International Christian mission organization SIM missionary doctor Rick Sacra is shown in this undated photo provided by SIM on Sept 4, 2014. [Photo/Agencies]

OMAHA, Nebraska/MONROVIA - A third US health missionary infected with the deadly Ebola virus in Liberia left the West African country's capital on Thursday in a plane headed for the Nebraska Medical Center in Omaha, the Christian organization SIM USA said.

Dr. Rick Sacra, a 51-year-old Boston physician, is the latest worker for SIM USA to be infected with the virus that has killed more than 1,900 people.

The plane was expected to arrive in Omaha on Friday morning, hospital officials and SIM USA said. Sacra will begin receiving treatment in the hospital's Biocontainment Patient Care Unit, SIM USA said in a statement.

Sacra is in "reasonably stable shape. He's had a number of complications of his disease," but apparently was able to get on the plane under his own power, Dr. Phil Smith, director of the biocontainment unit, told a news briefing in Omaha.

Smith said Sacra would be given supportive care by a team of 30 to 35 people.

But he said there were no more doses of Mapp Biopharmaceutical Inc's experimental drug, ZMapp, which was given to the other two US health missionaries who had contracted Ebola. Doctors, however, said it was not clear whether the drug had contributed to their eventual recovery.

SIM USA President Bruce Johnson said Sacra had been receiving "excellent care" from the group's staff in Liberia but said the Nebraska facility would provide advanced monitoring equipment and more treatment options.

Liberian Information Minister Lewis Brown confirmed that the plane carrying Sacra was identical to the Gulfstream jet that ferried Nancy Writebol and Dr. Kent Brantly, who contracted the disease in July while working at SIM USA'S health center in Liberia, back to the United States.

The Nebraska facility is similar to the one at Emory University in Atlanta where Writebol and Brantly were treated.

Sacra volunteered to return to Liberia when Writebol and Brantly became infected.

Sacra had not been caring for Ebola patients but was delivering babies, and had been following protocols to prevent the spread of the disease, the group said. It was not known how he contracted the virus.