Travellers who passed through Denver International Airport or Los Angeles International Airport on Dec. 11 are at risk for measles after the children tested positive for the disease, public health officials said.

US health officials have confirmed that three children recently hospitalized with measles in Colorado travelled from New Zealand to Los Angeles International Airport before arriving in Denver.

The Denver Post reported Tuesday that the Centers for Disease Control and Prevention has issued warnings at airports in Denver and Los Angeles involving the same airline passengers.

The children who contracted the highly contagious disease did not have the measles, mumps and rubella vaccine and are receiving treatment at Children’s Hospital Colorado, officials said.

People who were at the hospital Dec. 12 between 1 and 7:30 p.m. could have also been exposed, health officials said. It is unclear how many people are at risk of exposure to measles.

Symptoms include high fever, cough, runny nose, watery eyes and a rash, health officials said. The illness can lead to pneumonia and swelling of the brain.