LAS VEGAS -- The Clark County School District is doing extra cleaning at five schools that were used during the National Youth Football Championship last weekend where around 100 people became ill.
The Southern Nevada Health District has confirmed that some of those cases were caused by the norovirus.
The virus makes its way to the gastrointestinal track, replicates and can cause vomiting, stomach cramps and diarrhea.
It is spread when people get the virus on their hands and then into their mouths.
"It needs to get in a persons mouth in order to become ill because it has to get in your gastrointestinal track meaning you have to swallow it," epidemiologist Nancy Williams said.
It spread quickly through dozens of players, coaches, and parents in Las Vegas for the National Youth Football Championship over the weekend.
The Clark County Fire Department transported around 20 people, who were staying at the Rio Hotel and Casino, to the hospital.
"It is fairly common. Every year to have one team maybe two, but this year it was much more widespread then we've seen in the 42-year history of this event," director of the tournament Justin Gates said.
Cheyenne, Chaparral, Western, Mojave and Canyon Springs high schools all hosted games during the tournament.
Monday night the Clark County School District sent out a message through ParentLink explaining it was working with the health district to disinfect bathrooms and sports facilities against the norovirus.
The message read in part, "while the source of the norovirus is not known, we want to be proactive and take extra efforts to sanitize our facilities."
The SNHD has also ordered the same kind of cleaning at a number of hotels used by players and families during the tournament. It also warned infected people to stay home well after feeling better.
"They should remain away from school or work or any other kind of group environment for 72 hours after their symptoms have resolved," Williams said.
The health district says these precautions should stop the spread.
Several coaches told 8 News NOW said none of the local Las Vegas or Henderson football players came down with the norovirus. They believe it was likely spread at the hotels teams were staying at. Local players luckily went to their own homes after the games.