Officials from the CDPHE warned about a possible measles exposure at Denver International Airport in Concourse C.

Of Colorado’s 21 cases, more than one has been reported in Arapahoe, Adams, Denver, El Paso and Mesa counties. Two-thirds were unvaccinated people or those whose status was unknown. Four cases have been in kids younger than 4, the rest have been in adults. The state reports five people have been hospitalized; no one has died.

People across Grand Junction, a gas station in Fruita and travelers who flew to and from Denver International Airport last week could have been exposed to measles, state health officials said Monday.

Also, Colorado reported a second infection from Mesa County, and in Montana, the first case in decades was reported from the Helena area.

Measles symptoms include a fever, runny nose, red eyes, cough and a rash that typically starts on the face. Most people become contagious about four days before the rash appears, so they could inadvertently infect others while thinking they have a less serious disease.

The CDPHE and the Adams County Health Department have confirmed the case of measles in a child under 5 years from Adams County.

Health officials confirm a second measles case in Mesa County and a possible measles exposure at Denver International Airport in an out-of-state traveler.

In a press release, the Colorado Department of Public Health and Environment said that in conjunction with Mesa County Public Health, the agencies found that the adult resident had no “known connection to other recent exposures reported in Colorado and has not traveled outside the state.”

An Adams County child is in the hospital with measles, and Colorado public health officials warn of possible exposure at Children’s Hospital.

Health officials in Grand Junction are investigating possible community transmission of measles after an unvaccinated man contracted the virus.