An American doctor who was stricken with Ebola in Africa while helping deliver babies at a Liberian hospital has been discharged from the U.S. hospital where he had been undergoing treatment.

Blood tests on Dr. Richard Sacra taken at the Nebraska Medical Center in Omaha, where he was taken earlier in the month, confirmed he is now free of the virus.

Sacra, 51, was taken to the Nebraska facility because it possesses a biocontainment unit where patients suffering from dangerous infectious diseases can be treated.

He had been working in Liberia as a medical missionary when he became the third American to contract the deadly viral disease.

In Nebraska he was given an experimental drug called TKM-Ebola from a Canadian pharmaceutical company containing substances intended to stop the Ebola virus from reproducing.

He also received blood plasma from another American Ebola survivor, Dr. Kent Brantley, in the hope antibodies in it could help boost Sacra's immune system to fight off the dangerous virus.

The Centers for Disease Control and Prevention said two separate recent blood samples, taken a day apart, show the virus is no longer in Sacra's bloodstream.

"I am so grateful," Sacra, a family physician, said in a written statement. "Just so incredibly grateful to have gotten through this illness. Many were praying for me, even people I did not know personally."

"I feel great, except that I am extremely weak."

Sacra, from Holden, Mass., is now immune to the strain of Ebola he was infected with.

There are five Ebola strains, but a single one is behind the current outbreak in West Africa, which has affected more than 6,000 people in Guinea, Liberia, Sierra Leone, Nigeria and Senegal.

The death toll has reached 2,917 people, according to figures released by the World Health Organization.

Sacra, who spent many years living and working in Africa, said he believed he contracted the Ebola virus during deliveries and while performing Caesarean sections.

He felt lucky to have been taken to the Nebraska hospital so quickly, he said, but urged continued support for the efforts in Africa to combat the deadly disease.

"Though my crisis has reached a successful end here, unfortunately the Ebola crisis continues to burn out of control in West Africa," he said.

He wasn't ruling out the possibility of returning to work in Liberia, he added.

"When I got there in early August, women literally had nowhere to go" for help in delivering their babies, Sacra said. "The odds that I will end up back there are pretty high."