During the peak holiday travel season, one of the world's most infectious diseases was detected at multiple major U.S. airports.
In December, Raleigh-Durham International, Boston Logan International, Newark Liberty International and Denver International airports all reported measles cases or potential exposure, according to health departments in those areas.
A Massachusetts Department of Public Health (MDPH) spokesperson said the department typically learns of potential measles cases from state healthcare providers or from other public health agencies, including the CDC, when the infection was first diagnosed elsewhere.
WORLD'S MOST CONTAGIOUS VIRUS DETECTED AT TWO MAJOR US AIRPORTS AMID HOLIDAY TRAFFIC
MDPH determines and validates exposure locations and timelines through a combination of patient interviews and reviews of travel itineraries. When exposures may have occurred in public settings such as airports, the agency works closely with relevant authorities.
"Determining locations and times of potential exposure for the public is frequently done in coordination with other authorities," the spokesperson told Fox News Digital.
A New Jersey Department of Health (NJDOH) spokesperson told Fox News Digital that measles cases are immediately reportable.
"[This] means they are to be reported upon suspicion to the jurisdiction where the individual resides," the spokesperson said. "If a clinician suspects measles based on symptoms, they must report it, even without laboratory results."
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A record 8.03 million travelers were expected to fly across America this holiday season, according to AAA.
Confirming a measles case requires either laboratory testing or evidence of direct contact with an established case, according to the NJDOH.
State authorities work with the local health department to conduct "a thorough case investigation," during which the individual is interviewed.
"A suspected case is a situation with a clinical presentation that could be measles, but laboratory testing is not yet completed," the NJDOH spokesperson said. "A probable case is a case with symptoms consistent with measles (and no other more likely diagnosis), but without confirmatory testing or a known link to a confirmed case."
"The local health department works with the individual to develop a complete and accurate timeline of potentially exposed locations."
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To classify cases in Massachusetts, MDPH said it considers multiple factors during a case investigation, such as clinical symptoms, vaccination history, travel history, laboratory data, and evidence of epidemiological links to confirmed cases.
"MDPH requests that providers send two specimen types to the State Public Health Laboratory for testing - nasopharyngeal (nasal) swab or oropharyngeal (throat) swab for PCR and serum for IgM (blood) testing," the spokesperson told Fox News Digital.
If a case is later ruled out or reclassified, public health advisories may be revised as more information becomes available.
As of Dec. 30, there were 2,065 measles cases reported in the U.S., according to the CDC's latest data. Eleven percent of those cases required hospitalization. There were three confirmed deaths from measles in 2025.
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Measles symptoms include a high fever, cough, runny nose, watery red eyes and a rash that usually appears between three and five days after symptoms begin, according to medical sources.
The rash usually begins as flat red spots that appear on the face at the hairline and spreads downward to the neck, torso, arms, legs and feet.
The airborne virus can spread when someone coughs or sneezes. Measles is known to stay in the air for up to two hours after an infected person leaves the area.
Those who believe they might have been exposed during travel or in some other way - particularly if they're not vaccinated or aren't sure about their vaccination status - should immediately reach out to a healthcare professional or health department, experts say.
They should also monitor for symptoms and avoid contact with others.
The CDC notes on its website, "If you do not have written documentation of measles immunity, you should get vaccinated with the MMR vaccine. There is no harm in getting another dose of MMR vaccine if you may already be immune to measles (or mumps or rubella). Your healthcare provider may perform a blood test to check for evidence of immunity."
