The comparative study of patterns of Guinea worm prevalence as a guide to control strategies

Guinea worm, a parasite found in unprotected drinking water sources, causes considerable morbidity and loss of agricultural production among rural people in India and West Africa. A comparative study of village level prevalence data in the two regions reveals marked contrasts in the level and characteristics of prevalence which are useful guidelines in planning control strategies where little is known about local guinea worm epidemioloy. Prevalence rates of up to 75-80% of the total population of a settlement have been found in West Africa, far higher than those in India. The higher figure indicates that all members of a community are exposed to a common infected drinking water source. Here the infection affects all sections of the population who do not treat their water at the household level. In India levels of prevalence for males are far higher than for females, whereas in West Africa the difference in infection rates between the sexes is less marked. In India many men are infected when they are away from the village, attending festivals or farming, and exposed to untreated water sources; women and children travel less and use domestic water sources which are more likely to be treated in some way. Differences in prevalence characteristics according to age, sex or social/economic grouping should be taken into account when planning national and local control campaigns. For example, in Nigeria where women are as likely to suffer from the infection as men, women are the main water collectors and contaminators, and are responsible for domestic water treatment; thus they should be fully involved in control campaigns. Where village level rates are high, community co-operation will be effective as all residents recognize the severity of the guinea worm problem, and a dramatic fall in prevalence rates is possible. Although the complete eradication of the disease in West Africa will be complex because of its widespread distribution and the many sources of infection, the prospects for the eradication of guinea worm are good.