Nurses wait for patients at the Rockland County Health Department in Haverstraw, N.Y., which has been affected by the measles outbreak. (Johannes Eisele/AFP/Getty Images)

A case of measles confirmed in Maryland last week appears not to have spread into the greater Washington area, officials said Thursday, but government health agencies are preparing and watching for any additional signs of the highly infectious disease.

From Jan. 1 to April 4, 465 measles cases were confirmed in 19 U.S. states, the federal Centers for Disease Control and Prevention reported. One of those was a child in Pikes­ville, Md., northwest of Baltimore.

In response, Sinai Hospital is asking visitors under age 14 to avoid its northwest Baltimore campus unless they have an appointment, the Baltimore Sun recently reported.

Measles easily spreads through sneezes and coughs and can live on some surfaces for up to two hours after contamination. The disease is transmitted when people who have not been vaccinated come into contact with others, so areas around international airports or proximity to communities who shun vaccines are of particular concern.

The last local outbreak, in 2015, stemmed from an unvaccinated traveler who arrived at Washington Dulles International Airport and spread the infection from there.

“With the number of cases in the country right now, I’d be surprised if we don’t eventually get some,” said Shawn Kiernan, senior epidemiologist with Fairfax County’s communicative diseases division.

Mary Anderson, a spokeswoman for Montgomery County’s Health and Human Services Department, noted that in the Washington region, it is easy to find people who live in one state, travel to work in the other and then stop in Washington to eat or shop.

“So far, we’ve been spared the outbreak,” Anderson said. “But our immunization rates are generally high — we’re not known as a pocket of anti-vaccination sentiment.”

However, state health officials said they are carefully watching the disease as it races through parts of the Northeast, the West Coast and the interior of the country. New York City declared a public health emergency this week and made immunization mandatory in some communities.

Colleges in the D.C. area said they have had no instances of measles infections, but the University of Maryland sent out a campuswide notice Wednesday reminding students and employees that a “measles vaccine is required for students at UMD.”

The notice said the university was “working to alert those students who have not submitted proper records.”

When a case is reported, Kiernan said, public health departments work together to confirm it is measles and then interview the patient to determine where they have traveled while infectious.

The patient is kept isolated, usually voluntarily, and health officials develop exposure lists. For example, if he or she went to a large office building with a single ventilation system, everyone in that building would be notified that they have been exposed.

Individual people who may have come into contact with the patient are sought out and warned that the symptoms of measles can mimic other diseases — with high fever, cough, red runny nose and watery eyes — before the appearance of white spots in the mouth and eventually red spots on the skin.

‘If we catch people early enough, we can give them medication,” Kiernan said.

Vaccines will work if given within three days of exposure, and immunoglobulin can work within six days of exposure. But that’s an expensive treatment route that doesn’t protect everyone, he said.

The good news is that if someone was vaccinated as a child, the prevention lasts a lifetime.