OMAHA, Neb. (AP) — The third American aid worker who contracted Ebola in Africa has been released from a Nebraska hospital.

Dr. Rick Sacra said he has been released from the Nebraska Medical Center at Thursday’s news conference.

The 51-year-old from Worcester, Massachusetts, began improving shortly after he arrived in Omaha on Sept. 5. He contracted Ebola while working at a hospital in Liberia.

Two other American missionaries who contracted Ebola were treated at Emory University Hospital in Atlanta, and released after recovering. A fourth American with Ebola is still being treated in Atlanta.