COLUMBUS, Ohio — Eighteen athletes and one coach from three schools visiting Ohio State for this week's NCAA Division I men's swimming and diving championships have been treated for a gastrointestinal illness.

Dr. Chris Kaeding, Ohio State's head team physician, said Wednesday night that it was a viral infection resulting in nausea, vomiting and diarrhea but no fever. The NCAA would not release the names of the schools or athletes involved.

The championships are set to continue as scheduled, starting Thursday at McCorkle Aquatic Pavilion on the Ohio State campus. Ohio Dept. of Health officials have investigated and approved the facility for use for the meet.

"We are not sure what caused it but it did not come from the pool facility, or host venue," said Kaeding, who believes the illness should run its course in 24 hours. "We are taking extra measures of additional cleansing of the pool."

Ben Jay, a senior associate athletic director at Ohio State, said discussions were held with the NCAA and the meet's sanctioning body was aware of the situation.

Officials were looking into whether the athletes were sick when they arrived at the pool and then spread the illness at practice. They are also trying to determine if all three teams were in a common place prior to the outbreak. The three afflicted teams were staying at different hotels. No one knew for certain if they arrived on the same flight.

"We believe they were sick before they came to Columbus," added Kaeding, who said the first cases of the illness were reported Tuesday night. "I feel pretty comfortable we don't have new cases."

The sick were treated at Ohio State University Medical Center and then released. None were hospitalized, and all are expected to compete.