Page updated 26 June 2016
Page Suggestions: Population Control, Signs of the end
Hidden Epidemic: Tapeworms Living Inside People's Brains
Parasitic worms leave millions of victims paralyzed, epileptic, or worse. So why isn’t anyone mobilizing to eradicate them?
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Breaking the Cycle
A great step forward came in the mid-1980s when praziquantel, the first drug able to kill tapeworm larvae in the brain, became widely available. But praziquantel proved too effective. It not only kills tapeworms but also triggers an immune reaction that causes brain swelling. “Paradoxically, we produce the disease we want to treat,” Nash says.
Over the years Nash and others refined the treatment by combining praziquantel with other drugs that tamp down the immune system. It is far from a perfect solution, though. Sometimes the immune system still overreacts, requiring years of care for seizures and other symptoms. And immune-suppressant drugs like steroids have side effects of their own.
The hunt for better drugs to fight neurocysticercosis is not an easy process. The best way to test potential medicines on tapeworms is to get living cysts out of infected pigs. Nash and his colleagues recently set up a lab in Peru, where infected pigs are abundant, to do just that.
Although finding a better cure is important, Nash is more interested in preventing tapeworms from getting into human brains in the first place by breaking their life cycle. A favored strategy is identifying people who have adult tapeworms in their bodies and giving them drugs to kill the parasites. It is also possible to vaccinate pigs so that they destroy tapeworm eggs as soon as they ingest them.
None of this is rocket science—which makes Nash all the more frustrated that so little is being done. “I see this as a disease that can be treated and prevented,” he says. But there are precious few resources available for treatment and little recognition of the problem. “All of this seems to be very feasible, but nobody wants to do anything about it.”