NEW YORK, Oct. 23 (UPI) —

A Doctors Without Borders physician who treated Ebola patients in West Africa tested positive for the virus Thursday, days after returning to New York City.




Dr. Craig Spencer, 33, is the first diagnosed case in the city.




Spencer has been treating Ebola patients in Guinea, and returned to New York on Oct. 14. He alerted Doctors Without Borders after he developed a 103-degree fever Thursday morning, and was subsequently rushed to Bellevue Hospital Center by emergency medical workers.




Spencer was being isolated and healthcare workers were combing the city for people he may have come in contact with. The doctor took the subway, visited a bowling alley and took a taxi home Wednesday evening. His girlfriend is healthy but being quarantined.




"Our understanding is that very few people were in direct contact with him," New York Mayor Bill de Blasio said in a statement.




Individuals infected with Ebola are not contagious until they begin to display symptoms. The virus is transmitted through bodily fluids and secretions but cannot be contracted through the air.




Ebola patient Ashoka Mukpo was declared virus-free Tuesday, and released from Nebraska Medical Center on Wednesday. Nurse Amber Vinson’s family declared she is virus-free Thursday, and nurse Nina Pham is on the road to recovery.




Meanwhile, on Wall Street, the Dow Jones industrial average got a boost from several companies’ strong earnings reports. But news of the doctor’s Ebola case brought the 300-point gain down to 216.58 points by day’s end.