After a Howard County resident who had been traveling internationally recently tested positive for measles, here’s what you need to know about the highly contagious virus that now has a toehold in the state.

What happened over the weekend?

As a result of the positive test, state health officials said they are looking for people who may have been exposed to the infected person on March 5 at Washington Dulles International Airport in Northern Virginia, or March 7 at Johns Hopkins Howard County Medical Center.

The infected person was not identified, and state health officials declined to provide any additional information Monday. The person was taken to the hospital’s pediatric center, officials said. Neither state health nor hospital officials would say if the person was admitted or provide the health status.

Officials confirmed the case was not connected to the Southwest outbreak in Texas, where about 200 people have been infected. The cases in that region have spread to neighboring New Mexico, where there are approximately 30 cases. Two people have died.

What is happening now?

Officials are reaching out to people who may have come in contact with the infected patient at the hospital’s pediatric emergency department from 3:30 p.m. to 7:30 p.m. on March 7, said Tia Howard, a hospital spokeswoman.

“We recently diagnosed a patient with measles in our pediatric emergency department. The patient was immediately isolated from other patients and visitors, and out of an abundance of caution, we notified any patients and families who may have encountered the patient,” she said.

She said so far officials have not found any transmission.

State health officials also are working to notify people who may have been exposed from 4 p.m. to 9 p.m. on March 5 at Dulles, specifically in Terminal A, on transit to the main terminal and in baggage claim.

“We are enhancing our messaging on social media and doing more media interviews to spread the word on how people can protect themselves,” said Chase Cook, a spokesman for the Maryland Department of Health. “We are working closely with our colleagues in the Virginia Department of Health to monitor this situation.”

What should people be looking for and when?

Measles is highly contagious, with infectious droplets hanging in the air hours after someone with the virus coughs.

The incubation period is from 7 to 21 days, with an average of 14 days, meaning it can take an average of two weeks for someone to show symptoms. Symptoms include fever, runny nose, cough, red and watery eyes and the telltale red rash.

Officials say people who develop symptoms should call their health care provider, stay away from child care centers, schools, and work and public spaces. Unless it is an emergency, such as trouble breathing, people concerned about a possible infection should not go directly to the doctor’s office or hospital to avoid spreading the virus.

Who is most at risk in Maryland?

Maryland has a relatively high vaccination rate of about 96%, just above the 95% public health experts believe is needed for so-called herd immunity, where vulnerable people have some protection.

But there could be pockets of unvaccinated people, such as those who missed vaccines during the coronavirus pandemic. An increasing number of parents nationwide have also become skeptical of vaccines, specifically the one for measles, mumps and rubella, or the MMR vaccine, after debunked reports that it is connected to autism.

Every state requires children to be vaccinated. But many, including Maryland, have exemptions for health or religious reasons.

What about babies and pregnant women?

Babies in the United States are not typically given their first dose of vaccine until they are 12 to 15 months old, with a second dose between ages 4 and 6. Those traveling internationally can get a dose as young as 6 months, but would still need two doses later, health experts say.

Also especially vulnerable are immunocompromised people and pregnant women, who are at increased risk of complications such as pneumonia and fetal complications such as miscarriage, stillbirth, preterm delivery and low birth weight, according to the American College of Obstetricians and Gynecologists.

The group says the shots should not be administered to pregnant women, but should be given postpartum, ideally before leaving the hospital. A woman who believes she was exposed to measles should contact their health care provider.

Who else should be vaccinated?

People born after 1957 and unvaccinated, or who don’t know their vaccine status, should have one dose of the MMR vaccine, health officials say.

People who don’t know if they were ever vaccinated can do some of their own investigating, such as asking family or medical providers about their status, or searching for immunization records at home, in baby books or in school or work records, according to the U.S. Centers for Disease Control and Prevention.

Many only keep records for limited years, but state health departments such as Maryland’s do keep some records.

The CDC suggests if you can’t find your personal records, your doctor may recommend a blood test to check for immunity or another shot.