New initiatives in the control of helminths.

Over the last decade, intestinal nematode infection has become increasingly recognized to be an important and soluble public health problem. The availability of benzimidazole anthelmintics has been a major contributor to this perception, not only because they have made single dose cure a reality but also because the broad spectrum of activity allows infection with Ascaris, Trichuris, the hookworms and other common nematodes to be tackled as a single disease entity. From this perspective, the disease caused by the 1000 million infections due to multiple geohelminth species is difficult to ignore. On this scale of infection even mortality, which is acknowledged to be a very rare consequence of helminth infection, assumes substantial proportions: current estimates suggest that more than 150 000 avoidable deaths occur each vear due to geohelminthiasis, which bears comparison with global mortality due to diseases more traditionally viewed as lethal (e.g., African sleeping sickness is estimated to have an annual death toll of less than 4000). The large burden of geohelminthiasis has even more profound public health consequences in terms of morbidity. Careful clinical and enidemioloaical studies have demonstrated that chrohic infect&r with the maior geohelminths persists, and is most intense, throughout the vulnerable vears of childhood. with insidious effects on growth and development. More importantly , they have demonstrated that these effects are largely reversible by simple therapy. The traditional argument, that therapy is irrelevant to the control of helminth disease because children become reinfected, is difficult to sustain in the face of the remarkable catch-up growth achieved by some children after a single treatment. Much of the reassessment of the public health importance of these infections was stimulated by the World Health Organization (WHO) reactivating, in 1980, a program&e for the control of inte&al oarasites (WHO. 1981). Desoite considerable efforts. however, the translation of policy into action has been slow to occur. The difficulty is one of scale: the exceptional prevalence of geohelminthiasis, which iustifies intervention, also nresents exceotional loais-tic difficulties for the design of control programmes. While the cost of individual treatment is low. the total cost of treating such large numbers of infections becomes substantial, and has to compete for scarce resources in the endemic countries. The recent initiatives for control have addressed this problem, not by elevating the priority of geohelminth infection which is difficult to justify in the presence of continuing morbidity due to malnutrition, diarrhoea and vaccine-preventable diseases-but by setting …