Larva of a hookworm (Ancylostomatidae)(Photo by Agency-Animal-Picture/Getty Images)

Researchers at George Washington University hope to develop a vaccine to prevent an infection that is afflicting more than half a billion people around the world.

“This is one of the neglected tropical diseases that has the highest impact on health globally,” said David Diemert, an associate professor of microbiology, immunology and tropical medicine, who has been working with colleagues for more than a decade hoping to eradicate the effects of the hookworm parasite.

There’s just one problem: To effectively study the hookworm, researchers need healthy people in D.C. to volunteer to let the parasites burrow into their skin and live deep inside their bodies for several months.

“I tried my best to explain to people,” why they should volunteer, said Anna Markowitz, who has almost completed her master’s degree in public health at GW and stepped up to take part in the study. “But when you tell them that you’re in a clinical trial in which you inoculate yourself with parasites that will suck on your blood through your intestines, people aren’t too interested.”

It’s a common problem for scientists: They have questions. They have ideas – some of them brilliant. But when it comes time to test those ideas out in the real world, people just aren’t breaking down the doors to be their guinea pigs.

“I think most people in the community know that researchers greatly benefit from monetary donations,” said Jennifer Coughlin, an assistant professor in the department of psychiatry at the Johns Hopkins University School of Medicine who helps develop molecular imaging techniques to study brain disease. “But it is equally important that we not only study diseased participants but study healthy participants so that we have a comparative cohort.”

It can be tough to find those participants, even though they often are paid for their time.

At GW, their feasibility study – a step before a massive clinical trial – has gone through the usual rigorous internal and external evaluations. Still, here they are, ready to start with a second group of volunteers – except they don’t have 10 people signed up yet.

“Obviously, I’m kind of a weirdo to agree to do this,” Markowitz said.

Host parasites? Sure. Give blood samples? Why not? Bring in stool samples every week? No problem!

And for a lucky few: Endoscopy!

People agree for a variety of reasons: An interest in global health. Compassion. A commitment to medical research. A desire to help children living in rural poverty. A sick curiosity. Cash.

Markowitz’s friend, Patrick Prodey, a student at American University, was drawn to the weekly payments. “But on a philosophical level, I like the idea of challenging stigmatized things. When people would freak out – ‘Why do you have hookworms?!’ – I’d say, ‘Look, dude, I’m asymptomatic. This is helping solve an issue. And I’m getting paid for it.’”

He knows the basics: There are many people in developing countries who get infected — typically by stepping in something barefoot — and some suffering insidious but serious damage to their brains and growth over the years.

The medicine to treat the infection only gets to about half of those who need it in such places, and it has to be re-administered every year.

Diemert and another faculty member in GW’s School of Medicine and Health Sciences, Jeffrey Bethony, working with the Sabin Vaccine Institute, with funding from the National Institutes of Health, believe prevention is within reach.

“What is being argued here?” Prodey said, when people are shocked that he volunteered. “‘That’s yucky, that’s scary, that’s gross?’ That doesn’t make any sense.”

It does make a little bit of sense though. After all, the risks had been explained, the consent forms had been signed, and the volunteers sat for an hour with a gauze patch taped to their arms. Each patch carried 25 hookworm larvae, which quickly began burrowing their way into the people’s skin, headed for the intestines.

Prodey’s arm began to itch under the gauze, which he knew he shouldn’t touch, and he couldn’t help but think: Yuck.

Markowitz is pretty sure she just imagined the sensation that they were worming into her arm. But for days afterward she woke up scratching at the rash that lingered at the site.

Twenty-two of the larvae on her patch went in, and she named each of them – Elvis, Jemimah, and so on.

When doing some research on the Internet, she found a picture of a hookworm; someone had added cartoonish fangs and googly eyes. She found it reassuring — see, this is funny, not repulsive!

She and her friends didn’t have fevers, vomiting, diarrhea, any real gastrointestinal distress. Prodey found collecting the stool samples “laughably awkward” and the matching Cool-Whip-like containers and little lunch bags they were given for carrying them to the hospital ridiculous. “They were like, ‘It will be inconspicuous on the Metro!’”

One day, all three friends had their appointments at the same time, he said, and they walked along, swinging their identical bags: “We look like we’re all involved in some weird lunchbox cult.”

Markowitz liked the regular appointments; she gets dropped from her mom’s health-insurance plan next  month when she turns 26, so she thought it was a great benefit to constantly have her blood pressure and temperature and whatnot monitored. If she felt a little sick, rather than waiting forever to get an appointment, she sailed right in — and not only was it free, she was getting paid to be there.

Since they kept journals of any possible symptoms, she was very aware of her body and her health. All of that freaked Prodey out a little; he doesn’t like hospitals and overthinks things, so when they asked him if he was “extra flatulent” — a common side effect — he went into a spiral of wondering if he was and wishing he wasn’t thinking about it.

“Mostly I was digging it,” he said. “Getting $75 a week for showing up at an office once a week for 20 minutes max.”

Markowitz’s roommate would flash his “worm money,” a prepaid Visa card, at restaurants like a high roller to make her laugh. Markowitz earned almost $1,400, in part because she was selected at random for a capsule endoscopy. “That was totally my favorite part of it,” she said.

At the GW office where it was done, the staff was a little surprised: “This was the first time they’d ever seen someone so enthused for a procedure like this.”

After fasting for a day, then drinking something to flush out her system, she said, she went back to the doctor’s office in the morning “to swallow a pill with a camera in it. There was a big Walkman-like thing strapped around my abdomen. The pill was traveling through my intestines – about eight hours to go through the small intestine – and sending pictures back. I felt like the bionic woman with this flashing thing on me and a camera in my body. What a cool perk! I got to see pictures of my intestine!”

Needless to say, now she’s a zealot, trying to convince people to get in on this. “I felt good, knowing that I did what I could to help,” she said.

Prodey wants to try other clinical trials; he heard rumors about one testing how astronauts’ muscles atrophy during long space expeditions, and wondered if he could handle being part of a control group lying in bed for a year.

All things considered, yep.

“I don’t know where the line will be,” he said, but if he finds other studies, “I’m sure I’ll bump into it.”

At the end of the 12-week trial, they took the medicine known to wipe out the hookworms.

“We were all a little upset,” Markowitz said. “Our babies were gone. We had hosted them for a month – and suddenly, they were gone.”

[In Brazil, field trials to treat the world’s poor for hookworm.]