What is larval source management and how might it work?
Malaria is an infectious disease transmitted from person to person by mosquitoes, and the main interventions insecticide treated bed-nets and indoor residual spraying reduce malaria infection by targeting adult mosquitoes. Larval source management (LSM) also aims to reduce malaria but instead targets immature mosquitoes, which are found in standing water, before they develop into flying adults. This is done by permanently removing standing water, for example by draining or filling land; making temporary changes to mosquito habitats to disrupt breeding, for example by clearing drains to make the water flow; or by adding chemicals, biological larvicides, or natural predators to standing water to kill larvae.
What does the research show?
Where larval habitats are not too extensive and a sufficient proportion of these habitats can be targeted, LSM probably reduces the number of people that will develop malaria (moderate quality evidence), and probably reduces the proportion of the population infected with the malaria parasite at any one time (moderate quality evidence).
LSM was shown to be effective in Sri Lanka, India, the Philippines, Greece, Kenya, and Tanzania, where interventions included adding larvicide to abandoned mine pits, streams, irrigation ditches and rice paddies where mosquitos breed, and building dams, flushing streams, and removing water containers from around people’s homes.
In one study from The Gambia where mosquitos were breeding in large swamps and rice paddies, spraying swamps with larvicide using ground teams did not show any benefit.