The deadliest animal in the world isn’t the great white shark, or the grizzly bear, or even the moose. It is so small that you can easily wipe it away or even flatten it. Yet, by spreading pathogens, the mosquito kills more than a million people every year and sickens hundreds of millions more. To underline how dangerous they are, Bill Gates published his mosquito-related posts during what he called “Mosquito Week,” a kick-off on Shark Week. “Mosquitoes and the diseases they carry kill more people in one day than sharks in 100 years,” Gates wrote in an email to his blog subscribers.
The worst thing people get from mosquitoes is dengue fever, which kills 20,000 people a year and sickens another 400 million. But there is also Zika virus, West Nile virus, chikungunya and yellow fever. What many of us consider a nasty summer pest can actually be a deadly threat, especially in tropical climates.
What is Gates doing about it? Strangely enough, he supports a program that breeds Lake mosquitoes and release them in 11 countries, mainly in Southeast Asia and South America. These mosquitoes are infected with Wolbachia bacteria, which prevents them from transmitting the diseases that kill people. While the lab-grown mosquitoes reproduce with other mosquitoes, Wolbachia spreads through the mosquito population, making them decidedly less deadly. In a pilot program in Indonesia, releasing Wolbachia mosquitoes reduced the number of dengue infections by 77 percent. People may get as many itchy mosquito bites as before, but fewer of them die.
For obvious reasons, Gates writes, the idea of breeding mosquitoes and releasing them to bite unsuspecting humans didn’t sit well at first. But the results of the pilot were so impressive that now the biggest challenge is growing enough Wolbachia mosquitoes to supply all the places they want.
Using sugar to kill mosquitoes.
We all know mosquitoes love human blood and we have the bumpy, itchy bites to prove it. But it turns out that mosquitoes need sugar all their lives so they have enough energy to fly, while only mosquito mothers who forage for food for their larvae look for human blood.
Another initiative Gates mentions in his blog is one that uses a simple combination of sugar and insecticide to attract and then kill mosquitoes. The bait is behind a membrane that only mosquitoes can enter, so while it may attract other more beneficial insects like bees or butterflies, it won’t kill them. The bait is inexpensive to produce, small, lightweight and easy to nail to an exterior wall, Gates writes.
At the moment, the sugar baits are in the development stage. Research shows that, when combined with the mosquito netting and indoor insecticides already in common use, sugar bait can significantly reduce mosquito populations around homes, thus reducing the incidence of malaria by 30 percent in places where it is widespread. There were 241 million cases of malaria and 627,000 deaths in 2020, and that number continues to rise, so a 30 percent reduction could save hundreds of thousands of lives. Who knows? Maybe someday we’ll all have them hanging outside our homes.