Only one outbreak was reported for the 1989-1990 period. The Atlanta-based agency said it was surprised to find that about 18 percent of respondents in one state continued to swim while suffering from diarrhea. Most of the recent outbreaks of diarrhea linked to swimming pools were caused by Cryptosporidium, a microscopic chlorine-resistant parasite. Pools become contaminated during fecal accidents, often by young children still in diapers. The CDC said people should refrain from swimming until two weeks after diarrhea had stopped.
Swimming is the second most popular exercise in the United States.
Americans make between 360 to 400 million visits to swimming pools each year, especially during the hot summer months.