Cross-contamination of distributed drinking water as the cause of waterborne outbreaks in Armenia 1992-2010

Investigations and established causal relationship of waterborne outbreaks (WOs) from developing countries and countries in transition are sparse and mainly centered on agents, such as from Vibrio cholera and Shigella dysenteriae. Information, however, prevails in countries like Armenia with an epidemiological system in place. Groundwater is the main drinking water source (96%); water is delivered intermittently 12-14 hours per day. In 2005 about 7% of all infant deaths were attributed to intestinal infectious diseases. Recorded information on WOs and supply systems (1992-2010) was obtained from published official sources, from 'gray-literature reports', primary data collection from statistical records and through personal communication. Epidemiological descriptive analysis was made and Geographical Information System (GIS) applied for results visualization. In-depth outbreak analysis was conducted on selected cases. Overall, 104 WOs caused by different etiological agents were revealed. The main drinking water source in areas where outbreaks occurred was the centralized water supplies (69.2%) based on GIS mapping. The major cause of outbreaks was the cross-contamination of drinking-water distribution by wastewater. In Armenia the main areas to be addressed for the future are: service quality, source protection, delivery interruption and subsequent microbial contamination.