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The Control of Onchocerciasis
AMERICAN JOURNAL OF OPHTHALMOLOGY® FRANK W. NEWELL, Publisher and Editor-in-Chief Suite 1415, 435 North Michigan Ave., Chicago, Illinois 60611 Thomas M. Aaberg, Atlanta Douglas R. Anderson, Miami Jules Baum, Boston William M. Bourne, Rochester Ronald M. Burde, New York Fred Ederer, Bethesda Frederick T. Fraunfelder, Portland Frederick A. [akobiec, Boston Michael A. Kass, St. Louis Steven G. Kramer, San Francisco Irving H. Leopold, Irvine
EDITORIAL BOARD
Robert Machemer, Durham A. Edward Maumenee, Baltimore Irene H. Maumenee, Baltimore Nancy M. Newman, San Francisco Don H. Nicholson, Miami Edward W. D. Norton, Miami Arnall Patz, Baltimore Deborah Pavan-Langston, Boston Allen M. Putterman, Chicago Dennis Robertson, Rochester
Merlyn M. Rodrigues, Baltimore Stephen J. Ryan, Los Angeles Jerry A. Shields, Philadelphia M. Bruce Shields, Durham David Shoch, Chicago Ronald E. Smith, Los Angeles Bruce E. Spivey, San Francisco Bradley R. Straatsma, Los Angeles H. Stanley Thompson, Iowa City E. Michael Van Buskirk, Portland Gunter K. von Noorden, Houston
Published monthly by the OPHTHALMIC PUBLISHING COMPANY Suite 1415, 435 North Michigan Avenue, Chicago, Illinois 60611 Directors A. Edward Maumenee, President David Shoch, Vice President Frank W. Newell, Secretary and Treasurer
Edward W. D. Norton Bruce E. Spivey Bradley R. Straatsma
EDITORIAL
The Control of Onchocerciasis Frank C. Winter River blindness is on the decline in a large area of West Africa thanks to an outstanding example of international and interdisciplinary teamwork. For generations Onchocerca volvulus has been the cause of immense human misery and blindness in equatorial Africa and parts of Latin America. Currently the World Health Organization estimates that about 85.5 million people are at risk for onchocerciasis, 17.5 million are infected, and 340,000 are blind. But even these huge numbers represent a 13% decline in the numbers of infected over a ten-year period. In West Africa it is estimated that 1.25 million people are no longer infected and three million children have been born free of the risk of blindness. 1.2 Two entirely different but equally remarkable events account for the reduction in the incidence of infestation and blindness from this disease. The first is the World Health Organiza-
tion Onchocerciasis Control Program, and the second is the introduction of the drug ivermectin. The tragedy of river blindness is intensified for the ophthalmologist by the frustration of not being able to prevent or treat the disease by ophthalmic means. The blindness is an ocular manifestation of a systemic infestation in which hundreds of thousands, even millions of filariae infiltrate the body, with particular effect on the skin and the eyes. The ocular results are sclerosing keratitis, chorioretinitis, and optic atrophy. The control of river blindness is the result of a remarkable international alliance in which entomologists, epidemiologists, chemists, medical administrators, pharmacologists, and international financial managers play equal or greater roles than ophthalmologists. Although onchocerciasis, as a helminth infestation, had been known for a century, its 84
Vol. 108, No. 1
Editorial
ocular manifestation was only described in the 1930s and 1940s. A turning point came in 1950 when John Wilson, Director of the Royal Commonwealth Society for the Blind, hearing stories of African villages where 50% or more of the adult population was blind, visited Northern Ghana to see for himself. He and his wife were deeply touched by the misery they found. They stayed with B. Broughton Waddy, the District Medical Officer, at Tamale. Waddy recounts that John Wilson said it would be impossible to mount an effective public campaign against a disease with an unpronounceable name. "Why not call it river blindness," Wilson said, and thus was born the name by which the public knows the condition today. Waddy and other British and French officials believed that in the absence of a safe medication for the disease, the best hope of control lay with a massive, integrated spraying campaign to control the insect vector, a swarming irritating fly known as Simulium damnosum. Breeding in running waters and feeding on nearby villagers, this vector produced a highly geographic pattern of the disease. The complexity and cost of such a spraying campaign made it an impossibility until a second turning point in 1972. At that time Robert S. MacNamara, President of the World Bank, visited Ouagadougou in what is now Burkina Faso. He was impressed when the authorities told him onchocerciasis was their worst problem. Waddy's unpublished journal (Life and Death in West Africa) again relates:
