A New Weapon to Fight Mosquito-Borne Diseases: Tiny Fish
KAMPONG CHAM, Cambodia—In a backyard lush with mango and papaya trees, an addition to Touch Sophea’s family was stirring excitement: Several tadpole-size guppies were doing laps in a large barrel of water.
“They’re pretty to look at, with so many colors,” said the farmer. The 33-year-old gathered around the container with her three children, her husband, and her niece at their home in Kampong Cham province, about 80 miles from Cambodia’s capital, Phnom Penh.
Fish often have a spiritual significance in Asian cultures, and in Cambodia, they are seen as lucky. But these little swimmers, which at about half an inch long would be tough to spot if they weren’t so active, are not just pets, as Sophea’s children think of them.
They are part of a promising one-year trial testing a low-tech innovation against dengue and other diseases spread by mosquitoes. The nonprofit Malaria Consortium is nearing the end of an experiment in Cambodia that pits a low-tech innovation against a modern problem: As climate change has worsened, new regions are seeing more cases of dangerous illnesses spread by mosquitoes, such as dengue, which is responsible for an estimated 400 million infections annually, according to the World Health Organization. Though deaths from dengue are on the decline, the illness racks the body with symptoms including a mild fever, headaches, rashes, and sore muscles and joints—devastating livelihoods. In deadly cases, dengue causes severe bleeding and organ impairment. Infection numbers have risen, and in 2015 there were more than 3.2 million known dengue cases across the Americas, Southeast Asia, and Western Pacific, according to the World Health Organization. About 70 percent of infections occur in Asia, according to the journal Nature.Touch Sophea and her children gather around a barrel containing guppies. (Photo: Amy Fallon)
That high percentage is why scientists here are exploring simple solutions to some of medicine’s toughest problems—even as the search continues for cures to dengue and other mosquito-borne illnesses, such as Zika, malaria, and West Nile.
“There is an urgent need to find an effective low-cost and home-grown solution,” Jeffrey Hii, a senior vector-control specialist for Malaria Consortium, told TakePart.
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What can a guppy do? The aim of the pilot, which is funded by the U.K. and German governments, is for the fish to eat the mosquito larvae that are typically laid in natural water sources—which are abundant in the tropics—before the insects grow into adults and spread the disease. The guppies, which are indigenous to rice paddies and other of the region’s natural water sources, are kept in rain barrels that Cambodians have long relied on to hold water for cooking and cleaning. The barrels are situated near homes and attract the majority of mosquitoes that carry dengue nearer to humans.