[Quality of potable water and incidence of gastroenteritis in 2 cities in the state of Sonora, Mexico].

Based on the fact that drinking-water is of great significance in the transmission of infectious diseases, the incidence of diarrheal disorders was examined in two cities similar in their demographic composition and in their use of health services, but not in the quality of the drinking-water supply. In Navojoa, a city with high incidence of diarrheal diseases (116/1000 pop. in 1985), high rates of drinking-water contamination with fecal coliforms were found (43% of water samples); on the contrary, in Ciudad Obregón, a city with lower rates of diarrheal diseases (49/1000 pop. in 1985), drinking-water contamination with fecal coliforms was also comparatively lower (only 6% of water samples). These data illustrate the need to promote the implementation of drinking-water treatment in those places with signs of fecal contamination and high incidence of diarrheal diseases. To this regard, the General Direction for Research and Technological Development of the Ministry of Health has promoted the development of a chlorination equipment, useful mainly in rural areas, where biological contamination is usually high. These and similar procedures for water treatment should be considered as effective means to decrease the incidence of diarrheal diseases.