| Opportunities for Control of Dracunculiasis (1982) |
|Overview of Dracunculiasis|
Dracunculiasis is a parasitic infection caused by a long, stringlike, female worm--the nematode Dracunculus medinensis. Its larval form infects an intermediate crustacean host (Cyclops, a water flea) that commonly infests shallow ponds or step wells used as sources of human drinking water. Known to cause human suffering since ancient times, the infection was referred to by physicians as early as the Graeco-Roman era and by Arab physicians in medieval times. Common names include guinea worm and Medina worm. The worm was classified by Linnaeus in the eighteenth century. Fedchenko, a Russian naturalist, described the life cycle in 1869--the first time an invertebrate (arthropod) intermediate host was described for any parasitic disease of man.
Dracunculiasis belongs to a group of water-based diseases that includes malaria, onchocerciasis, and schistosomiasis. All of these diseases depend in some way on water as the natural habitat of an intermediate host. Unlike the others, however, dracunculiasis is transmitted only through drinking contaminated water and does not have any alternate pathways for infection. Thus, it is the only water-based disease that can be entirely prevented by protecting supplies of drinking water.
Dracunculiasis still represents a serious health risk for several millions of rural villagers in parts of Africa, the Middle East, and India. It affects only the rural poor who lack safe sources of drinking water for their households and places of work (agricultural plots). These people also often suffer from other parasites, trachoma, infant diarrheas, severe respiratory infections, and malnutrition, all of which are mayor health problems associated with poverty.
Unlike most communicable diseases in developing countries, the greatest morbidity from dracunculiasis occurs in adults. This may be the reason it has received less attention than those illnesses resulting in high morbidity and mortality in children. Because peak case rates often coincide with such agricultural activities as clearing land, planting, and harvesting, the disease is a mayor cause of agricultural work loss in many areas. Infected individuals are often crippled or disabled for many weeks each year from painful ulcers produced by the worms' emergence and complications resulting from secondary bacterial infections.
Public health authorities in endemic countries may be unaware of the annual incidence of dracunculiasis, because most patients do not attend clinics and therefore are not reported. The true burden of illness is seldom recognized, since almost no deaths occur as a result of the parasitic infection. However, reported numbers of cases and special epidemiologic studies have yielded rough estimates of the number of people at risk for acquiring dracunculiasis that range from 10-48 million throughout the world.