Combined methods for the study of water contact behavior in a rural schistosomiasis-endemic area in Brazil

A new combined methodology consisting of direct observation and two types of interviews (internal and external interviews) was evaluated for use in exposure risk assessment in schistosomiasis. Specific objectives were to determine its usefulness in achieving equitable coverage of gendered exposure risk and its efficiency in identifying water contact behavior in a rural area in Brazil with different settlement patterns, land use and domestic water supplies. Of the 2476 water contacts recorded, 1223 (49.4%) were identified by direct observation, 946 (38.2%) by internal interviews and 307 (12.4%) by external interviews. Significantly longer mean durations of contacts were recorded for females and greater mean percentage of body surface exposed for males (P < 0.01), reflecting differences in gendered water contact activities. Direct observation identified slightly more male contacts, external interviews significantly more male contacts (P < 0.006), and internal interviews moderately more female contacts. The three methods recorded mean numbers of contacts and mean TBM (total body minutes) per person, declining with age. Significant differences were found between the three methods in regard to frequency and/or intensity of washing clothes, fetching water, washing utensils, washing multiple parts of the body, and bathing. The three methods also recorded differentially frequencies and exposure intensities in the three study communities, among different age groups, by gender and for individual study members. These activity-, locality-, age/gender- and person-specific patterns reflect the relative efficiency and complementarity of the three methods in settlements with different land use, access to streams and water supplies.