ABSTRACT
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.
Subject(s)
Endemic Diseases , Fresh Water , Rural Health , Schistosomiasis mansoni/epidemiology , Water Supply , Water , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , Animals , Baths , Brazil , Child , Child, Preschool , Female , Fresh Water/parasitology , Health Surveys , Humans , Laundering , Male , Middle Aged , Schistosomiasis mansoni/parasitology , Schistosomiasis mansoni/transmission , Sex Factors , Water/parasitologyABSTRACT
A total of 256 sites in 11 habitats were surveyed for Biomphalaria in Melquiades rural area (State of Minas Gerais) in August and November 1999 and in March 2000. Of the 1,780 Biomphalaria collected, 1,721 (96.7 percent) were B. glabrata and 59 (3.3 percent) B. straminea. Snails were found in all habitats except in wells, with the largest mean numbers in tanks, seepage ponds and canals, and the smallest numbers in springs, rice fields and fishponds. People's knowledge of the occurrence of Biomphalaria at the collection sites and the presence of Biomphalaria ova were strongly correlated with the occurrence of snails, and distance between houses and collection sites, as well as water velocity were inversely correlated with Biomphalaria occurrence (p < 0.001). The strongest predictor o f Biomphalaria occurrence was the presence of tilapia fish in fishponds. Fourteen Biomphalaria (0.8 percent of all snails) found at 6 sites were infected with Schistosoma mansoni. Suggestions are made for the utilization of local people's knowledge in snail surveys and further studies are recommended on the possible use of tilapia for biological control of Biomphalaria in fishponds, as well as modeling of S. mansoni transmission and reinfection
