River blindness persists in Africa

MNGAZI, Tanzania — A man with clouded eyes sits on the ground next to a wattle and daube hut in the riverside village of Mngazi. His five children mill around and his wife tends a pot over a wooden fire. He used to be a corn farmer, but then his eyes started itching three years ago.

Now, he is totally blind and cannot work. He does not know what happened, nor is he the only villager whose vision began to disappear. He said he went to a witchdoctor, but it did not help.

The man’s blindness is not a result of magic, but a small worm that invaded his body. He is one of 37 million people worldwide, most of them in sub-Saharan Africa, suffering from onchocerciasis, commonly known as river blindness.

It is nearly impossible for many African villagers to avoid the disease, which is transmitted by black flies that breed in the clean, fast-moving water used for drinking, bathing and washing clothes. The flies are the vector for parasitic worms that are transmitted to humans through fly bites. The worms enter the body, nestling near bone protuberances, where they breed millions of offspring.

It is these small worms that cause the debilitating symptoms of the disease. The early stages produce incessant itching that makes it difficult to work and can cause people to lose sleep for years at a time. The latter stages can leave the victim blind.

The disease is curable — and the drugs are available for free — but it has still proven difficult to eradicate.

"Onchocerciasis is a forgotten disease," said Dr. Sungwa Ndagabewene, a medical officer in the Southern Highlands region of Tanzania whose one-story office is surrounded by flowers and roaming chickens. "It needs more attention and it is a disease which we can eliminate if we put more effort into it."

There is one effective medication available — ivermectin, manufactured by Merck — but it can be difficult to convince people to take it.

The drug does not kill the adult worms but reduces their breeding rate and kills off the belligerent offspring. When sufferers first take the drug, it can produce severe itching and swelling, as the baby worms inside the body die off.

The drug must be taken annually for the life of the adult worm, which is about 15 years. Further, everyone in the village must take the drug — with the exception of small children, the very ill and pregnant and nursing women — or else the worms will continue to breed and can reinfect the population.

Additionally, people frequently stop taking the drug once the symptoms of the disease subside, often after several years of treatment, said Tanzania’s minister of health and social welfare, David Mwakyusa.

Younger generations are often unaware of the disease in communities that have been receiving treatment for a long time, said Dr. Uche V. Amazigo, who runs a pan-African treatment program for the World Health Organization.

"They don ‘t even remember what onchocerciasis is, and that’s part of the problem," Amazigo said.

Over the last decade, Amazigo and her associates have developed a method to distribute the medicine by recruiting a network of thousands of local volunteers in each village.

The program treats nearly 54 million people annually in 15 countries. It has achieved a 30 percent reduction in the prevalence of infection, and a 55 percent reduction in itching. The rates of impaired vision and blindness have dropped by 35 percent.

The WHO tries to get national government to take over funding the programs once they are up and running, but that can be difficult.

"Onchocerciasis is not high up on the budget list compared to HIV/AIDS and tuberculosis," said Dr. Wade Asyukile Kabuka, an ophthalmologist who coordinates the project in the Ruvuma region of Tanzania.

Many villagers are also suspicious that the medicine is distributed for free. Health officials must combat a widespread belief that it is a part of a conspiracy to sterilize them.

One way Tanzanian health officials try to convince villagers to take the drugs is by telling them it will actually help their sex drive.

After taking the medicine, "people found they had increased libido, so they thought different," said Dr. Meshack Massi, a health official in Ulanga with a boisterous laugh. "The itching stops and you remember you have a partner in your bed."

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