Officials warn measles patients passed through 5 major U.S. airports this month

Affected airports and cities

Chicago: An individual with measles traveled through two terminals at O'Hare International Airport over the course of a week. The person passed through O'Hare's Terminal 1 on Dec. 17 and through Terminal 3 on Dec. 12, according to the Chicago Department of Public Health.

Richmond, Virginia: A person with measles visited Richmond International Airport on Dec. 17, according to the Virginia Department of Health.

Austin, Texas: An individual with a diagnosed case of measles visited the United Airlines gate area at Austin-Bergstrom International Airport on Dec. 17, Austin Public Health reports.

Denver and Los Angeles: Three unvaccinated children traveled to a country with an ongoing measles outbreak in early December and tested positive for measles when they returned.

• The children visited parts of Denver International Airport on Dec. 11, including Concourse A, the baggage area and the pickup area, Colorado's Tri-County Health Department reported.
• The children also traveled through Terminals 4 and 5 at Los Angeles International Airport on Dec. 11, according to the Los Angeles Department of Public Health.

What they're saying: "A small number of [measles] cases are capable of quickly producing epidemics," Dr. Mark Escott, medical director for Austin Public Health, said in a statement.

The big picture: 2019 has been the worst year for measles cases in more than two decades. The CDC has so far confirmed 1,276 cases in most U.S. states.

• Globally, the United Nations has so far confirmed 440,263 cases this year, up from around 350,000 cases in 2018, Axios' Marisa Fernandez reports.

Go deeper:

• Over 140,000, mostly children, died from measles in 2018
• Germany makes measles vaccine mandatory
• Measles can give your immune system amnesia