OKLAHOMA CITY — State health officials confirmed Wednesday that a stretch of the Oklahoma River was to blame for sickening at least 45 triathletes last month, saying the water was filled with parasites, viruses and other contaminants associated with animal and human waste.

The Oklahoma State Department of Health said tests on stool samples from the athletes confirmed such contaminants as norovirus and “a couple of different kinds of bacteria and parasites.” The agency said the findings were consistent with waterborne human or animal waste.
There were 367 participants in the May 16-17 Boathouse International Triathlon, which was held after a heavy rain and included a 1.5-kilometer swim. A total of 218 responded to a health department survey and of that number, 45 reported symptoms including diarrhea, vomiting and fever.
Debbie Ragan, a spokeswoman for Oklahoma City’s utilities department, has said water samples taken May 15 near the swim course showed an E. coli count of 573 per 100 milliliters. State officials say the standard safe level during events where water might be swallowed is 126.
The river, formerly a ditch that handled runoff, was transformed in recent years into a prime venue for rowing events, but this was the first time a triathlon had been held there.
“The amount of time spent swimming in the river during the practice sessions and during the event is the only significant exposure associated with the development of diarrheal illness among participants,” said Lauri Smithee, chief of the health department’s acute disease service.
Mike Knopp, the director of the Oklahoma City Boathouse Foundation, which helped organize the event, said the disease outbreak was unfortunate.
“This is a one-time incident that is specific to triathlon, and event organizers will take every precaution to make sure it doesn’t happen again,” he said.
Before the triathlon, Derek Smithee, the water quality division chief of the Oklahoma Water Resources Board, said a six-mile section of the river near downtown had been listed by the state as “impaired” because of fecal coliform, sulfates and turbidity. He also said this listing didn’t mean the water wasn’t safe for swimming.
Oklahoma City water quality officials began testing the river about six months before the triathlon at the request of race organizers. Bret Sholar, the race director, said he made the final call to conduct the triathlon and said he believed bacterial levels in the river were falling.
“We’ve just learned that there is always a risk in triathlons, especially when you swim in open water,” Sholar said. “We can’t have control over the river. Hopefully the athletes understand that an open water swim has an associated risk.”
He said plans call for the triathlon to be held again next year.