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Victims are infected by tiny parasitic worms that are transmitted by the bite of a small black fly that breeds in fast-flowing rivers.
Standing on the bank of the Kitomi River in western Uganda, Dr. Frank Richards, Jr., the Director of the River Blindness Program at the Atlanta-based Carter Center, says, “I wouldn’t be surprised if you got 20 to 25 bites an hour at certain times of the day here. That’s the kind of biting rate that will easily sustain river blindness.”
Spreading through the body, the worms can cause total blindness and, more commonly a severe skin rash.
“And you get a tremendous amount of itching,” says Dr. Frank Walsh, a member of Uganda’s Onchocerciasis Elimination Program. “It’s difficult to describe this level of itching, because it reputedly has driven people to commit suicide.”
In Uganda, the government has now made a major commitment to fight this disease, working closely with The Carter Center.
Richards says, “Throughout Africa, the attempt now is to control the disease, to prevent blindness, to prevent skin disease. In Uganda the idea is to completely get rid of the parasite and therefore once and for all be through with the problem.”
To achieve that, Ugandan health authorities have adopted a two-part strategy. The first part is a mass treatment program with Mectizan.
“Mectizan is a medicine that is given free of charge by Merck and Company,” says Richards. “Billions of doses have been provided; this medicine is so safe: it doesn’t need refrigeration, it doesn’t need needles, and it doesn’t need highly trained people.”
Mectizan kills immature worms in the body, not only relieving itching but also improving vision and preventing blindness.
The second part of the strategy is vector control – attacking the black flies that transmit the disease.
Watching a government health team working with a flow-meter in the middle of the Tombe River in western Uganda, Richards explains, “We’re measuring the flow rates to determine the best way to dose an environmentally friendly larvicide called “Abate”, or temephos, to kill the aquatic stages of the black fly, which live on freshwater crabs.”
More than 90 percent of the small crabs in this river were once infected with developing stages of black flies. But after a year of monthly treatments with the larvicide, the crabs are clean.
Watching the team examine buckets of crabs that were trapped in baskets baited with raw meat, Richards explains, “A lot of crabs – but crabs that are clean of the black fly larvae and pupae, which indicate that the larvicide is doing what it’s supposed to do. It’s not hurting the crabs, but it is stopping the black fly.”
By eliminating black flies wherever they are found, and providing Mectizan treatments to populations at risk, Uganda is making real progress against a tormenting disease.
Richards says he believes Uganda is on the right track. “I think the outlook for river blindness is very bright, as we really begin to think about the opportunities we have to eliminate, completely eliminate, the parasite.”