LOS ANGELES—An airline passenger infected with measles arrived at Los Angeles International Airport on the day before Thanksgiving, potentially infecting other people who were on the flight or who were in the airport terminal, public health officials said on Dec. 5.

According to the county Department of Public Health, the passenger—not a Los Angeles County resident—arrived on Qatar Airways flight QR 0739 at the Tom Bradley International Terminal B, Gate 155, on Nov. 27.

“Individuals who were at Terminal B from approximately 12:30 p.m. to 6 p.m. may be at risk of developing measles due to exposure to this traveler,” according to the Department of Public Health. “In collaboration with the [U.S. Centers for Disease Control and Prevention], passengers assigned to specific seats that may [have] been exposed on Qatar Airways flight QR 0739 on November 27th, 2024, will be notified by local departments of health. These agencies work together to investigate communicable disease exposures on international flights to the United States.”

Other people who potentially may have been exposed were urged to confirm their vaccination status or possible immunization through prior infection. Those who are not immune could be at risk of developing measles between seven and 21 days from exposure, health officials said.

“Measles spreads easily through the air and on surfaces and easily between people who are not already protected from it,” Dr. Muntu Davis, the Los Angeles County health officer, said in a statement. “A person can spread the illness to others before they have symptoms, and it can take seven to 21 days for symptoms to show up after being exposed. Measles can lead to severe disease in young children and vulnerable adults. The best way to protect yourself and your family from infection is with the highly effective [measles] vaccine.”

Common symptoms of measles include a high fever, cough, runny nose, red and watery eyes, tiny white spots inside the mouth, and a rash that develops three to five days after other signs of illness, starting at the face then spreading to the rest of the body.

According to the Department of Public Health, 280 measles cases have been reported in the United States this year, which is more than double the number from 2023, and 40 percent of the patients have required hospitalization.