Volunteers Who Say 'Bite Me' Are Helping To Win The War Vs. Mosquitoes

Apr 9, 2016
Originally published on April 11, 2016 6:31 pm

The headquarters for the U.S. military's longest war isn't at the Pentagon. It's here at the Walter Reed Army Institute of Research, a modest brick building in suburban Washington.

Like most military campaigns, this one requires volunteers. Their mission is to place a bare arm atop a mug of malaria-infected mosquitoes and sit still while the parasites enjoy a feast. The volunteers will get malaria, and this allows the military to see how humans respond to treatment.

"It's the Malaria Challenge model," said Debra Yourick, director of science education at the institute. "It's the only way you can actually test a vaccine or an anti-malarial as an effective therapy. It's a controlled malaria infection, one we know we can cure."

Mosquitoes have taste-tested 2,200 volunteers over the past three decades in the Malaria Challenge. The volunteers are bitten at least five times. Some have been bitten up to 1,000 times over several sessions.

All have survived and recovered — which shows the advances in combating diseases spread by mosquitoes.

Mosquitoes have been the world's deadliest animal for centuries, and the Zika virus is just the latest reminder of how much damage they can inflict.

But the news is actually very good on the mosquito front: For the first time in forever, humanity is getting the upper hand, and the U.S. military has been a key player in this marathon effort.

Just a decade ago, mosquitoes still claimed an estimated 1 million lives a year worldwide, the vast majority children in Africa who succumbed to malaria. But a number of breakthroughs, such as bed nets treated with insecticides, have pushed that number down dramatically, to around 500,000 last year, according to the World Health Organization.

George Washington Vs. The Mosquitoes

Like many parts of the world, the U.S. has long waged war against the mosquito.

During the Revolutionary War, Gen. George Washington sought to acquire tree bark from Peru that was believed to effectively treat malaria, a recurring threat to his troops.

In World War II, Gen. Douglas MacArthur said that for every division that was fighting, "I must count on a second division in hospital with malaria and a third division convalescing from this debilitating disease."

And it's no accident that Gen. Reed's name is on this research institute, which is linked to, but physically separate from, the more famous military hospital that also bears his name. The hospital is several miles away, also in suburban Washington.

Around 1900, Gen. Reed was among the first to link mosquitoes to diseases they transmit. That led a few years later to the first major eradication campaign, when the American military took over the Panama Canal project after yellow fever wiped out workers and bankrupted the French effort.

The Americans started dumping all the stagnant water, "and yellow fever infections in that area went down dramatically," said Yourick. "It was the first, 'Uh-oh, this is where it's coming from.' It's not coming from bad air or vomit or sweat. It wasn't that. It was the mosquito."

Today, the Walter Reed "insectary" is filled with buckets of malaria- and dengue-infested mosquitoes.

This research is a key part of the wider international effort that is finally succeeding in a major way and on a global scale. Yet many in this field, like Army Maj. Jeffrey Clark, say it's still too early to celebrate.

"I would caution in getting too optimistic, because I think it was in the late 1950s that we thought within four or five years, malaria would be wiped from the face of the earth," Clark says.

Clever Mosquitoes

In response to every breakthrough, mosquitoes have adapted with incredible speed. They become resistant to new sprays. Medicines to prevent and treat malaria become less effective over time. The mosquitoes are even outsmarting the bed nets by learning to dine at an earlier hour.

"Instead of biting in the middle of the night now, when people are sleeping, they're biting in the evening when they're sitting outside by the fire," Clark says. "So the bed nets are becoming less and less effective."

The institute has been working with pharmaceutical companies for years to develop a vaccine against malaria, which would be a huge breakthrough. But a successful vaccine remains elusive, and the fight against mosquitoes carries on.

"The parasite wants to survive just as much as we want to survive," says Clark. "So it's a never-ending battle."

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MICHEL MARTIN, HOST:

What is the deadliest animal on the planet? Would you guess that for centuries it's been the tiny annoying mosquito? Mosquitoes still kill about half a million people each year. The Zika virus is just the latest example of the damage they can inflict, yet there is good news on the mosquito front. And one of the surprising key players fighting them is the U.S. military. NPR's Greg Myre reports.

GREG MYRE, BYLINE: The headquarters for the U.S. military's longest war isn't at the Pentagon. It's the war against mosquitoes here at the Walter Reed Army Institute of Research.

This suburban Washington lab is part of a global effort making mosquitoes far less deadly. But it does require volunteers. And their mission is to place a bare arm on a mug of mosquitoes infected with malaria and sit still while the parasites enjoy a feast.

The volunteers will malaria, and this allows the military to see how humans respond to the illness.

DEBORAH YOURICK: And that's the only way you can actually test a vaccine or an anti-malarial.

MYRE: That's Deborah Yourick, director of science education at Walter Reed.

YOURICK: It's a controlled malaria infection, one we know we can cure.

MYRE: Mosquitoes have chomped on 2,200 people in this malaria challenge. Volunteers are bitten at least five times. Some have been bitten a thousand times over several sessions. They've all survived, which shows how far we've come. The Zika virus is the latest reminder that mosquitoes have been the deadliest animal for centuries, but there's actually very good news on the mosquito front. For the first time in forever, humanity is getting the upper hand. According to the World Health Organization, mosquito-related deaths have fallen from an estimated 1 million a decade ago to a half million today. How did that happen? Well, scientists keep inventing more effective sprays and medicines. But the biggest differences come from bed nets coded with insecticides. They've saved millions of lives, particularly among children in Africa who account for the vast majority of victims. Still, many in this field, like Army Maj. Jeffrey Clark, say it's far too early to celebrate.

JEFFREY CLARK: I would caution in getting too optimistic because I think it was the late 1950s that we thought for sure within four or five years malaria would be wiped from the face of the earth.

MYRE: The first big breakthrough came around 1900 when Gen. Walter Reed linked mosquitoes to the diseases they transmit. A few years later, the military took over the Panama Canal project after yellow fever wiped out workers and bankrupted the French effort. When the Americans drained all the stagnant water...

YOURICK: Yellow fever infections went down dramatically, went to nearly nothing.

MYRE: That's Deborah Yourick again.

YOURICK: It was the first - uh-oh, this is where it's coming from. It's not coming from what are called fomites, which is...

MYRE: Right, bad air...

YOURICK: ...You know, bad air or, you know, vomits or sweat, whatever - it wasn't that. It was the mosquito.

MYRE: Yet every time science advances, mosquitoes adapt. They become resistant to sprays and medicines. They're even outsmarting bed nets by dining at an earlier hour.

CLARK: So instead of biting in the middle of the night now when people are sleeping, they're biting in the evening when they're sitting outside by the fire. So the bed nets are becoming less and less effective.

MYRE: That's Maj. Clark again. The military has been working with pharmaceutical companies on a malaria vaccine for years. That would be a huge advance, but it remains elusive. So the fight is still taking place on several fronts - with sprays and pills and nets. The battle isn't over, but humanity finally seems to be winning. Greg Myre, NPR News, Washington. Transcript provided by NPR, Copyright NPR.