NEW YORK - A Doctors Without Borders physician who recently returned to New York after treating Ebola patients in West Africa has tested positive for the virus, according to preliminary test results.

He's the fourth confirmed case in the U.S. and the first in the city.

City officials say a further test by the Centers for Disease Control and Prevention will confirm the initial test.

A law enforcement official and a City official received notification of the preliminary test results and told The Associated Press on the condition of anonymity.

Craig Spencer, a 33-year-old emergency room doctor, returned from Guinea more than a week ago and reported Thursday coming down with a 103-degree fever and diarrhea.

He was rushed to Manhattan's Bellevue Hospital, a designated Ebola centre, and was being treated in a specially built isolation ward.