A Howard County resident who recently traveled abroad tested positive for the highly contagious virus measles, the Maryland Department of Health said Sunday.

“Out of an abundance of caution,” state and local public health officials are working to identify anyone who might also have been exposed, the Maryland Department of Health said in a news release.

According to the department, individuals who visited Washington Dulles International Airport in Virginia from 4 p.m. to 9 p.m. on Wednesday or Johns Hopkins Howard County Medical Center pediatric emergency department from 3:30 p.m. to 7:30 p.m. on Friday may have been exposed.

Exposure risk at Dulles was likely confined to Terminal A, on transit to the main terminal and in baggage claim.

Officials encourage anyone who was at these locations in the potential exposure windows to monitor for fever and other symptoms such as runny nose, cough, red and watery eyes, and a red rash. Individuals who develop symptoms should call their health provider and stay away from child care centers, schools, work or public places.

On a call with reporters Sunday afternoon, Health Department officials declined to provide details about the Howard County individual, who checked into a pediatric center Friday, or to disclose the person’s vaccination status.

But Lucia Donatelli, chief of the health department’s Center for Immunization, Infectious Disease Epidemiology and Outbreak Response Bureau, stressed that vaccination is by far the best defense against the virus.

Measles is so contagious that people can become infected by walking through the same space hours after an infected person coughed, health experts say. One in five people may become hospitalized. Many patients suffer long-term complications.

Measles cases have cropped up in Maryland from time to time — one individual was identified with the virus in the state last year and another in 2023, according to the health department.

But a growing outbreak in the Southwestern U.S., along with the country’s first death from the virus in a decade in Texas, has alarmed Maryland public health experts, who worry about the possibility of nationwide spread. A second person died with the virus in New Mexico.

Officials with the Maryland Department of Health said the Howard County case is not associated with the Southwest outbreak, which Donatelli said has taken off in an under-vaccinated region of West Texas, where close to one in five kindergartners opted out of the measles, mumps and rubella vaccine.

Vaccination rates in Maryland are much stronger, though Donatelli said the state has its own under-vaccinated “pockets.”

As of Friday, more than 200 people had contracted measles in Texas and another 30 in New Mexico, according to The Associated Press, a historic outbreak of the virus.

An unvaccinated child died from the virus in Texas, while an unvaccinated adult died Thursday in New Mexico after testing positive for the virus, a death officials there say was at least “measles-related.”

Compounding the challenge for public health officials, Robert F. Kennedy Jr., the new U.S. health and human services secretary, has played down the Texas measles outbreak and has been critical of vaccines generally for years. He has backed the widely debunked theory that the MMR vaccine causes autism in children.

Considered eliminated in the United States in 2000, measles cases persisted among people who had traveled to countries where it has been more prevalent.

All 50 states require school-age children to be vaccinated, with religious and medical exemptions in many states, including Maryland. But national rates dropped during the pandemic below the 95% threshold — the level considered necessary for the broad community protection known as herd immunity.

Once an individual contracts measles, a red rash typically appears one to four days after other early symptoms, starting on the face and spreading to the rest of the body.

Symptoms tend to develop 10 to 14 days after exposure, according to the health department, though they sometimes show as early as seven days after or as late as three weeks after.

An infected individual is considered contagious before the measles rash is visible. A person with measles becomes contagious four days before the rash appears and for another four days after it begins, according to the health department.

Pregnant women, infants under a year old and immune-compromised individuals are thought to be most at risk of complications from measles.

Health experts generally consider people immune to measles if they have had two vaccines against the virus, if they have previously contracted measles or if they were born in the United States before 1957.

The health department is urging anyone in at-risk groups who might have been exposed to the virus to contact their health care provider or seek guidance from the Howard County Health Department’s Infectious Disease Surveillance and Response Program by calling 410-313-6284.

They also say that symptomatic individuals should refrain from showing up to emergency departments or waiting rooms until after speaking with their health provider to avoid spreading the virus to other patients.