Human body odour to lure malaria mosquitos

A solar-powered trap that uses chemicals found in body odourto lure and snare malaria mosquitos has cut the insect’s population on a Kenyan island by 70%.

Tobias Homan from the Wageningen University and Research Centre and colleagues from the Netherlands, Switzerland and Kenya installed specially designed mosquito traps on Rusinga Island in Lake Victoria. The traps, which run from power generated by solar panels and exude human smells, not only drastically cut the mosquito population, but also reduced malaria infection rates by 30%.

The environmentally friendly and effective way to keep the parasite at bay was unveiled in The Lancet.

While other mosquito-borne diseases such as the Zika virus wax and wane, malaria has never really gone away – particularly in Africa, where, each year, the parasite kills hundreds of thousands of people and costs the continent around $12 billion in healthcare and lost productivity.

Trapping and killing the Anopheles funestus mosquito, which carries malaria in the area, is one way to keep infection rates down. But finding a bait that the insects won’t develop resistance to is tricky – they tend to evolve immunity to synthetic baits quickly.

On top of this, odour traps need electricity to work. In most regions of Africa, there simply are no consistent power supplies.

So Homan and his colleagues built a solar-powered trap which used a mixture of five different chemicals produced by humans, as well as carbon dioxide, as bait. It’s unlikely the mosquitos would become immune to the bait’s lure, given they need to sniff out people to feed and survive.

During their three-year study, the team handed out mosquito nets and installed traps alongside houses on Rusinga Island, which has a population of around 25,000 people.

In the end, all of the island’s inhabitants took part in the trial. But as they rolled out the traps from 2012, the researchers found the proportion of people with malaria was 30% lower among those living in houses with a trap compared to people living in houses who were yet to have a trap installed.

The researchers admit their trap, on its own, is not the answer. But, they write, such traps “are likely to be complementary to other novel intervention strategies, such as intensified surveillance response or mass vaccination, for malaria control”.

And with a host of other technologies, the traps may contribute to the World Health Organisation’s aim to eradicate malaria by 2030.

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