John Goldman had not seen a case of measles in 30 years. But since April, the infectious disease specialist with the University of Pittsburgh Medical Center in central Pennsylvania has had dozens of patients come down with the disease.

“I never thought I would see this come back,” he says.

His health system, like others, has had to adapt to a new normal as measles makes a comeback in the United States. As the country’s cases top 3,600, the highest yearly total since 1991, hospitals and health care providers are being forced to dust off decades-old protocols or develop new ones to deal with the highly contagious disease.

The University of Pittsburgh Medical Center’s community hospital in Lititz is in Lancaster County, the center of Pennsylvania’s current outbreak. It has evaluated around 50 patients with measles, with roughly 20 of those requiring hospitalization. Statewide, Pennsylvania has recorded 943 cases, including 176 hospitalizations and five measles-related deaths as of September 30.

Goldman says the Lititz hospital has rapidly ramped up measles screening, asking patients if they are experiencing symptoms such as fever, cough, sore throat, red eyes, and whether they are vaccinated. The classic measles rash does not appear until three to five days after these cold-like symptoms begin, or about one to two weeks after exposure to the virus.

The hospital is instructing physicians to call ahead before referring a patient with suspected measles to the emergency department. Patients must wear a mask and wait in the parking lot, where a staff member meets them and escorts them directly to a negative-pressure room, bypassing the waiting area. These special isolation spaces have lower air pressure than outside hallways, which traps airborne pathogens inside and prevents them from spreading within a hospital. Patients who don’t have serious symptoms are asked to stay at home.

“We are really trying to prevent people from coming to the hospital with measles, because once they’re in the hospital, it’s very easy for them to expose other people,” Goldman says.

Jennifer Janco, chair of pediatrics for St. Luke’s University Health Network, which serves eastern Pennsylvania and New Jersey, says that with falling vaccination rates and increasing measles cases around the country, “it was only a matter of time before we started seeing cases.”

St. Luke’s treated two unvaccinated siblings for measles in late July. One of the siblings was hospitalized in a different health network but released, and both were able to recover at home while pediatricians oversaw their care remotely. The health network has also tested other patients suspected of having measles.