Army Maj. Jittawadee Murphy peers into a paper bucket full of freshly hatched Anopheles stephanii mosquitoes. She needs to separate out the females — the only ones that bite — so they can be infected with malaria.
It turns out that sexing mosquitoes is easy.
"We kind of trick them," says Murphy, an entomologist. Female mosquitoes gravitate to any heat source, thinking it might be their next warm-blooded dinner wagon. So Murphy places the bucket next to a hot plate. "That side of the bucket is hot now," she says. "So all of the gals — the female mosquitoes — go and sit on that side of the bucket."
And once the females make their move, Murphy can suck them up through a straw.
These insects will be presented with some malaria-infected human blood to feast on. And then they'll be allowed to suck the blood of human volunteers — incidentally injecting them with Plasmodium falciparum, the deadliest kind of malaria.
It sounds bizarre, and even unethical. But in fact, over decades this kind of human experiment at the Walter Reed Army Institute of Research has produced an unparalleled outpouring of drugs and vaccines to prevent and treat malaria, one of the world's leading disease threats. It kills nearly 800,000 people every year — most of them infants, children and pregnant women in sub-Saharan Africa.
Human Experiments — And Success
Deadly as it potentially is, it's not unethical to infect human research subjects with falciparum malaria, because the infection is entirely curable — as long as it's treated within 36 hours after symptoms appear.
After 36 hours, the level of malaria parasites in the blood gets so high that "it becomes a race between how fast the parasites can be killed with medication versus how fast they're multiplying in the blood," says Col. Christian Ockenhouse, who is in charge of developing malaria vaccines at the Walter Reed Institute.
None of the 1,000 volunteers infected in Walter Reed experiments has died or suffered lasting damage from the experiment, Ockenhouse says.