Waterborne disease outbreak from drinking water contamination, Albania, July 2024: A case study

Most waterborne outbreaks are caused by faecal microbiological contamination, often detected through indicator organisms such as Escherichia coli and Enterococcus spp., which serve as reliable proxies for the presence of enteric pathogens. Noroviruses are widely recognized as a major viral cause of acute gastroenteritis and are frequently implicated in waterborne outbreaks due to their low infectious dose, environmental stability, and resistance to conventional water treatment processes. This descriptive study aims to assess the public health impact of a waterborne outbreak linked to contamination of the water supply system in Bulqiza, Albania, during July 2024. Field investigations included microbiological and physicochemical analyses of drinking water, as well as measurements of residual chlorine levels. The strong spatiotemporal association between contaminated water and reported cases support a waterborne transmission route. A total of 441 gastroenteritis cases were reported, primarily among city residents (54.6%), with additional cases among daily commuters from surrounding villages (18.2%) and non-resident visitors (17.2%). The results revealed multiple violations of microbiological quality standards and a lack of residual disinfectant in several samples, indicating contamination of the water supply. Laboratory testing of patient specimens confirmed Norovirus GII as the primary aetiological agent. This outbreak highlights the critical need for reliable water infrastructure, consistent disinfection practices, and prompt public health responses. The findings emphasize the importance of sustainable water management, improved intersectoral coordination, and prevention strategies aligned with international water safety standards.