Outbreaks of Waterborne Disease in the United States: 1989–90

For the two‐year period 1989–90, 16 states reported 26 outbreaks of waterborne disease from water intended for drinking. These outbreaks resulted in illness in an estimated 4,288 people. Giardia lamblia was implicated as the etiologic agent for seven of the twelve outbreaks in which an agent was identified. The outbreaks of giardiasis were all associated with ingestion of unfiltered surface water or groundwater influenced by a surface water. An outbreak with four deaths was attributed to Escherichia coli O157:H7, the only bacterial pathogen implicated in any of the outbreak investigations. An outbreak of remitting, relapsing diarrhea was associated with cyanobacteria (blue‐green algae)‐like bodies, whose role in causing diarrhea1 illness is being studied. Two outbreaks caused by hepatitis A and one caused by a Norwalk‐like agent were associated with use of well water. National surveillance of outbreaks of waterborne disease, which has been conducted for two decades, continues to be a useful means for characterizing the epidemiology of waterborne diseases.