A three-state study of waterborne disease surveillance techniques.

For a two-year period, the states of Colorado, Vermont and Washington tested the effectiveness of ten surveillance methods for identifying waterborne disease. Nine were active surveillance methods, soliciting illness reports; one was passive, relying on voluntary disease reporting. One waterborne disease outbreak was identified through use of the nine active methods, while 14 were reported through the passive surveillance method. The presence of coliform bacteria during routine water testing was not related to illness in the community.