Improving waterborne disease outbreak investigations

This article is a summary of discussions held and recommendations made at a workshop for the investigation of waterborne disease outbreaks in Chapel H ill, North Carolina, December 7-8, 1998. Suspected waterborne outbreaks in the United States are primarily investigated by state and local public heal th officials who may infrequently conduct enteric disease outbreak investig ations. Thus, it is important that officials have a formal plan to ensure t hat epidemiological studies are methodologically sound and that effective c ollaboration occurs among the epidemiologists, scientists, and engineers wh o will conduct the investigations. Laboratory support to analyze water samp les and clinical specimens should be arranged well in advance of when servi ces may be needed. Enhanced surveillance activities can help officials reco gnize additional outbreaks and initiate investigations in a timely manner. Epidemiologists should pay more attention early in the investigation to stu dy design, questionnaire development, and sources of bias, especially recal l bias, that may affect the interpretation of observed associations. Improv ed investigations can increase our knowledge about important etiological ag ents, water systems deficiencies, and sources of water contamination so tha t waterborne outbreaks can be more effectively prevented.