An American doctor being treated for Ebola in Germany says he is beginning to feel hopeful about his recovery despite experiencing more severe symptoms of the disease.

Dr. Peter Stafford contracted Ebola while caring for patients in the Democratic Republic of the Congo and was later evacuated to Germany for specialized medical treatment.

Stafford is currently hospitalized at Charité University Hospital in Berlin.

“Before I was evacuated I was feeling really concerned I wasn’t going to make it, and now I’m cautiously optimistic,” Stafford said in a statement released by Serge, the international missionary group that employs him.

Scott Myhre, Serge’s East and Central Africa area director, said Stafford remains critically ill but has shown signs of improvement compared with earlier in the week.

According to Myhre, Stafford is now able to eat small amounts of food.

Doctors said Stafford initially experienced what are commonly known as “dry” Ebola symptoms, including fever, body aches and extreme fatigue.

He has since developed more advanced “wet” symptoms associated with the disease, including vomiting and diarrhea.

Despite the worsening symptoms, Myhre said Stafford’s laboratory results are “trending slightly in the right direction,” offering cautious encouragement about his condition.