Participants in Touch Mudder fell ill after ingesting feces-contaminated mud.
The "long distance obstacle adventure race" was held at the Nellis Air Force Base Public Health Flight (Nellis Public Health), near Las Vegas, a Centers for Disease Control and Prevention (CDC) news release reported. In the race competitors often fall face-first into the mud.
Health officials determined there were 22 cases of Campylobacter coli infection in people who had participated in the race.
The CDC said both public health agencies and race organizers should inform participants of the potential health risks.
"Campylobacter is one of the most common causes of diarrheal illness in the United States. Most persons who become ill with campylobacteriosis get diarrhea, cramping, abdominal pain, and fever within [two to five] days after exposure to the organism," the CDC said in the statement.
In some cases the diarrhea is bloody and can come with accompanying symptoms such as nausea or vomiting.
The organism is believed to have entered the surface water of the race site through cattle or swine feces. The illness is more commonly contracted from consuming undercooked poultry or contaminated drinking water.
Muddy obstacle races have been gaining popularity in the United States, about 1.5 million people participated in them in 2012 alone; many of the participants were military personnel.
"Warning participants in outdoor sporting events who might be exposed to fecally contaminated water or slurry that potentially serious diarrheal disease can result if ingested, even inadvertently, could reduce exposures to these pathogens. Event organizers should consider including the risk for waterborne outbreaks in their participant waivers and advise participants to avoid drinking or swallowing unsafe water. Participants also need to be encouraged to seek appropriate medical care for postcompetition diarrhea, especially bloody diarrhea, and to inform medical personnel of their exposure," the CDC stated.
