Tea to fight malaria? Yes, but also no.
Brendan Borell has written a scathing attack on the WHO, published in Slate last week. Because of the basics of the story, I thought I knew what I was in for: someone is advocating the use of a cheap “natural” remedy instead of a well-understood synthetic drug. They’re anecdotally reporting extreme efficacy and no drawbacks. Meanwhile, medical authorities are tearing out their hair and imploring people to stick to the stuff that works.
That’s how stories about herbal medicine typically go in my world. But this isn’t quite one of them.
“Although the tea itself has traditionally been used in treatment, not prevention, in China, a randomized controlled trial on this farm showed that workers who drank it regularly reduced their risk of suffering from multiple episodes of malaria by one-third.”
Randomized controlled trial you say?
“Soon afterward, a researcher named Patrick Ogwang with the Ugandan Ministry of Health documented a decline of malaria incidence among almost 300 workers drinking the tea, and followed up with the randomized controlled trial demonstrating the tea’s effectiveness.”
Okay, I guess I did read that right. So I was initially quite persuaded by the article’s narrative. And the WHO’s objection isn’t that the tea doesn’t work—in essence their problem is that it does. But that’s not as backward as it sounds: because the tea contains the same active ingredient that we synthesize to make anti-malarial drugs, the concern is that widespread use of the tea will create a selective pressure that breeds a resistant parasite.
Now, I am Not A Doctor, but long-term exposure to subclinical doses of a drug does seem prone to creating resistance. Or as this informative paper puts it:
“There is no selection of resistance if the anti-malarial drug concentrations are high enough to kill all the sensitive and all the resistant parasites, or too low to kill either. Thus, there is a window of concentrations for any particular level of resistance that provide a selection opportunity.”
So if your concentration isn’t controlled, you run the risk of not only leaving resistant parasites alive, but also killing off their competition. And this wouldn’t only make the tea ineffective, it would render current drug programs ineffective at the same time. Tempting as it is to embrace a David vs. Goliath narrative, and compelling as the clinical results are, the WHO appears to have a solid medical rationale for their decision.
While it’s conceivable that there is a medical or biological refutation of the WHO’s position, Borell doen’t offer one. His arguments are primarily political and emotional. And understandably so. Though it’s not in the scope of this blog to comment on global politics, I certainly won’t say Borell is wrong in his general interpretation of prevailing attitudes regarding medicine and many other things on the African continent. But the malaria parasite doesn’t care. And if unregulated folk medicine produces a drug-resistant worm, where will we find a new treatment? Another shrub? Or will we start to care about the scientific consensus again at that point?
Within this controversy, there is a larger lesson about medicine in general: although we often talk about treatments in 
terms of what works and what doesn’t, that dichotomy rarely addresses the nuance of real-world situations. Does wormwood tea work? If the goal is to treat and prevent malaria now, yes. But if the goal is to eradicate the disease, or keep it under control in the long term, then doing everything that “works” is not going to work.
I should probably also point out that even alternative medicine websites promoting wormwood tea mention some pretty serious potential side effects—things like “organ damage” and “possibly death.” Of course, given the source, large grains of salt all around. Though they do link to an interesting case from the New England Journal of Medicine detailing the results of (accidentally) drinking wormwood essential oil. The effects include both tonic and clonic seizures as well as congestive heart failure and other organ damage. While risk analysis is understandably difficult, I’m not sure why the WHO would endorse the unproven, unregulated use of a substance like this even without the likely impact on existing drugs.
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