Reduce unused containers to stop mosquito breeding, say researchers

Stanford researchers working in rural Kenya have identified the most productive breeding habitats for mosquitoes that spread a range of untreatable viruses, revealing community strategies that could provide a solution.

The findings, published in PLOS Neglected Tropical Diseases, point to more effective and efficient health interventions spearheaded by women and children.

“Until everyone in the world has reliable access to safe piped water, low-tech community interventions that target unused water containers can lead to large reductions in human health risk from vector-borne diseases,” said lead author and Professor of Paediatrics in the Stanford Medical School Desiree LaBeaud.

The Aedes aegypti mosquito poses a major threat to global public health, transmitting a host of viruses such as dengue, chikungunya, Zika and yellow fever, for which there are no vaccines or therapies.

Countries on every continent except Antarctica have suffered a number of Aedes aegypti-spread virus outbreaks in recent years. These outbreaks have been underreported and infections often misdiagnosed in some African countries where public health efforts have long focused on night-time biting mosquitoes that transmit malaria.

The researchers found that residents in the study area had limited awareness of daytime-biting Aedes aegypti mosquitoes, and prioritised sleeping under bednets as a primary protection against mosquito-borne disease.

A new approach to source reduction

Because of a lack of piped water, most people in the region obtain water from rainfall and wells or boreholes. Many people also leave stored water uncovered in various containers. The researchers surveyed hundreds of residents and measured mosquito abundance in buckets, jerry cans and other water-holding containers — the most common breeding habitat for Aedes aegypti mosquitoes.

More than half of the mosquitoes found were in tyres, buckets and small containers with no immediate purpose, and nearly 40% of the mosquitoes they found were in buckets used for laundry. Although tyres accounted for less than 1% of all containers, they contained nearly a third of the mosquitoes found by researchers.

The findings suggest that reducing the number of unused containers lying around could be an efficient and effective means of mosquito control. Rather than try to cover or reduce the number of all water-holding containers or all containers of a certain type — a complex and difficult approach for community members to sustain — national and local health interventions should target the most likely mosquito-breeding habitats, such as laundry buckets and containers without a purpose, such as tyres and rubbish, according to the researchers.

According to the researchers, education and empowerment are key to the effort, as well as community events such as rubbish clean-ups to manage the accumulation of purposeless containers. The researchers emphasise that women and children are the most likely agents of change. Women, who are most likely to collect and store water for households, can use simple nets, such as torn bednets, to cover laundry buckets. Children, who are generally more willing to engage with new ideas and take up new behaviours, can collect unused containers or turn unused tyres into toys so they won’t collect water for mosquito breeding.

“It sounds simple, but targeting specific containers by purpose can have a huge impact,” said study lead author Jenna Forsyth, a postdoctoral research fellow at the Stanford Woods Institute for the Environment.

“It’s low cost, requires relatively little behaviour change and can be scaled up easily.”

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