FIRST REPORTED OUTBREAK IN THE UNITED-STATES OF CRYPTOSPORIDIOSIS ASSOCIATED WITH A RECREATIONAL LAKE

In the summer of 1994, an outbreak of cryptosporidiosis occurred among visitors to a state park in New Jersey. We enrolled 185 persons in a cohort study, 38 (20.5%) of whom had laboratory-confirmed cryptosporid iosis or gastrointestinal illness that met our clinical case definitio n. Having any exposure to lake water (e.g., swimming) was strongly ass ociated with illness (P < .001), The outbreak lasted 4 weeks and affec ted an estimated 2,070 persons, The most likely sources of the outbrea k were contaminated runoff of rainwater and infected bathers, This out break of cryptosporidiosis is the first reported to be associated with recreational exposure to lake water. Our investigation shows that eve n a large and ongoing outbreak may not be detected for several weeks, Health professionals and persons at high risk for severe cryptosporidi osis should be aware that recreational water can be a source of crypto sporidium infection.