lvermectin is a synthetic derivative of Streptomyces avermitilis. It was developed by Merck & Co. as an antihelminthic for livestock and later found to be safe and effective in humans as a microfilaricide in Onchocerca volvulus infection. The mechanism of action is not clearly established, but the clinical effect is the rapid elimination of microfilariae from the skin after a single oral dose of the drug. This is followed by a more gradual disappearance of microfilariae from the cornea and anterior chamber. There are minimal systemic or ocular side effects, and a single dose is effective for six to 18 months. The adult worm is not affected, and since the female lives for 12 to 15 years, a single annual dose of ivermectin taken for 15 years should free the victim of the effects of infection. During this time a fly feeding on a treated individual should have a much reduced chance of ingesting a microfilaria, thus breaking the chain of transmission. The health workers are delighted to have this new drug available to combine with the spraying campaign in a more rapid extension of the control program to new areas. There are many questions still to be answered and the road ahead appears at least as long and hard as that already past, but there are experts now who believe that the final conquest of onchocerciasis is a matter of time and hard work. Finally, let us not fail to see that this enormously complex and expensive international effort is pointing us back to a great joy of medicine, the relief of suffering without thought of return.
He listened to what the French entomologist and I had to say. As we walked back to his aeroplane with him he said "Obviously I can't promise you anything off the cuff, but I shall do my best for you." That visit was the final act needed to open the international treasure chests and produce the very large sums needed for onchocerciasis control.
The program started in 1974 and is expected to last into the 1990s. The teams combating onchocerciasis were tremendously encouraged two years ago when Merck & Co. announced that it would make ivermectin available free of charge, as much as might be needed to complete the battle against river blindness.
85
Reprint requests to Frank C. Winter, M.D., Christian Eye Ministry, P.O. Box 9774, San Diego, CA 92109.
References 1. Epidemiology of Onchocerciasis. Report of WHO Expert Committee, Technical Report Series No. 597. Geneva, World Health Organization, 1976. 2. WHO Expert Committee on Onchocerciasis. Third Report. World Health Organization Technical Report Series No. 752. Geneva, World Health Organization, 1987.
EDITORIAL BOARD
Robert Machemer, Durham A. Edward Maumenee, Baltimore Irene H. Maumenee, Baltimore Nancy M. Newman, San Francisco Don H. Nicholson, Miami Edward W. D. Norton, Miami Arnall Patz, Baltimore Deborah Pavan-Langston, Boston Allen M. Putterman, Chicago Dennis Robertson, Rochester
Merlyn M. Rodrigues, Baltimore Stephen J. Ryan, Los Angeles Jerry A. Shields, Philadelphia M. Bruce Shields, Durham David Shoch, Chicago Ronald E. Smith, Los Angeles Bruce E. Spivey, San Francisco Bradley R. Straatsma, Los Angeles H. Stanley Thompson, Iowa City E. Michael Van Buskirk, Portland Gunter K. von Noorden, Houston
Published monthly by the OPHTHALMIC PUBLISHING COMPANY Suite 1415, 435 North Michigan Avenue, Chicago, Illinois 60611 Directors A. Edward Maumenee, President David Shoch, Vice President Frank W. Newell, Secretary and Treasurer
Edward W. D. Norton Bruce E. Spivey Bradley R. Straatsma
EDITORIAL
The Control of Onchocerciasis Frank C. Winter River blindness is on the decline in a large area of West Africa thanks to an outstanding example of international and interdisciplinary teamwork. For generations Onchocerca volvulus has been the cause of immense human misery and blindness in equatorial Africa and parts of Latin America. Currently the World Health Organization estimates that about 85.5 million people are at risk for onchocerciasis, 17.5 million are infected, and 340,000 are blind. But even these huge numbers represent a 13% decline in the numbers of infected over a ten-year period. In West Africa it is estimated that 1.25 million people are no longer infected and three million children have been born free of the risk of blindness. 1.2 Two entirely different but equally remarkable events account for the reduction in the incidence of infestation and blindness from this disease. The first is the World Health Organiza-
