Dr. Craig Spencer reported symptoms for the deadly virus on Thursday morning, nearly a week after returning from Guinea where he worked at an Ebola treatment center. The 33-year-old became the fourth person diagnosed with the disease in the US and the first in its largest city.

According to health officials, initial reports were incorrect when they showed that the doctor had a 103-degree fever when he informed authorities about his ill health. He actually only had a 100.3 fever.

Officials said that Dr. Spencer, a physician for the humanitarian group Doctors Without Borders, was in stable condition on Friday, adding that 3 people who had close contact with the doctor were quarantined for observation.

The news of the city’s first Ebola case sent US equities markets lower on Thursday afternoon and Friday morning. US stocks edged lower in early trade Friday.

About half an hour into trade, the Dow Jones Industrial Average stood at 16,668,56, down 9.34 points (0.06 percent).

The S&P 500 dipped 2.94 (0.15 percent) to 1,947.88, while the Nasdaq Composite Index slipped 3.16 (0.07 percent) to 4,449.63

New York City Mayor Bill de Blasio and Gov. Andrew Cuomo on Thursday urged residents not to panic by the first case of Ebola in their city.

"We want to state at the outset that New Yorkers have no reason to be alarmed," de Blasio said. "New Yorkers who have not been exposed are not at all at risk."

The mayor tried to reassure the public that “clear and strong” protocols were being followed to handle and treat the infected doctor.

The city’s health officials have been retracing Spencer's steps to identify anyone who might be at risk.

So far, four people have been isolated because of potential exposure, three of whom are being quarantined.

The Centers for Disease Control and Prevention (CDC) has also dispatched an Ebola response team to New York.

The latest epidemic has killed 4,877 people around the world, while more than 9,936 people have been infected, the World Health Organization (WHO) said on Wednesday.