River Blindness—Conquering a Terrible Scourge
BY AWAKE! CORRESPONDENT IN NIGERIA
THE scene was typical of many riverside villages in West Africa. A group of people sat on benches beneath a great tree that shaded them from the scorching sun. Five of them—four men and a woman—were totally and permanently blind.
“They didn’t know why they were becoming blind in the old village,” said the village chief, who was dressed in a flowing white robe. “Most of the old people there died blind. . . . They thought some devil was against them. They implored their fetishes to protect them. Their ancestors told them to give food to the fetishes. So they killed chickens and sheep as a sacrifice. But they still kept on going blind.”
In time, doctors came and explained that the blindness did not come from a supernatural source. It was the result of the disease onchocerciasis, or river blindness, so named because the tiny, biting flies that spread it lay their eggs in fast-flowing rivers.
Fortunately, river blindness is not as easy to catch as are other tropical diseases. It poses no threat to city dwellers nor to those making a short visit to an infected area. Blindness occurs only after repeated infections over many years.
Nevertheless, river blindness is a dreadful tropical disease, devastating the lives of millions. While it rages in some areas of the Middle East and Central and South America, the hardest hit are those who work and live near fly-infested rivers in equatorial Africa. In some villages virtually everyone has the disease. According to estimates by The Carter Center in Atlanta, Georgia, U.S.A., about 126 million people are at risk of infection. Another 18 million people carry in their bodies the parasitic worms that cause river blindness. The number of people already partly or totally robbed of their sight is estimated to be between one and two million.
Now, the centuries-old scourge is being subdued by the united efforts of WHO (World Health Organization) and other agencies, along with the governments of various countries. Against a backdrop of hostilities and hopelessness in much of Africa, this is a disease-control program that is working. The program is being hailed as “one of the twentieth century’s great medical and development triumphs.”
A Terrible Disease
River blindness is spread by several species of the female blackfly (genus Simulium). When an infected fly bites a human, it deposits the larvae of a parasitic worm (Onchocerca volvulus). Slowly, under the skin of infected people, the larvae mature and develop into worms up to two feet [60 cm] in length.
After they are fertilized, female worms each begin to produce tiny worms called microfilariae; they continue doing this for 8 to 12 years, producing millions of them. The microfilariae do not grow into adults unless they are picked up by a blackfly, undergo development inside the fly, and are passed back to a human. For the most part, these tiny, immature worms swarm through the skin and may eventually invade the eyes. As many as 200 million worms may seethe in one victim. So plentiful are they that diagnosis involves snipping tiny bits of skin for examination. Under a microscope, a skin sample may reveal hundreds of wriggling microworms.
These parasites torment their human victims. Over the years the skin of the infected person thickens and becomes scaly. Often patches of depigmentation appear. Victims develop what is vividly described as crocodile skin, lizard skin, or leopard skin. Itching is intense, reportedly driving some to suicide. If young worms invade the eyes, in time, vision deteriorates and the victim becomes totally blind.
In the poor, rural areas where the blackfly holds sway, blindness is a particularly difficult burden to bear. One reason is that many villagers superstitiously believe that blindness is a result of divine punishment and that blind people are useless in their communities. Another reason is that there are no governmental social benefits, making victims totally dependent on their families. Sata, a female victim of river blindness in Burkina Faso, said: “For a blind person, whether a man or woman, the suffering’s the same. If a young woman is blind and unmarried, she won’t get a husband. I got married before I became blind, but my husband died. My brother became blind when he was young and so couldn’t get a wife. We’re both supported by our families—for food, for everything. It’s terrible.”
In areas where river blindness is common, people often abandon their villages, forced by the fly and the disease to flee. Fertile land beside the water suffers neglect and becomes wasteland. This, in turn, contributes to poverty and famine.
Battling the Blackfly
International efforts to control river blindness in seven West African countries began in the early 1970’s. Armed with biodegradable larvicides, insecticides that kill larvae, fleets of helicopters, small planes, and trucks launched an offensive against the blackfly, the carrier of the disease. The object was to attack and kill the blackfly when it is most vulnerable—during its larval stage.
