(CNN) A man in Sweden who was being treated for suspected Ebola contamination at Uppsala University Hospital on Friday does not have the deadly virus.

"We have run several tests for the Ebola virus and other viruses and they have been negative," said Mikael Köhler, the chief medical officer of the hospital. He added that the patient "has become much better and stable and not bleeding anymore."

The patient, who is in isolation, was admitted to a hospital in Enköping -- about 50 miles (80 kilometers) from Stockholm -- before being transferred to Uppsala about 7 a.m. local time, according to the regional authority.

The man was in Burundi for about three weeks and returned to Sweden three weeks ago, Köhler said Friday.

He visited "mostly urban areas in Burundi, where there isn't thought to be any active Ebola as far as we know," Köhler said.

But the patient displayed potential symptoms of Ebola, including vomiting blood, upon arrival at the hospital, he explained.

Authorities said the emergency room at Enköping has closed, and staff members who were in contact with the patient are being looked after.

"We have to take the precautions due to several patients and staff becoming exposed to it," Köhler said after Ebola was eliminated as a diagnosis.

A door of the hospital in Enköping, Sweden. The emergency room there has was closed, and staff who came into contact with the patient are being cared for.

Ebola -- which causes fever, severe headaches and in some cases hemorrhaging -- kills about half of those infected.

Cases of Ebola are very rare in Europe, with one case reported in Italy in 2015, one in Spain in 2014 and one in the UK the same year, according to the World Health Organization.

University of Nebraska Medical Center in Omaha is monitoring an American who was possibly exposed to Ebola while providing medical assistance in Democratic Republic of Congo. Dr. Ted Cieslak, an infectious disease specialist at the medical center, said in a statement on December 29, "the person may have been exposed to the virus but is not ill and is not contagious."

Burundi borders Congo, which is going through the second-deadliest and second-largest Ebola outbreak in history -- with cases surpassing 600 as of Wednesday. This is topped only by an outbreak in West Africa in 2014 when the disease killed more than 11,000 people, according to WHO.

Humans can become infected by Ebola if they come into contact with fluids such as blood, urine and tears from an infected person or objects contaminated by an infected person. The virus is not transmitted through the air.

Humans can also be exposed to the virus through infected animals, for example, by butchering them.

Health care workers who are unprotected are susceptible to infection because of how closely they work with patients.