The risk of schistosomiasis infection and heavy infection in
the locality of Sabugo was evaluated in relation to housing in
areas with different urbanization development and to
residential supply with snail-infested water. Critical
sanitary conditions were found in areas of incomplete
urbanization, where healthy water supply sources were scarce,
and draining of sewage, without previous treatment, was made
directly to the water-bodies used for domestic and leisure
activities, despite being Biomphalaria tenagophila snail
breeding-places. Stool examinations (Kato-Katz and Lutz
methods) showed prevalence of 2.9%, mean intensity of 79 eggs
per gram of stool and 47% of positive cases presenting intense
infection. The use of snail-contaminated water for domestic
purposes was considered a risk factor for infection. It is
concluded that incomplete urbanization would facilitate
transmission, probably enhancing the intensity of infection
and that a low prevalence could hide a highly focal
transmission. The relevance of these facts upon the efficiency
of epidemiologic study methods and disease control planning
are then discussed.
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