OMAHA, Neb. >> The Nebraska doctors treating the man who became infected with Ebola while working in Liberia said Sunday that he is making progress, but it’s not yet clear if he will recover.

Dr. Rick Sacra, 51, arrived at the Nebraska Medical Center on Friday for treatment in the hospital’s specialized isolation unit. Sacra remains very tired and stable, but was more alert Sunday, said Dr. Phil Smith, one of the doctors treating him who gave an update Sunday.

“We are encouraged by what we see, but it’s too early to say he has turned a corner,” Smith said.

Sacra has been helping with his own treatment by providing information about Ebola to the doctors because he saw it in Africa.

The doctor from Worcester, Massachusetts, spent about 15 years practicing family medicine at a hospital in Liberia with the North Carolina-based charity SIM. Two other Americans have also become ill with Ebola while helping people suffering from the disease.

In West Africa, roughly 2,100 people have died during the outbreak, but Ebola has not been confirmed as the cause for all of the deaths. Sacra’s wife, Debbie, said in a statement Saturday that she hopes the world will focus on the larger Ebola outbreak, not just her husband’s illness.

The doctors said Sacra has joked with them about baseball because he is a Boston Red Sox fan and Smith follows the New York Yankees.

“He’s made a few jokes,” Smith said. “In my experience, that’s a good sign.”

Smith said Sacra is receiving an experimental drug that is different than the one given to the two earlier American Ebola patients.

Sacra was able to visit with family members and friends for about half an hour on Saturday and Sunday via a video conference system at the hospital. Dr. Angela Hewlett said family members read Bible verses to him.