An American surgeon who contracted Ebola while working in eastern Democratic Republic of the Congo was flown to Germany for treatment Tuesday after his condition deteriorated significantly, according to leaders of the Christian missionary organization where he served.

Scott Myhre, East and Central Africa area director for the missionary group Serge, described the condition of Dr. Peter Stafford as he departed Congo.

“There were people in full PPE — personal protective equipment — completely covered, and he was hanging onto them, barely strong enough to walk,” Myhre said. “He looked really tired and really sick.”

Stafford had been working at Nyankunde Hospital in Congo’s Ituri Province, the center of the country’s current Ebola outbreak.

According to Myhre, Stafford treated a 33-year-old patient suffering from severe abdominal pain shortly before the outbreak was officially confirmed by the Africa Centres for Disease Control and Prevention.

Doctors initially believed the patient was suffering from a gallbladder infection.

“Dr. Stafford performed an abdominal procedure and found the gallbladder was normal,” Myhre said. “The patient later died the following day.”

The patient was buried before Ebola testing could be conducted, but medical teams later concluded the individual likely died from the virus.

Stafford began developing symptoms over the weekend and tested positive for Ebola on Sunday, according to the Centers for Disease Control and Prevention.

Health officials continue monitoring the outbreak, which has already triggered international concern as cases spread across eastern Congo.