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.

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