A Massachusetts doctor and missionary who was successfully treated for Ebola he contracted in Africa is back in the hospital with what appears to be a respiratory infection, but doctors don’t suspect a recurrence of the virus.

UMass Memorial Medical Center said in a statement that Dr. Richard Sacra was hospitalized Saturday and is in stable condition. He has a cough and conjunctivitis, commonly known as pinkeye, hospital officials said.

Sacra will remain in isolation until doctors have confirmation from tests by the U.S. Centers for Disease Control and Prevention that he is not infected with the virus, the hospital said. Doctors expect to know with certainty by late Monday.