Epidemiologic trends in outbreak reporting and emerging public health challenges associated with drinking water in the United States

Background: The U.S. has one of the safest drinking water supplies in the world, but changing epidemiologic trends in waterborne disease and emerging water resource challenges indicate that new analytic and policy approaches are needed to protect public health.

Methods: We analyzed data from the U.S. Waterborne Disease and Outbreak Surveillance System (WBDOSS) on drinking water outbreaks reported during 1971–2006 and assessed emerging drinking water-related public health challenges.

Results: During 1971-2006, 780 drinking water outbreaks were reported in the U.S. resulting in 577,094 illnesses and 93 deaths. Of outbreaks with known etiology (N=431), Giardia intestinalis (29%), Shigella (10%), and norovirus (8%) were the most frequently identified pathogens. However, since its inclusion in WBDOSS in 2001, Legionella has been the most frequently reported waterborne disease pathogen, accounting for approximately 29% of all reported drinking water-associated outbreaks during 2001–2006. The majority of drinking water outbreaks were associated with treatment deficiencies (40%), untreated groundwater (31%), and distribution system deficiencies (10%). Community municipality (22%) and camps/cabins/recreational areas (18%) were the most common locations for drinking water outbreaks.

Conclusions: Recent outbreak data indicate that issues outside the U.S. regulatory framework (e.g., Legionella spp. associated with premise plumbing and contamination of private wells) will require more targeted disease prevention efforts. Increased sensitivity of disease surveillance systems, advances in pathogen detection and control, and preparation for emerging water-related challenges—climate change, aging water infrastructure, water shortages, and the potential emergence of newly identified waterborne disease pathogens and chemicals—will be necessary to protect public health.