Culturally perceived illness and guinea worm disease surveillance

Surveillance is a central component of the international guinea worm eradication effort to aid planning, monitoring and certification of disease elimination. The programme is based on a standard case definition of 'a person exhibiting or having a history of a skin lesion with emergence of a guinea worm'. Local names for and cultural conceptions of the guinea worm illness experience vary from this definition, either by being non-specific or inclusive of other presentations, thus setting the stage for false positive case reporting. False reports have serious implications on decisions to allocate disease control resources, especially in the remote regions where guinea worm is endemic. A recent case search in one district of southwestern Nigeria provided an opportunity to determine the prevalence of the various cultural manifestations of guinea worm. Only 65% of total cases reported matched the standard case definition. Furthermore, an additional 26% of small farm villages would have been targeted for programme intervention, had interviewers not verified positive responses. Previous work had shown that local health staff were not sensitive to the importance of the case definition. Thus there is need, not only for ethnographic study preceding design of surveillance activities, but also for the involvement of local health staff in this process to increase their commitment to and understanding of eradication efforts.