A measles diagnosis for a fourth person this year in Los Angeles County prompted health officials Tuesday to urge vaccination ahead of residents’ summer travel plans.
The individual had recently traveled to the county from abroad, according to the Department of Public Health.
Measles outbreaks are occurring in the United States and internationally. In the U.S. as of May 2, 935 measles cases have been reported in 2025.
Officials urged all residents to receive the measles-mumps-rubella, or MMR vaccine if they are not immune.
“Measles is a serious respiratory disease that spreads easily through the air and on surfaces, particularly among people who are not already protected from it,” county Health Officer Muntu Davis said in a statement. “A person can spread the illness to others before they have symptoms, and it can take seven to twenty-one days for symptoms to show up after exposure. Measles can lead to severe disease in young children and vulnerable adults. As LA County residents begin to travel this summer and with measles cases increasing among those who have recently traveled, we remind everyone that the best way to protect yourself and your family from infection is with the highly effective measles vaccine.”
The traveler was not infectious while in transit, officials said. Currently there are no public locations where other people may have been exposed to the measles virus, outside of health care facilities that are notifying patients and staff of the exposure. Public Health was also working to identify others who may have been exposed and attempting to confirm if those individuals have received the MMR vaccine.
The health department advised residents to review immunization and medical records to determine if they are protected against measles, especially before international or domestic travel in areas experiencing measles outbreaks.
If exposed to the virus, residents should contact and notify their health care provider as soon as possible if they are pregnant, an infant, have a weakened immune system or are unimmunized regardless of vaccination history, officials said. If symptoms develop, “stay at home, and avoid school, work and any large gatherings. Call a healthcare provider immediately. Do not enter a health care facility before calling them and making them aware of your measles exposure and symptoms.”
Airborne measles spreads easily when an infected person breathes, talks, coughs or sneezes, according to Public Health. The virus can stay in the air and on surfaces for many hours after the infected person has left an area.
“An infected person can spread the disease up to four days before a measles rash appears and up to four days after the rash appears,” the department reported. “If other people breathe the contaminated air or touch the infected surface, then touch their eyes, noses, or mouths, they can become infected.”
Symptoms include high fever above 101 degrees, cough, runny nose, red and watery eyes and a rash three to five days after other signs of illness appear. The “measles rash” usually begins on the face, then spreads downward to the rest of the body.
The MMR vaccine is administered in two doses and is more than 90% effective, officials said. Measles transmission can be prevented if two-dose coverage of vaccine remains at 95% or above in the community.
For a list of clinics that offer free or low-cost immunizations for uninsured or underinsured county residents, call 211 or visit publichealth.lacounty.gov/ip/clinics.htm.
Most of these 935 measles cases in the U.S. are linked to an ongoing measles outbreak in Texas, New Mexico and Oklahoma, Public Health reported. Most infections occurred in people who are unvaccinated or did not know their vaccination status. Three people have died from complications related to measles, and 11% of the nation’s cases required hospitalization to manage complications or for isolation.
The last measles case in an LA County resident was reported in April.
