LAS VEGAS (May 2, 2014) The U.S. Centers for Disease Control and Prevention has a warning for people who take on extreme obstacle courses such as the Tough Mudder.
The CDC issued a memo this week that warns that animal feces in the muddy water along the courses can give participants a bad case of diarrhea.
CDC officials say nearly two-dozen people reported that they became sick after participating in a muddy race in October 2012 in rural Beatty, Nevada.
The investigation traced the sickness to the bacteria campylobacter coli, and concluded people became sick after accidentally swallowing contaminated water.
Health officials say adventure races in the U.S. drew about 1.5 million participants in 2012.
Participants face obstacles such as leaping over a wall of flames and slithering on their bellies through mud.