Out here on the endless swamps, a harsh truth has been passed down from generation to generation: There is no fear but the fear of hunger.
With that always weighing on his mind, Mwewa Ndefi gets up at dawn, just as the first orange rays of sun are beginning to spear through the papyrus reeds, and starts to unclump a mosquito net.
Nets like his are widely considered a magic bullet against malaria one of the cheapest and most effective ways to stop a disease that kills at least half a million Africans each year. But Mr. Ndefi and countless others are not using their mosquito nets as global health experts have intended.
Nobody in his hut, including his seven children, sleeps under a net at night. Instead, Mr. Ndefi has taken his family’s supply of anti-malaria nets and sewn them together into a gigantic sieve that he uses to drag the bottom of the swamp ponds, sweeping up all sorts of life: baby catfish, banded tilapia, tiny mouthbrooders, orange fish eggs, water bugs and the occasional green frog.
I know it’s not right, Mr. Ndefi said, but without these nets, we wouldn’t eat.
Across Africa, from the mud flats of Nigeria to the coral reefs off Mozambique, mosquito-net fishing is a growing problem, an unintended consequence of one of the biggest and most celebrated public health campaigns in recent years.
The nets have helped save millions of lives, but scientists worry about the collateral damage: Africa’s fish.
Part of the concern is the scale. Mosquito nets are now a billion-dollar industry, with hundreds of millions of insecticide-treated nets passed out in recent years, and many more on their way.
They arrive by the truckload in poor, waterside communities where people have been trying to scrape by with substandard fishing gear for as long as anyone can remember. All of a sudden, there are light, soft, surprisingly strong nets for free. Many people said it would be foolish not to use them for fishing.
The nets go straight out of the bag into the sea, said Isabel Marques da Silva, a marine biologist at Universidade Lúrio in Mozambique. That’s why the incidence for malaria here is so high. The people don’t use the mosquito nets for mosquitoes. They use them to fish.
But the unsparing mesh, with holes smaller than mosquitoes, traps much more life than traditional fishing nets do. Scientists say that could imperil already stressed fish populations, a critical food source for millions of the world’s poorest people.
Scientists are hardly the only ones alarmed. Fistfights are breaking out on the beaches of Madagascar between fishermen who fear that the nets will ruin their livelihoods, and those who say they will starve without them. Congolese officials have snatched and burned the nets, and in August, Uganda’s president, Yoweri Museveni, threatened to jail anyone fishing with a mosquito net.
We need a regulation to deal with these people, Mr. Museveni said.
Many of these insecticide-treated nets are dragged through the same lakes and rivers people drink from, raising concerns about toxins. One of the most common insecticides used by the mosquito net industry is permethrin, which the United States Environmental Protection Agency says is likely to be carcinogenic to humans when consumed orally. The E.P.A. also says permethrin is highly toxic to fish.
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Most scientists say the risks to people are minimal, because the dosages are relatively low and humans metabolize permethrin quickly. But with coldblooded animals, it’s a different story.
If you’re using freshly treated nets in a smallish stream or a bay in the lake, it’s quite likely you’re going to kill fish you don’t intend to kill, said Dan Strickman, a senior program officer for the Bill and Melinda Gates Foundation, which has invested heavily in malaria research and development. That’s definitely an environmental hazard.
The leading mosquito net manufacturers insist that their products are not dangerous. Still, many nets are labeled: Do not wash in a lake or a river.
Some labels go even further, warning people to pour any water used in washing a net into a hole in the ground, away from home, animals and wells.
When asked about this, Egon Weinmueller, a public health executive for BASF, a major netmaker, said, We want to avoid any form of contamination. He acknowledged that if it’s a small pond, say maybe 10 meters, it could be a problem.
Though experts say that the vast majority of mosquito nets are used exactly the way they were intended hung over beds the full extent of mosquito-net fishing is unknown.
No one is going to come forward in a survey and say, That thing you’re giving me, we’re not using it properly,’ said Seth Faison, a spokesman for the Global Fund to Fight AIDS, Tuberculosis and Malaria, which has financed the purchase of 450 million nets.
Yet Mr. Faison and several other public health officials maintained that mosquito-net fishing was anecdotal.
In regards to what we face, Mr. Faison said, it’s an infinitesimal problem, maybe 1 percent.
But that would still amount to millions of nets.
One of the few detailed studies on the issue showed that in several villages along Lake Tanganyika, an essential body of water shared by four East African nations, 87.2 percent of households used mosquito nets to fish. When that study was presented at a malaria conference last year, the reception, according to some of those in attendance, was decidedly cool.
People are very defensive about this topic, said Amy Lehman, an American physician and the founder of the Lake Tanganyika Floating Health Clinic, which conducted the study. The narrative has always been, Spend $10 on a net and save a life,’ and that’s a very compelling narrative.
But what if that net is distributed in a waterside, food-insecure area where maybe you won’t be affecting the malaria rate at all and you might actually be hurting the environment? she said. It’s a lose-lose. And that’s not a very neat story to tell.
Fabric of a Community
An insecticide-treated mosquito net, hung over a bed, is the front line in the battle against malaria. It’s also the perfect mosquito-killing machine. The gauzy mesh allows the carbon dioxide that people exhale to flow out, which attracts mosquitoes. But as they swarm in, their cuticles touch the insecticide on the net’s surface, poisoning their nervous systems and shutting down their microscopic hearts.
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Western governments and foundations donate the money. Big companies like BASF, Bayer and Sumitomo Chemical design the nets. They are manufactured at about $3 apiece, many in China and Vietnam, shipped in steel containers to Africa, trucked to villages by aid agencies, and handed out by local ministries of health, usually gratis. The World Health Organization says the nets are a primary reason malaria death rates in Africa have been cut in half since 2000.
But at the end of the line, in poor areas where little goes to waste, mosquito nets become many other things: soccer balls and chicken coops, bridal veils and funeral shrouds. Mosquito nets are literally part of the fabric of a community.
For many uses, a secondhand net, which has less insecticide on it, will do. But for fishing, it’s different.
New mosquito nets are the best, said David Owich, who fishes on Lake Victoria. No holes.
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