tion Onchocerciasis Control Program, and the second is the introduction of the drug ivermectin. The tragedy of river blindness is intensified for the ophthalmologist by the frustration of not being able to prevent or treat the disease by ophthalmic means. The blindness is an ocular manifestation of a systemic infestation in which hundreds of thousands, even millions of filariae infiltrate the body, with particular effect on the skin and the eyes. The ocular results are sclerosing keratitis, chorioretinitis, and optic atrophy. The control of river blindness is the result of a remarkable international alliance in which entomologists, epidemiologists, chemists, medical administrators, pharmacologists, and international financial managers play equal or greater roles than ophthalmologists. Although onchocerciasis, as a helminth infestation, had been known for a century, its 84
Vol. 108, No. 1
Editorial
ocular manifestation was only described in the 1930s and 1940s. A turning point came in 1950 when John Wilson, Director of the Royal Commonwealth Society for the Blind, hearing stories of African villages where 50% or more of the adult population was blind, visited Northern Ghana to see for himself. He and his wife were deeply touched by the misery they found. They stayed with B. Broughton Waddy, the District Medical Officer, at Tamale. Waddy recounts that John Wilson said it would be impossible to mount an effective public campaign against a disease with an unpronounceable name. "Why not call it river blindness," Wilson said, and thus was born the name by which the public knows the condition today. Waddy and other British and French officials believed that in the absence of a safe medication for the disease, the best hope of control lay with a massive, integrated spraying campaign to control the insect vector, a swarming irritating fly known as Simulium damnosum. Breeding in running waters and feeding on nearby villagers, this vector produced a highly geographic pattern of the disease. The complexity and cost of such a spraying campaign made it an impossibility until a second turning point in 1972. At that time Robert S. MacNamara, President of the World Bank, visited Ouagadougou in what is now Burkina Faso. He was impressed when the authorities told him onchocerciasis was their worst problem. Waddy's unpublished journal (Life and Death in West Africa) again relates:
lvermectin is a synthetic derivative of Streptomyces avermitilis. It was developed by Merck & Co. as an antihelminthic for livestock and later found to be safe and effective in humans as a microfilaricide in Onchocerca volvulus infection. The mechanism of action is not clearly established, but the clinical effect is the rapid elimination of microfilariae from the skin after a single oral dose of the drug. This is followed by a more gradual disappearance of microfilariae from the cornea and anterior chamber. There are minimal systemic or ocular side effects, and a single dose is effective for six to 18 months. The adult worm is not affected, and since the female lives for 12 to 15 years, a single annual dose of ivermectin taken for 15 years should free the victim of the effects of infection. During this time a fly feeding on a treated individual should have a much reduced chance of ingesting a microfilaria, thus breaking the chain of transmission. The health workers are delighted to have this new drug available to combine with the spraying campaign in a more rapid extension of the control program to new areas. There are many questions still to be answered and the road ahead appears at least as long and hard as that already past, but there are experts now who believe that the final conquest of onchocerciasis is a matter of time and hard work. Finally, let us not fail to see that this enormously complex and expensive international effort is pointing us back to a great joy of medicine, the relief of suffering without thought of return.
He listened to what the French entomologist and I had to say. As we walked back to his aeroplane with him he said "Obviously I can't promise you anything off the cuff, but I shall do my best for you." That visit was the final act needed to open the international treasure chests and produce the very large sums needed for onchocerciasis control.
The program started in 1974 and is expected to last into the 1990s. The teams combating onchocerciasis were tremendously encouraged two years ago when Merck & Co. announced that it would make ivermectin available free of charge, as much as might be needed to complete the battle against river blindness.
85
Reprint requests to Frank C. Winter, M.D., Christian Eye Ministry, P.O. Box 9774, San Diego, CA 92109.
References 1. Epidemiology of Onchocerciasis. Report of WHO Expert Committee, Technical Report Series No. 597. Geneva, World Health Organization, 1976. 2. WHO Expert Committee on Onchocerciasis. Third Report. World Health Organization Technical Report Series No. 752. Geneva, World Health Organization, 1987.