Fighting Malaria With a ‘Trojan Cow’

Here’s a glimpse into a possible future, if Brazilian entomologist Agenor Mafra-Neto gets his way:

A mosquito carrying the parasite that causes malaria buzzes around a cow. This particular cow smells different to it than other cows do. Mosquitoes only consume human blood, but the scent coming from this cow signals “boy,” not “bovine”—the cow has received an artificial lactic acid treatment that fools mosquitoes into thinking they’re biting humans. So the insect lands on it to feed. Once satiated, it flies off, apparently unaffected by the experience—as is the cow, because cows don’t get malaria.

But the bug’s bulging abdomen belies that it will soon die, poisoned by a second compound in the cow’s blood, and taking with it any chance of its spreading malaria to a human.

This “trojan cow” approach could soon be implemented on the ground in malaria hot spots, if testing goes well and it's not too expensive. Malaria is a debilitating disease that killed about 626,000 people in 2012, most of them African children, and sickened an estimated 207 million more worldwide. Medicine to treat it is expensive. A vaccine has shown promise but is years away from widespread distribution. The insecticide sprayed on mosquito nets that donor groups hand out in African villages doesn't last forever. So the faux–lactic acid treatment producing the human-esque aroma, combined with a widespread deworming medicine that happens to be fatal to mosquitoes, is a new approach that disrupts transmission.

“Trojan cows would use a clever form of misdirection,” said Martin Edlund, CEO of Malaria No More, a nonprofit organization dedicated to ending death from malaria in Africa. “Every time infected mosquitoes feed on cows instead of humans, it lessens the chance we’ll be infected with malaria.”

The “attract” element of the artifical lactic acid treatment, called Abate, was the original pursuit at ISCA Technology, the pest-management firm in Riverside, California, of which Mafra-Neto is CEO. But the native Brazilian and his team, he said, thought to “turn it into an ‘attract and kill’ system.” So they started “looking at the different ways of killing mosquitoes.”

They soon discovered something that seemed like an incredible fit—the leading bovine deworming medication that kills mosquitoes and is widely in use throughout Africa. The fatal effect lasts for at least a month. ISCA would like to work with deworming campaigns to deliver a one-two punch.

“Mosquito-transmitted diseases really affect the way that Africa can develop,” said Mafra-Neto, who has traveled throughout the continent. “Being able to break down this transmission cycle is important because it’s a way you can change the world very quickly. As an entomologist and as a chemical ecologist, I wanted to figure out a way.”

ISCA is working to refine the Abate treatment, perfecting the formulation and ensuring that it will continue to be effective on cows for at least a month. Though Abate was slated for testing this year, the Ebola outbreak has forced the company to put those plans on hold. Mafra-Neto hopes that the Abate solution will be inexpensive and long-lasting enough to be used widely, both alone and in tandem with other initiatives.

“Today, we’re experiencing a new golden age of discovery and innovation aimed at beating this disease,” said Edlund. “That means rethinking every approach and assumption. Trojan cows might be one of the tools that helps to tip the balance.”