ATLANTA (CNN) — Doctors at Emory University Hospital are treating a patient with Lassa fever.

The patient, an American physician assistant who was working with a missionary organization in West Africa, arrived Saturday. Health officials said the person had contact with or cared for a Lassa fever patient at a hospital in Togo.

A CDC spokesperson said its lab confirmed the Lassa fever diagnosis.

Doctors are treating the patient in the hospital’s Serious Communicable Diseases Unit, an isolation unit in which they successfully treated four Ebola patients. There have only been a few cases in the United States.

“We felt this way when we took care of the patients in 2014 and 2015 with Ebola virus,” said Dr. Colleen Kraft, one of the infectious diseases doctors treating the patient. “We read a lot of book chapters, we read a lot of information online with the Centers for Disease Control and Prevention, online from people who have published research papers.”

There are an estimated 100,000 to 300,000 cases of Lassa fever in West Africa every year, with about 5,000 resulting in death. It is primarily spread by rats. People can also get it from direct contact with an infected person’s bodily fluids.

While Ebola and Lassa fever can result in similar symptoms, doctors say Lassa fever is not as severe and not as deadly as Ebola.

“We don’t have as much information as we might if Lassa fever was a recurring illness in the United States,” said Kraft.

“In general we treat patients that enter the hospital almost the same, we evaluate them, we assess them,” she said. “We then decide on a course of treatment based on what we find.”

Kraft said doctors and nurses gained valuable experience when the Ebola patients were at Emory and added they take every precaution in the isolation unit, including working with a partner.

“We also watch each other as we put on and take off this high level personal protective equipment,” she explained.

Doctors don’t know how long the patient will be at Emory University Hospital.

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