U.S. doctor tests positive for Ebola in Liberia: aid group

An American missionary doctor working in Liberia has tested positive for the Ebola virus, his organization SIM USA said Tuesday.

The doctor was treating obstetrics patients at ELWA hospital in Monrovia, capital of Liberia and had not treated Ebola patients in the hospital's Ebola isolation unit, a facility separate from the main hospital, the organization said in a statement.

It is not yet known how the doctor contracted the virus specifically.

"Upon onset of the symptoms, the doctor immediately isolated himself and has since been transferred to the ELWA Ebola isolation unit," SIM USA said. "The doctor is doing well and is in good spirits."

The news came about two weeks after Nancy Writebol, who also worked for SIM USA, and her colleague Kent Brantly, were released from a hospital in Atlanta. The two contracted the Ebola virus in July while treating patients in Liberia and were later evacuated to the U.S. for treatment.