Health officials are investigating an outbreak linked to Colorado’s largest stock show after 20 people, including 17 kids, came down with E. coli O157.

Chris Urbina with Denver Public Health said a lab has confirmed 20 E. coli cases but the number is expected to grow.

The Colorado Department of Public Health and Environment said in a news release,

"While the investigation is ongoing, we suspect that these infections are linked to attending the National Western Stock Show, which was held in Denver from Jan. 10 to Jan. 25.”

Although health officials haven’t pinpointed the exact cause of the E. coli, the common denominator in all the cases is the stock show, Urbina said.

Many schools and child care centers organized trips to the stock show, and many children attended with their families, so there is the potential that the number of cases could jump, health officials said.

On Wednesday, the CDPHE sent a letter to daycare centers alerting them to the outbreak and asking the staff to take special precautions.

For disease reporting or other questions please contact the CDPHE Communicable Disease program at 303-692-2700.