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

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

The quality of drinking water might, at least partially, be an explanatory variable for the geographical differences in the incidence of AGI in 2010. Notified water-borne outbreaks (WBOs) are rare in Slovenia -there were 86 WBOs registered between 1981 and 2010 (21). Shigella flexneri and sonnei were the predominant pathogens in the first decade, causing half of the WBOs. The number of notified WBOs has declined in recent years and the aetiology has changed (25) . There were only one to two WBOs per year in the last ten years, and most of them were caused by viruses (most often noroviruses) (21). Noroviruses were identified as an important cause of outbreaks in different settings, including WBOs also in Sweden (26) . Craun and co-workers (2010) comprehensively described outbreaks associated with drinking water in the US from 1971 to 2006. A drop in the number of notified outbreaks related to drinking water has been observed as well, especially in public systems. The decline was attributed to improved infrastructure and the impact of national regulations (27) . Individual water systems and systems supplied by ground water were more at risk of contamination (27) . A high prevalence of enteric viruses has been found in untreated individual drinking water sources in Slovenia as well (28) . Drinking water quality in Slovenia is generally good, especially in large water supply zones, but it is not of the same quality in all parts of the country: microbiological problems are found in small water supply zones in rural areas, and contamination with nitrates and pesticides in some areas with extensive agriculture (the North-Eastern part of the country). Without doubt, it has not been significantly improved in the 2004-2010 period (16) .