.
A group of close to 50 researchers, led by Ifakara Health Institute, University of Glasgow and Liverpool School of Tropical Medicine, have published a review in Parasite & Vectors of existing evidence on larval source management (LSM) and made a set of recommendations for its wider implementation in Africa to control malaria and other diseases.
LSM refers to methods to control mosquitoes as larvae before they reach adulthood, and can include larviciding, habitat modification to make spaces less suitable for mosquitoes or the introduction of fish or other predators.
The team are concerned that LSM is being underused. One potential reason is that the World Health Organization (WHO) guidelines on malaria prevention recommend the use of LSM as a supplementary intervention to the core vector control methods of insecticide-treated nets and indoor residual spraying, arguing that its feasibility can be limited by larval habitats being numerous, transient, and difficult to find or treat. The paper suggests that financial restrictions may be leading donors to prioritise core interventions over other options.
The report argues that wider approaches are required to meet malaria elimination targets beyond those targeting adult mosquitoes. While recognising that there will be cases where LSM may not be effective, they show that the opportunities presented by new technologies and improved local knowledge indicate clearly that we could benefit greatly by expanding our use of LSM.
The team’s research draws on expert views, a review of countries that have eliminated local malaria transmission, and a mathematical modelling exercise to conclude that LSM is an effective way of reducing mosquito populations and the spread of disease.
They conclude that what is needed now is to update WHO guidelines on vector control to recognise LSM as a key intervention, which would open the door for increased funding for LSM and support for countries to implement strategies that they deem most appropriate to their local setting.
Dr Ellie Sherrard-Smith, Senior Lecturer in Epidemiology at LSTM and corresponding author on the paper, said: “LSM offers a way for communities to grow resilience against shifting geopolitical and climate challenges. There may be more uncertainty on how LSM efforts may deliver health impacts relative to standardised tools, though where LSM has been rigorous, outcomes can be beyond those expected from core interventions.”
Their seven recommendations go into further detail on how to implement LSM, including adopting strong community engagement and employment of local workforce, and the use of technological advances such as satellite imagery and drones to complement community-driven initiatives.
Professor Fredros Okumu, who works at both University of Glasgow and Ifakara Health Institiute and is lead author on the paper, said: “Africa must bring LSM to rural areas hit hard by malaria. To fix failing malaria control, we need to attack mosquitoes where they breed. In the waters and in homes. How to do this well depends on the place, but at the core, countries should consider having a well-organized force of paid local workers. They must also study mosquito habits in each area, and add tech to hit the worst breeding spots.”