Acceptance and use of communal filtration units in guinea worm eradication.

The use of cloth to filter drinking water for guinea worm prevention is a long-standing control strategy and part of a mixed approach that includes the provision of wells, chemical treatment of ponds and protection of water supplies. As the goal of eradication nears, filters are a useful component of the quick response needed to implement case containment at village level. Various designs of filters have been used. Individual hand-sewn filters (HSFs) using monofilament nylon cloth have played a central role in village-based control to date. Problems such as the need to continually reinforce correct habitual filtering behaviour have led to the design and testing of communal filtration units (CFUs) made from metal oil drums with filter cloth inserted in the top and spigots at the bottom. Approximately one year after the introduction of CFUs in the South-western Zone of Nigeria, village surveys were conducted to determine opinions about the two types of filters and reported use. Percentage use was calculated by dividing the number of times water was filtered in the week preceding the survey by the number of times water was collected in that week. Those respondents with access to CFUs filtered an average of 91.9% of the time compared to 75.7% of those with HSFs. Using the village as level of analysis since it was the main level of intervention, the average percent of times villagers in CFU villages filtered was 91.1% compared to 77.8% in HSF villages. Although CFUs were more expensive in the short run, their greater acceptance by villagers is a factor to recommend their wider implementation to speed up elimination of guinea worm from Nigeria.