WORCESTER — Dr. Richard A. Sacra, who in September was treated for Ebola virus in Nebraska and released to return home to Holden, was hospitalized Saturday at UMass Memorial Medical Center with what appears to be an upper respiratory tract infection.

Though UMass Memorial Medical Center physicians believe this illness is likely not a recurrence of Ebola, following guidance from the Centers for Disease Control and prevention, doctors at UMass Memorial Medical Center have isolated Dr. Sacra until they have confirmation of his illness, sometime within the next 36 hours.

“Dr. Sacra is in stable condition and being monitored carefully. We're waiting for final test results from the CDC, which we expect to receive late Monday,” said Dr. Robert Finberg, professor and chairman of medicine, UMass Memorial Medical Center, an infectious disease expert leading Dr. Sacra's team of doctors.

“We are isolating Dr. Sacra to be cautious pending final confirmation of his illness. We think it is highly unlikely that he has Ebola. We suspect he has an upper respiratory tract infection, with symptoms of cough and conjunctivitis,” Dr. Finberg said.

A statement from the The Nebraska Medical Center earlier Saturday said doctors do not think it likely that Dr. Sacra, who has been suffering from a persistent cough and low-grade fever for several days, has suffered a relapse of Ebola.

“Even though the likelihood of Dr. Sacra having a relapse of Ebola is extremely low, doctors will run tests to be 100 percent sure,” said Dr. Phil Smith, medical director of the Biocontainment Unit at The Nebraska Medical Center.

“Because of his recent battle with the Ebola virus, his immune system is compromised,” said Dr. Smith, who treated Dr. Sacra for Ebola. “The symptoms he has are indicative of a respiratory illness and are not those of someone suffering from Ebola.”

Earlier Saturday, UMass Memorial said a patient with a history of travel to and from West Africa was being evaluated for possible Ebola and was isolated at UMass Memorial Medical Center.

The hospital said it was working with the Centers for Disease Control and Prevention and the Massachusetts Department of Public Health and following specific plans and guidelines for the management of patients suspected to have Ebola, said Margaret Thrappas, director of marketing and interim director of media and public relations.

“We want to ensure our community that our UMass Memorial Medical Center — Memorial and University campuses — are fully operational and that the care of our patients has not been interrupted. There is no risk to our patients or to the general public.”

UMass Memorial Medical Center will issue an update on Dr. Sacra's condition on Sunday morning.

Contact Donna Boynton at Donna.Boynton@telegram.com. Craig Semon of the Telegram & Gazette staff contributed to this report.

Contact Donna Boynton at Donna.Boynton@telegram.com. Craig Semon of the Telegram & Gazette staff contributed to this report.