New York City officials Thursday night urged the public to remain calm after a local doctor tested positive for the often-deadly Ebola virus, which he contracted while treating patients in an epidemic-afflicted West African country.

But as officials emphasized how difficult it was to transmit Ebola to others, they also revealed that the infected physician, Dr. Craig Spencer, has had potential contact with four other people including his fiance, rode the city subways and went for a three mile jog in the week since he's been back in New York.

Spencer, 33, also had strolled along a popular Manhattan tourist destination, the High Line elevated walkway, and on Wednesday night went bowling at an alley in the trendy Williamsburg area of Brooklyn, which has temporarily closed as a result. And he may have visited a restaurant, officials said.

Spencer's fiancee and two friends are being quarantined because of contact with him. They so far are healthy, with no symptoms of Ebola, officials said. An Uber driver whose car Spencer rode in is not considered at risk because the two had no physical contact.

"There's no reason for New Yorkers to be alarmed," said Mayor Bill de Blasio. "Ebola is definitely a hard disease to contract."

De Blasio noted the disease is transmitted when a patient is symptomatic, and only through contact with bodily fluids, not through the air.



Spencer only developed symptoms of Ebola on Thursday morning, when the upper Manhattan resident started running a fever that hit 103 degrees, officials said.

Soon after, Spencer was taken to Bellevue Hospital—which was recently designated as the treatment facility for any Ebola patients in the city, and where he is now in isolation.

"We look forward to a quick recovery for him," said Dr. Howard Zucker, the state's acting health commissioner.



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Before Thursday, Spencer was feeling healthy—although he developed slight fatigue a few days before Thursday, officials said.



Since his return from the African nation of Guinea, where he had worked with the international aid group Doctors Without Borders, Spencer had not gone to his job at the prestigious Columbia University-New York Presbyterian Hospital. Officials said he had been mindful of his risk of exposure, and therefore minimized contact with others and was taking his temperature twice a day.

An Obama Administration official said several members of a rapid response team from the Centers for Disease Control and Prevention will arrive in New York tonight, and others will be there in the morning. Officials expect to have a confirmatory test on Spencer's blood completed by the CDC on Friday.



Financial markets impact

Financial markets reacted quickly to the news, with Dow futures falling 71 points and US 10-year Treasury yields falling to 2.2517 percent. US stocks gave up about a third of their rally in late trading Thursday after word of the potential case first broke. (Click here for the latest on U.S. futures)

Some New Yorkers had a blase reaction to the news.

"I am worried—and not," said Jerry Peetus, who works at a Duane Reade pharmacy near Times Square in Manhattan. "Once I say my prayers, I'll just leave it in the hands of God."



Spencer is the fourth person ever to be diagnosed in the U.S., and the first to be diagnosed outside of Dallas, which has three confirmed Ebola cases to date. He is also the first person to have worked with Doctors Without Borders, out of more than 700 so far during this outbreak, to develop confirmed Ebola symptoms after returning to their home country, the group said.

During a press conference Thursday night, de Blasio and Gov. Andrew Cuomo repeatedly said authorities had quickly responded to the first indication that Spencer had fallen ill, and urged people not to panic.

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"We've been preparing for months for the threat caused by Ebola," de Blasio said. "We have clear and strong protocols which are being scrupulously followed."



Cuomo said, "I know its a frightening situation ... New York is a dense place, a lot of people on top of each other, but the more facts you know, the less frightening the situation is."

New York was prepared to deal with an Ebola patient after a mini-outbreak in Dallas in recent weeks led to the death of one man, who contracted the virus in his native Liberia, and then infected two nurses who treated him in Dallas, the governor said.

"The past few weeks we've been preparing for just this circumstance. We were hoping that it didn't happen. But we were working literally night and day to coordinate state and federal response," Cuomo said. "We are as ready as one could be for this circumstance."

City Health Commissioner Dr. Mary Travis Bassett Spencer said she saw "no reason" why other tenants in the apartment building where Spencer lived should "be concerned" about being exposed to Ebola.

Bassett said Spencer in the past week had ridden the A subway line, which passes closes to his Hamilton Heights residence, as well as the L and the 1 lines. But she added that that was not necessarily a health concern for other members of the public.

"At the time the doctor was on the subway he had not had fever, he had no problem with his body fluids," Bassett said. "He was not symptomatic at that time, he had no fever, so he did not have a stage of disease that creates a risk of contagiousness on the subway."

"The probability being close to nil that there would be any problem related to his taking the subway system," she added.