DAVID GREENE, HOST:
What a difference a drug can make. Take the example of ivermectin's impact on river blindness. River blindness, as we first heard yesterday, is a parasitic infection that the World Health Organization says threatens more than 100 million people, mainly in Africa. For decades, efforts to control the disease were largely unsuccessful. All of that changed after the introduction of ivermectin in the late 1980s. But, as NPR's Jason Beaubien reports from Ghana, having an effective drug is just half the solution.
JASON BEAUBIEN, BYLINE: In the town of Beposo 2, Albert Tamanja Bidim is sitting under a tree in the center of the village. He's calling out the names of residents from a ledger to come and take their ivermectin tablets.
ALBERT TAMANJA BIDIM: (Foreign language spoken).
BEAUBIEN: As he shouts out the names, young children give a running commentary on whether that person is around; whether they're off working in their fields. Some of the kids run to look for the resident. Bidim doesn't get paid for distributing these pills in his village, but he takes the job very seriously.
BIDIM: (Foreign language spoken).
BEAUBIEN: "This job is so difficult," he says. Once a year, he has to go to every house in the village and track down everyone and make sure they take the tablets. Small children and pregnant women are exempt. Volunteers like Bidim are the foot soldiers in a global effort to wipe out river blindness. The parasitic infection is spread by black flies. These particular flies breed in rapidly-flowing rivers - thus the name river blindness. Blindness is actually a late stage of the debilitating disease. The infection, also known as onchocerciasis, causes intense itching as hundreds of thousands of larvae burrow under a person's skin.
NANA-KWADWO BIRITWUM: We have about 5 million Ghanaians at risk of onchocerciasis.
BEAUBIEN: Dr. Nana-Kwadwo Biritwum heads up Ghana's neglected tropical disease program. He describes attacking river blindness with ivermectin as sort of the public health equivalent of carpet bombing.
BIRITWUM: It's an annual treatment program where we go in with millions of tablets of ivermectin every year to treat every community. This is a public health program, and it's not targeted at individuals. It is targeted at villages - communities.
BEAUBIEN: The World Health Organization estimates 30 million people, primarily in equatorial Africa, are still infected with the parasites that cause the disease. Earlier efforts to get rid of river blindness focused on blasting the black flies with insecticide, but aerial spraying was expensive, spotty and ultimately abandoned. This new strategy using ivermectin instead attempts to break the transmission cycle in the host - in people. As good as this drug is, wiping out river blindness is still difficult for several reasons. First, trying to get everyone in a village or anywhere to take their medicine on cue is hard. Secondly, ivermectin doesn't actually kill the parasites - it only kills the offspring of the parasites, the larvae. And Doctor Biritwum, with the Ghana health ministry, says the adult parasites can live for up to 15 years.
BIRITWUM: So we need to wait until the adult worms naturally die out of the system.
BEAUBIEN: This means they have to keep treating infected villages over and over again for years to wipe out all the worms. Currently, Ghana is treating roughly 4 million people, or 15 percent of its population, with ivermectin. It's a big task, but it's been quite successful. Some hard-hit villages have gone from having 70 to 80 percent of adults testing positive for onchocerciasis 25 years ago, to just 2 to 3 percent testing positive today. In Latin America, mass distribution of ivermectin has allowed Mexico, Ecuador and Colombia to get rid of the disease entirely. The village chief in Beposo 2, Bondi Sanbark, says his village used to be full of blind men being led around by young boys.
BONDI SANBARK: (Through interpreter) So we should continue to distribute the drugs to them so that the disease will be gone forever.
BEAUBIEN: The chief says no one has gone blind in Beposo 2 for years. That's the power of ivermectin. River blindness is now on the verge of elimination in the Americas, and it's been sharply curtailed in parts of Africa. Ghana is now talking about trying to wipe out the disease by 2020. Biritwum at the ministry of health says before the arrival of this wonder drug, that never would've been possible. Jason Beaubien, NPR News.