Drinking Water Quality and the Geospatial Distribution of Notified Gastro-Intestinal Infections

GRILC, Eva; GALE, Ivanka; VERŠIC, Aleš; ŽAGAR, Tina; SOCAN, Maja

According to the results of our study, water contamination with E. coli primarily affected users of small supply zones, serving between 50 and 1000 users in rural areas, as they were 1.25 times more likely to get sick, compared with those who use safe water. The supply zones with more than 10 000 users are less often contaminated, and, if they are, E. coli was found in less than 10% of the water samples taken. The risk for AGI in the larger supply zones was lower for those users who were supplied with contaminated water -an unexpected finding which is difficult to interpret. It may be that users in large supply zones (mainly in bigger cities) are inclined to drink bottled water and, therefore, the temporary contamination does not have an augmenting effect on AGI. Another possible explanation might be that larger water supply systems are better controlled, that any change in water quality is detected immediately, and that consumers are instructed not to use water for drinking/cooking without boiling.