The doctor who became the first person diagnosed with Ebola in New York City had been monitoring his health since returning from West Africa. 

Mayor Bill de Blasio says that Dr. Craig Spencer had been checking his temperature twice daily and felt perfectly fine until Thursday, when he registered a slight fever at 100.3. 

According to health officials, Oct. 12 was the last time that Spencer had any contact with Ebola patients overseas. He then arrived back home at John F. Kennedy International Airport on Oct. 17 and reported feeling only fatigue on Oct. 21. 

The 33-year-old immediately called Doctors Without Borders when he noticed the temperature increase. He was quickly taken to Bellevue Hospital and put into isolation, where he is said to be in stable condition. 

Prior to his diagnosis, Spencer ate at a Meatball Shop on Greenwich Street in Manhattan. He also visited Blue Bottle Coffee on the High Line and The Gutter bowling alley in Brooklyn, both of which have already been cleared. Spencer took the A train and the L train to the bowling alley, both trains have also been given the all clear.