An American doctor who contracted Ebola while working in Democratic Republic of the Congo is beginning to recover after being transferred to Germany for treatment, according to a colleague.

Dr. Peter Stafford is currently receiving care at Charité University Hospital in Berlin after testing positive for Ebola linked to his medical work in Congo.

Matt Allison, executive director of the Christian missionary organization Serge, said Stafford has been treated with monoclonal antibody therapy during his hospitalization.

According to Allison, Stafford’s condition has improved noticeably since arriving in Germany, and the doctor has been able to communicate with colleagues through text messages.

“He needed assistance to walk. He was very weak. He was discouraged,” Allison said. “He was talking about almost being unable to think.”

Allison said the combination of isolation, uncertainty and severe illness had taken a heavy emotional and physical toll on Stafford.

“I’m so glad that he’s responding quickly,” Allison added.

He also said Stafford is now able to eat again, which doctors view as an encouraging sign given the gastrointestinal symptoms commonly associated with Ebola.

“He feels good. He’s eating,” Allison said. “One of the symptoms of Ebola is nausea and gastrointestinal issues, so we’re really grateful he’s able to eat now and encouraged by where he’s at.”

Stafford, a 39-year-old board-certified general surgeon specializing in burn care, contracted the virus after treating patients in Bunia before health officials formally identified the Ebola outbreak in the region.