MICHEL MARTIN, HOST:
Switching gears now, one of the world's most common and stubborn tropical diseases is called schistosomiasis. The potentially fatal parasitic infection affects millions of people in poor countries with poor sanitation. But new research shows that the parasites can be killed off with a particular type of homegrown herbal tea. NPR's Jason Beaubien has this report.
JASON BEAUBIEN, BYLINE: In parts of Africa and Southeast Asia, schistosomiasis affects up to 200 million people annually. And, often, those people can be infected for years before they start feeling sick.
PAM WEATHERS: It's a disease that doesn't kill people right away, but it weakens them, makes them unable to have the energy to work or deal with life very well.
BEAUBIEN: That's Pam Weathers. She's a biologist at Worcester Polytechnic Institute in Massachusetts. Weathers spends a lot of time studying plants. She'd been looking at how sweet wormwood can be used to kill malaria parasites, and she figured wormwood might also work against the flatworms that cause schistosomiasis.
WEATHERS: You know what? The plant's name is wormwood. It was known, over the centuries, to treat worms.
BEAUBIEN: So Weathers and her colleagues set up a study to test wormwood against the one drug that's commonly used to treat schistosomiasis - praziquantel. They recruited 800 people with schistosomiasis in an eastern province of the Democratic Republic of the Congo. Half were treated with the drug praziquantel and half got sweet wormwood tea.
WEATHERS: They had to drink these tea infusions daily for seven days. And then, you would see what happened to their worm infestations, which is not a pretty thing to do, because it means looking at fecal samples to see if the eggs are gone. I'm glad I wasn't in that lab (laughter).
BEAUBIEN: But it worked. Actually, both methods worked. The researchers found that the worms had been cleared from all the patients, but the group sipping the tea got rid of the parasites faster and reported fewer side effects than those taking the standard drug. Another potential upside of using wormwood against schistosomiasis is that the bushy plant is already being cultivated in many parts of Africa to produce artemisinin for malaria medications.
WEATHERS: It grows quite readily around the world.
BEAUBIEN: She imagines people growing a few of these shrubs in their gardens and then a few times a year, making tea from the leaves to cleanse themselves of the parasites. The World Health Organization's approved treatment for schistosomiasis, however, remains praziquantel. The study Weathers co-authored on this appears in the journal Phytomedicine.
Dr. Sue Montgomery, who heads the Centers for Disease Control and Prevention's parasitic disease branch, says purging people of the parasites only deals with half of the schistosomiasis problem. The parasites also thrive in freshwater snails. In places where human waste contaminates local waterways, the parasite cycle between the people and the crustaceans. So treating someone with drugs or herbs doesn't do any good if they get reinfected the next day by contaminated water.
SUE MONTGOMERY: It's almost impossible to get rid of it just by treating, repeatedly. What it really requires is improvements in water and sanitation.
BEAUBIEN: Upgrading an entire community's water and waste systems, however, is a lot harder than giving a patient a pill or some tea. Jason Beaubien, NPR News.
[POST-BROADCAST CORRECTION: The audio version of this story incorrectly refers to snails as crustaceans. Snails are in fact part of the mollusk family, along with slugs, clams, mussels and octopuses.]