"Schistosomiasis is listed as a "neglected" tropical disease by the World Health Organization — one of those diseases that's been overlooked by modern medicine.
It mainly hits poor people in poor countries — and it hits a lot of them, up to 200 million a year. There are only a few drugs available to treat it. There are no designer drugs being cooked up in a lab in Europe for schistosomiasis. Doctoral students rarely pen their thesis on this disease.
But schistosomiasis can also be "neglected" by the very people it attacks. It can be a stealth disease. The infection starts slowly. A flatworm penetrates the skin of someone walking or working or swimming in contaminated water. The person doesn't feel sick. They pick up more parasites.
The host still feels fine, doesn't even know he or she is infected. The worms start having sex. They multiply. As the parasite population grows the person starts to feel sluggish, slightly off. The worm invasion may cause a fever or some abdominal pain but most people don't realize something's wrong. In parts of Africa and South East Asia where schistosomiasis is rampant, people can be infected for years before they start feeling sick.
The standard treatment is a drug called praziquantel — three doses spread out over the course of one day can cure most people of the worms that cause schistosomiasis.
But what if tea from a local plant worked just as well?
Pam Weathers, a biologist at Worcester Polytechnic Institute, has spent a lot of time studying how artimisinin and other derivatives of the Wormwood shrub attack malaria parasites in people. She figured Wormwood might also kill the worms that cause schistosomiasis.
So along with her colleagues she ran a trial on 800 people in the Maniema Province in the east of the Democratic Republic of Congo, all of whom had schistosomiasis. Half were treated with the drug, and half got Wormwood tea.
In a new study published this month, she reports that sweet wormwood tea can cure schistosomiasis faster and with fewer side effects than the most common drug treatment.
"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," she says with a laugh. "It means looking at fecal samples to see if the eggs are gone. I'm glad it wasn't in that lab but that's how it has to be detected."
The people who got the conventional drug and the people who drank the tea all were completely cleared of the parasites. But the group sipping the wormwood infusions got rid of the parasites faster and reported fewer side effects. "It [the tea] is much more benign on the patient," she says. The pharmaceutical treatment with praziquantel can cause headaches, nausea and fatigue.
One downside of the sweet wormwood tea is that despite the "sweet" in its name, it's actually quite bitter. Some people like it while others hate it.
Weathers falls in the hater group and was surprised to find that anyone thought it tastes good. "I'm like, you're kidding me because I can't stand it," she says.
But one of the benefits of using sweet wormwood is that the shrub grows readily in lots of the warm tropical places where schistosomiasis is a problem.
"The thought initially was that they we're going to try and let people grow the plant in their own gardens and then just make their own tea," Weathers says. This turned out to be not as easy as it might seem. The tea infusion had to be the right strength to be effective, and people had to be told to not store the prepared tea for more than a day or it would lose efficacy.
The new study from Weathers and her colleagues doesn't tackle those logistical issues. It simply set out to compare the wormwood tea treatment against the common drug therapy. And in that regard wormwood tea was a success.
"This is an important disease," says Sue Montgomery, who heads the parasitic disease branch of the Centers for Disease Control and Prevention. Montgomery wasn't involved with the wormwood tea study and says she doesn't want to comment directly on it. She notes that in other studies wormwood has showed promise in killing immature stages of the schistisoma parasite.
"But those are all in studies that have yet to be scaled up to the point where those drugs would be used in control programs," she says. Which is also true of Weathers wormwood tea study. It's still in the study stage and the tea is not yet being widely used to combat schistosomiasis.
The bigger problem with schistosomiasis is that just purging the parasites by pill or by tea won't lead to the elimination of the disease.
Schistosomiasis is spread in a cycle involving people and a particular species of freshwater snails.
"You have to have three things occurring in the same place to have transmission of schistosomiasis," Montgomery says. "You need people who are infected with the parasite. You need water sources that contain the appropriate snails that are intermediate hosts. And you have to have a situation where human waste is making its way into that water." Human feces and urine carry the parasite's eggs back out to the water source.
So just killing off all the parasites that are inside people doesn't do any good if they can get re-infected the next day by contaminated water.
"It's almost impossible to get rid of [schistosomiasis] just by treating repeatedly," Montgomery says. "What it really requires is improvements in water and sanitation."
And upgrading an entire community's water and waste systems is a lot harder than giving a patient a pill or some tea.
But tackling schistosomiasis, Montgomery says, is important. As more and more worms accumulate in a person, Montgomery says, the individual suffers a lack of energy and has trouble digesting food. As the number of worms swells and they lodge their eggs in various organs, many people end up with a fibrosis of the liver. And in a worst case scenario ...
"It influences the blood circulation, then it leads to enlarged blood vessels around the liver, which sometimes burst into your esophagus," Montgomery says. "And you can actually end up bleeding out from the esophagus because of the altered circulation caused by this chronic high level infection. So that's a really awful scary story, and it does not happen often but that's one of the causes of deaths associated with schistosomiasis."
The disease is so under-researched that there isn't even good data on exactly how many people are suffering or dying from schistosomiasis. The World Health Organization estimates that schistosomiasis kills between 25,000 and 200,000 people a year.
It's possible that some simple treatments like wormwood tea could help combat it. But the first challenge may be to stop neglecting this potentially fatal disease.
Jan. 7, 2019
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.