Ending African River Blindness
Entomologist Vincent Resh has leveraged science and diplomacy to help bring an epidemic under control along 30,000 miles of West African rivers.
By helping to control the larvae of black flies along rivers in West Africa, Vincent Resh also helped eliminate a crippling disease plaguing 11 African countries. His work there has contributed to the well-being of 30 million people - helping to end an epidemic.
From among the stacks of papers covering his desk, Vincent Resh pulls a small memento from his years of work in West Africa. It's a simple metal statue of two human figures, each clutching one end of a long stick. The one to the rear is tall and slender; the one in front smaller, with child-like proportions. It looks like an ordinary piece of folk art until Resh, a professor of organisms and the environment, explains what it represents: a blind man being led by a child - two of the hundreds of thousands of victims of a disease known as African river blindness.
Decades ago, says Resh, the statue's scene was common in Ivory Coast, Ghana, Guinea-Bissau, and more than a dozen other countries in the tropical belt just south of the Sahara Desert. "In Africa, when I first began my work, I would sometimes see 20 adults, each being led like this," Resh says. "By the time they were 40 - sometimes even by the time they were 20 - they were blind."
In some areas, as many as three in ten adults lost their sight and were unable to support their families, while children were pulled out of school to guide elders from place to place. "People who were blind had a much shorter life expectancy, because their families couldn't afford to feed them," says Dr. David Molyneux, an expert in onchocerciasis treatment at the Liverpool School of Tropical Medicine and Hygiene. To compound the problem, healthcare workers and teachers were reluctant to work in infected rural areas for fear of contracting the disease. Reoccurring in one village after another, in country after country, the disease drained the medical, economic, and educational resources of the entire region.
Resh, a UC Berkeley professor of entomology, spent 15 years working on a massive international program to control river blindness in 11 West African countries. During that time, he traveled throughout the shelf of countries facing the Gulf of Guinea, from the verdant forests of Guinea-Bissau and Senegal to the west, to the ancient trading crossroads of Benin to the east; meeting people, sharing their food, hearing their stories, and growing ever more determined to halt the transmission of the disease.
African river blindness, also known as onchocerciasis, is caused by the nematode roundworm Onchocerca volvulus. The worm's larvae lurk within another regional scourge - the biting black flies that swarm over rivers and streams and draw blood from those who venture near in broad daylight. With every bite, infected flies inject a few larval worms into the wound. Once inside a human body, the parasites proliferate by the hundreds of thousands, causing unsightly skin discolorations, continual itching and lesions, and eventually obliterating sight. Flies that bite an infected person pick up larval worms, completing the cycle of transmission.
White colonists, however, insisted on re-creating the riverside towns they remembered from home. By removing longstanding cultural prohibitions, they made onchocerciasis more prevalent than ever before.
River blindness has historically plagued the fertile valleys of West Africa, but it was the arrival of Europeans that unleashed the full force of the disease upon the region's inhabitants. Traditional taboos had kept people from settling along riverbanks or visiting streams in broad daylight, when black flies are most active. White colonists, however, insisted on re-creating the riverside towns they remembered from home. By removing longstanding cultural prohibitions, they made onchocerciasis more prevalent than ever before. By the 1970s, several hundred thousand people were blinded by the disease. Perhaps more tragically for the region, the most fertile farmland - an area roughly the size of Michigan - was abandoned due to the risk of contracting the disease.
The Onchocerciasis Control Programme (OCP) in West Africa was begun in 1974 by a coalition of the World Health Organization, the World Bank, the United Nations, and 20 donor countries and agencies. The $500 million campaign had three primary components.
- One contingent treated infected residents with doses of the anti-parasitic drug ivermectin, which averted blindness and removed the human reservoir of the disease.
- A second contingent aimed to break the cycle of transmission from human to fly by using widespread, long-term insecticide applications to control black fly populations.
- The third contingent monitored river organisms to ensure that the biodiversity of the rivers - a major source of food - remained intact.
An expert in aquatic insects with a strong record of working on sprawling, multinational river projects, Resh served as an international science advisor for the program. He teamed up with local colleagues and science experts in participating countries to plan and implement the spraying and environmental sampling. He got the job done in classic Resh-style - a foundation of sound science administered with get-your- feet-wet-and-hands-dirty diplomacy. An easygoing man with a smile never far from his broad face, it's easy to see why he made such strong connections with scientists, drivers, translators, and guides from a dozen different cultures and countries.
While growing up in New York, Resh never dreamed he might become a regular traveler to Africa. For vacations, his parents took the family to locales such as New Jersey and Pennsylvania. Once on his own, he filled his passport pages quickly, researching and teaching in Belize, Guatemala, and then working on a large project in France, studying the ecology of the Rhone River.
In Africa, Resh's primary goal was to kill the black fly larvae maturing in river waters. He supervised the spraying of insecticides on 30,000 miles of rivers every week to interrupt transmission of the disease. It was a narrow path to walk. "Most of the populations living along the riverbanks also used the water for drinking," says Albert Akpoboua, a Togan who worked closely with Resh on both vector control and monitoring programs on behalf of the World Health Organization. "We had to make sure the insecticide dosages were safe for people." At the same time, they had to ensure that insects, fish, and other creatures would recolonize the waterways. "The biggest fear is that we would get rid of the disease and suddenly lose the protein source - the fish," Resh says. "Ecological integrity was the key." Meanwhile, the threat of insecticide resistance continued to loom large; efforts to eliminate malaria in Africa by spraying with the insecticide DDT had failed by 1969 because mosquitoes had developed immunity to the chemical.
