Las Vegas, NV (KTNV) -- The Southern Nevada Health District has confirmed norovirus in two people who became sick while in Las Vegas last week.
The two cases of norovirus were confirmed through testing of stool samples.
18 people who were staying at the Rio hotel and casino were transported to a local hospital after becoming ill last Friday morning.
The people who became sick were in Las Vegas for a youth football tournament held at locations around the valley. Despite the illness, some players were able to participate in the tournament.
"Football would probably be pretty high risk for people if they were playing while they're ill," said Nancy Williams, epidemiologist for the Health District.
The source of the illness has not been determined and Williams said we may never know the exact source since the virus spreads quickly and easily.
"It's so common, it could come from anywhere," said Williams. "It's very hard to pinpoint an original source."
Justin Gates, competition director for Sports Network International, said between 90 and 100 people became sick from up to nine different teams. The health district said it did not have an exact count on the number sick.
The norovirus infection is characterized by nausea, forcefull vomiting, diarrhea and abdominal pain.
The health district handed out a norovirus fact sheet at a meeting late Friday night.
The Rio helped people who were sick get medical assistance and some guests may have already been sick when they arrived at the hotel, said Gary Thompson, director of corporate communications for Caesars Entertainment in a statement.
The health district inspected all of the Rio's food outlets and they are not believed to be the cause, said Thompson.
While no similar illness has been reported at other Caesars properties in Las Vegas, "we have taken several steps to assist guests and employees and have voluntarily implemented strict norovirus prevention protocols at all of our properties here," according to the statement.
Click here to read the full statement from Caesars regarding the incident.
Williams said people who got sick were also staying at other hotels around the valley.
Gates said organizers will likely issue reminders to participants ahead of the next tournament to take precautions and avoid another outbreak.