It was not necessary to poison entire rivers. Experts knew that female blackflies lay their eggs on water and that the eggs stick to branches and rocks just below the surface of river rapids. Only fast-flowing waters provide the emerging larvae with the abundant oxygen they need to survive. This meant that the breeding sites along rivers were limited and identifiable.
The purpose of spraying the breeding sites was not to eradicate blackflies entirely, an impossible task. But by reducing the numbers of flies, experts hoped that the chain of parasite transmission could be broken. Fewer flies would mean fewer new infections. In theory, if the flies could be suppressed until the existing parasites gradually died in people already infected, the time would come when there would be no parasites left. So, if a fly did bite a person, it would collect no parasites to pass to others.
The project was challenging. The flies breed in thousands of places difficult to reach. Also, since they can fly hundreds of miles, blackflies needed to be battled over a vast area. Moreover, exceptional vigilance would be required since even a month of neglect could result in the resurgence of fly populations, frustrating years of work.
Beginning in the 1970’s, aircraft selectively sprayed more than 12,000 miles [19,000 km] of remote waterways. As a result, the disease was cleared out of 80 percent of the infected areas in the countries that took part.
One or Two Tablets Once a Year
Then, beginning in 1987, another weapon was developed in the fight against river blindness. This time, instead of attacking the blackfly, the target was the parasites inside the human body. The weapon was a safe and effective drug named Mectizan (ivermectin), developed in the laboratories of an American pharmaceutical company.
To halt the progress of the disease, an infected person needs to take a single dose—one or two tablets—each year. Mectizan does not kill the adult parasitic worms in the body, but it does kill the microworms and inhibits the adult’s production of more microfilariae. This halts the progression of the disease in the victim and slows the transmission of the disease to others. The drug also works to reverse early lesions in the cornea of the eye and prevents others from worsening. However, it cannot repair old eye lesions, nor can it reverse blindness once it has occurred.
The problem, however, was distribution—getting the drug to the people in need. Multitudes living in remote and isolated villages can only be reached by foot. Bringing in a vehicle often requires clearing bush or even the construction of bridges. Sometimes civil strife, lack of funding, and local politics add to the difficulties of distribution. Yet, despite these obstacles, by early 1995 about 31 million Mectizan tablets had been distributed, mostly in Africa.
Over the past 20 years, the Onchocerciasis Control Programme has battled river blindness in 11 West African countries, an area three times the size of France. What have been the results? According to WHO figures, the combined use of larvicides and Mectizan has worked to protect more than 30 million people who were once threatened by this ancient and terrible scourge. More than 1.5 million people who were seriously infected by the parasite are now completely recovered. Moreover, the subduing of river blindness is also freeing about 60 million acres [25 million ha] of tillable land for resettlement and cultivation—enough land to feed about 17 million people annually.
The war is far from over. The African nations where river blindness has been fought contain less than half of the people threatened by the disease.
In recent years efforts to combat the disease have intensified. In just two years, from 1992 to 1994, the number of people treated with Mectizan more than doubled, from 5.4 to 11 million. By late 1994 some 32 countries in Africa, Latin America, and the Middle East had established Mectizan treatment programs, which may in time protect as many as 24 million people from blindness.
The Pan American Health Organization hopes to eliminate the disease as a public health threat in the Americas by the year 2002. In Africa, of course, the task is bigger. Nevertheless, the United Nations Children’s Fund observes: “It is already clear that for the generation now growing up blindness does not present the formidable future threat it once did, in a region in which loss of sight has long been a normal part of ageing.”
It warms the heart to learn of the efforts made to help people threatened by blindness. During his earthly ministry, Jesus Christ also showed loving concern for people by miraculously restoring sight to many who were blind. (Matthew 15:30, 31; 21:14) This showed on a small scale what will take place on earth under the Kingdom of God. Indeed, the time is coming when no one will be afflicted by blindness of any kind. God’s Word foretells: “At that time the eyes of the blind ones will be opened.”—Isaiah 35:5.
[Blurb on page 25]
“They used to blame the blindness on spirits. Now, they know it is the worms”
[Blurb on page 27]
One or two tablets a year may prevent river blindness