MINNEAPOLIS (WCCO) — Many people these days are participating in ‘tough mudders’ to stay fit in a fun way. But they may want to practice keeping their mouths shut.

A new report from the Centers for Disease Control and Prevention showed that 22 people contracted a diarrheal illness after swallowing water contaminated with C. coli bacteria from animal feces during a Tough Mudder in Nevada in October 2012.

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“I thought about the chances of getting injured but not sick, I mean, that’s really kind of scary,” said Sammi Oelke, who is training for her first Tough Mudder.

Twin Cities in Motion Executive Director Virginia Brophy Achman says any type of race should involve pre-planning to ensure the route is safe for runners. In 2013, Team Ortho built their own mud ditch using fresh water and dirt to make sure it was bacteria free for their Go Commando 5K.

“Trying to find a location that has a field that isn’t used, you know, with animals,” Brophy Achman said.

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The Minnesota Department of Health released a statement:

“The Minnesota Department of Health has long advised people swimming or playing in recreational waters to avoid ingesting the water, whether from swimming pools or natural bodies of water, because of the potential risk of illness from a variety of possible pathogens. The same would certainly hold true for muddy waters of the type found in such races as the Tough Mudder. In addition, do not participate if you have been sick with vomiting or diarrhea, just as you should not go into a swimming pool. Race organizers should be cognizant of the disease risk and avoid having the course in areas that have livestock (and therefore, livestock manure). Race organizers should inform participants of the potential disease risk.”

Bottom line: Take your own precautions.

“Ask questions, find out what the course is, and you got to make your own decisions,” Brophy Achman said.

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“I’ll try not to drink the water,” Oelke said. “I’ll probably just be way more cautious.”