Drinking water security in the 21st century: Revisiting the lessons from Milwaukee's cryptosporiduim outbreak

Drinking water security remains a high priority for the U.S. Environmental Protection Agency (USEPA) and U.S. Department of Homeland Security. Early warning and detection of a drinking water contamination event by public health or water utility authorities is a fundamental goal of the USEPA Water Security Initiative (WSI). The WSI encompasses a multifaceted approach that is focused on design, implementation and evaluation of methodologies and systems that are protective and responsive to the intentional introduction of biologic or chemical agents within drinking water distribution systems. The 1993 cryptosporidiosis outbreak in Milwaukee, WI, remains one of the largest waterborne disease outbreaks in modern U.S. history. Over 400,000 persons became ill – and 100, primarily immune-suppressed individuals, died – as a result of ingesting contaminated drinking water, yet the outbreak was initially undetected by local public health agencies (LPHAs) and the regional water utility. Lessons learned by MHD in the aftermath of the outbreak response can inform the development of response algorithms for the public health surveillance module of the WSI, and provide valuable insight into challenges faced by LPHAs and water utilities that may be common to intentional breaches of water treatment and distribution systems. Further, Milwaukee's quantitative risk-assessment model provides a valuable approach to assessing overall and continued risk of naturally occurring waterborne outbreaks in a community. Data and strategies gleaned from review of experiences like the 1993 outbreak are invaluable in crafting future collaborative and strategic planning by local, regional, and national officials interested in addressing drinking water security.