To address all three needs - disease control, vector control, and wildlife preservation - the OCP rotated among seven different larvicides. During the wet season, when rivers ran high, the scientists applied harsher organophosphates, pyrethroids, and carbamate insecticides; during low flows, they applied the more benign, biodegradable agent Bti, which is widely used in environmentally sensitive habitats in California. "This avoided too much selective pressure from one larvicide on the target organisms, and reduced the chance of resistance," Akpoboua says.
To keep his finger on the pulse of aquatic life, Resh directed a vast aquatic biomonitoring operation in treated rivers. He helped train teams of local workers to sample the prevalence of fish and benthic macroinvertebrates, such as mayfly nymphs, shrimp, shellfish, and other species. Feedback from the monitoring helped modulate the spraying schedule, with drops in certain species or a resurgence of the biting flies prompting shifts in insecticide selection.
The project kept Resh on the road and in the rivers for weeks at a time to visit sampling sites, organize personnel, and train local contacts. Of course, being on the water exposed Resh to both biting flies and infection. "We would spread grease, like Vaseline, over ourselves. And if you missed any place, the flies would find you and go straight in through your sleeves. It was just awful." Even so, he says, his suffering was minor compared to those of residents, who might sustain 10,000 black fly bites a year, each bite threatening to infect or to aggravate existing disease.
"We would spread grease like Vaseline over ourselves. And if you missed anyplace the flies would find you, go straight in through your sleeves. It was just awful."
Resh witnessed many of the devastating and unexpected effects of the disease. On a visit to one village, he began chatting with a half-dozen children who had collected on the riverbank. "I said to my translator, these kids are very, very friendly. And he replied, 'they're not kids, they're adults.' The parasite load on their bodies was so high that their growth was stunted." A photo of the scene shows that the tallest man stands well below the shoulder of Resh's sturdy five-foot-eight frame.
Resh's journeys through the region gave him an unforgettable view of West Africa's rich quilt of cultures, customs, and landscapes. He was invited to a wedding in Burkina Faso where the main course was camel, the preferred beverage millet beer, and the drinking lasted for three days. He visited such marvels as an elaborate replica of St. Peter's Cathedral in Ivory Coast, accompanied by both his Muslim driver and guide, each fearful of divine retribution. Resh witnessed an uglier side of life in Africa, too, when he was caught in the midst of a revolution wherein he was "surrounded by 15-year-old Angolan soldiers twirling Kalashnikovs on their fingers." He often flew with pilots who were afraid to land because of gunfire.
"I came to know a fascinating group of people on a very intimate basis because we shared everything. It became clear to me early on that we were all deeply committed to the importance of this project and were willing to make personal sacrifices," Resh says. Resh made a similar impact on his African colleagues. "Dr. Resh was very meticulous with his work and all of his problem solving approaches," says Akpoboua, who worked and traveled with Resh on OCP business from 1995 onward. "He would always have time to listen to the technicians and advise them, and he was a very friendly and personable man with a sense of humor. You could get to like him very easily."
"I look on the work I did in Africa as the defining point in my life. You get caught in these movements where you see the potential to do good, so three million kids don't go blind."
Resh has paid a steep price for his African travels. In the 1990s he acquired a lung parasite that made him so ill for 3 years that he nearly retired. "I'd be sick from the last time I was there, and I'd be going back," he says. The malaria Resh caught there still haunts him with occasional bouts of fever and chills. Despite these drawbacks, Resh's experiences with the program have moved him deeply. "The work I did in Africa was the defining point in my life. You get caught in these movements where you see the potential to do good, so 3 million kids don't go blind," he says. "A day doesn't go by that I don't think about these things."
As planned, in 2002 Resh turned the program over to the Africans he had helped to train. When it was time to say farewell, he walked away content. His efforts reopened to farming 60 million acres of land once abandoned to the disease, and protected the sight of an estimated 30 million people at risk for blindness. "You control the disease, you grow food for 17 million more people, and you still have the fish," he says.
By all accounts, the OCP has made a tremendous difference in the everyday lives of rural residents. "In Burkina Faso, I see the change in the situation from what it was before the program and now," Akpoboua says. "All of the clinical manifestations of the disease used to be very common around the Volta River: young children leading the blind, the whole area without schools or health facilities. Today, schools have been built in these areas, they have health clinics, new houses are being constructed. The changes are very visible."
"You control the disease, you grow food for 17 million more people, and you still have the fish,"
The OCP was so successful that in 1996, the Programme for Onchocerciasis Control, a campaign to distribute ivermectin, was launched in the 19 remaining African countries infested with the disease.
Today, life-sized versions of Resh's small river-blindness statue stand at the headquarters of the World Health Organization, the World Bank, and Merck & Co. (the pharmaceutical company that donated the ivermectin used to treat the disease), as symbols of the program's phenomenal success. For those who toil to rid the globe of malaria, tuberculosis, HIV, and infant diarrhea, the statue is a reminder of the human suffering they aspire to relieve.
Reflecting on his work, Resh says he was lucky to have been part of such an important environmental program. "It was a very humanizing experience. When I was really sick with lung problems, I wondered whether what I had done was worth it. But you learn that there are things that are bigger than yourself - that 30 million is better than one."