Denver International Airport on red alert as three passengers are diagnosed with world’s most infectious disease

Health officials are sounding the alarm after three cases of measles were detected at Denver International Airport. 

An infected individual arrived at the airport after a Turkish Airlines flight on May 13 and stayed in a nearby hotel May 13 and 14, potentially exposing hundreds of patrons.

The Colorado Health Department also confirmed two additional cases of measles on the flight, Turkish Airlines Flight 201. 

One was an out-of-state traveler who was infectious during the flight and the other a young child under five years old who was likely exposed on the plane.

The first passenger contracted measles despite being vaccinated, which occurs in just three percent of measles cases. The health department said vaccinated individuals tend to have milder symptoms.

The child was unvaccinated and is currently hospitalized, while the vaccination status of the third passenger is unclear. 

The health department warned anyone who was at Denver International Airport, which serves 226,000 passengers per day, on May 13 or 14 should monitor symptoms for 21 days and call their healthcare provider. 

Measles is the most infectious disease in the world, with a patient able to infect nine out of ten unvaccinated people that are exposed.

Measles, which causes a signature blotchy rash, has infected 1,000 Americans so far in 2025 (stock image)

Symptoms – which include a blotchy rash, fever, cough and runny nose – typically develop seven to 21 days after initial exposure. 

Measles spreads via airborne droplets released in coughs and sneezes, which can hang in the air for up to two hours after a patient passes.

It is particularly dangerous to young children, with the CDC saying one in 20 unvaccinated children who are infected develop pneumonia while one in 1,000 suffer from encephalitis — swelling of the brain that can cause permanent damage.

One to three in every 1,000 unvaccinated children who are infected die from the disease.

Colorado has now detected seven total cases of measles.  

There is renewed emphasis on measles this year amid a major outbreak in West Texas that is the country’s largest in two decades.

A total of 717 people have been sickened by the outbreak in Texas alone this year, with officials updating case tallies every Tuesday and Friday.

And the US has now crossed a grim milestone nationwide, with more than 1,000 measles cases being recorded — only the second time this threshold has been crossed since the disease was declared eradicated in 2000.

Two young girls, aged six and eight years, have also died from the disease.