'It's a Frightening Situation, New York is a Dense Place': Mayor

New York City: An emergency room doctor who recently returned to New York City after treating Ebola patients in West Africa has tested positive for the virus, Mayor Bill de Blasio said. It's the first case in the city and the fourth in the nation.

The mayor said on Thursday there's no reason for residents to be alarmed by the doctor's Ebola diagnosis. He said all city officials followed "clear and strong" protocols in their handling and treatment of Craig Spencer, a member of Doctors Without Borders.

"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."

"We are as ready as can be for Ebola case," he said.

Spencer, 33, had been working in Guinea. He returned more than a week ago and reported Thursday coming down with a 103-degree fever and diarrhea. He was being treated in an isolation ward at Manhattan's Bellevue Hospital, a designated Ebola center.

While addressing a press conference on Thursday evening, the mayor acknowledged, "I know it's a frightening situation. New York is a dense place," but added, "The more facts you know the less frightening it is".

"The health workers know they were prepared just for this moment. We feel good about the way we are handling the situation. We hope for the recovery of the doctor. We have the situation under control," he said.

The mayor added that health officials were in touch with four people who had contact with Ebola patient.

The Centers for Disease Control and Prevention, which will do a further test to confirm the initial results, has dispatched an Ebola response team to New York, and the city's disease detectives have been tracing the doctor's contacts to identify anyone who may be at risk. The city's health commissioner, Mary Bassett, said Spencer's fiancee and two friends had been quarantined.

City officials say Spencer acknowledged riding the subway and taking a cab to a Brooklyn bowling alley in the past week before he started showing symptoms.

His Harlem apartment was cordoned off, and his fiancee, who was not showing symptoms, was being watched in a quarantine ward at Bellevue. The Department of Health was on site across the street from the apartment building Thursday night, giving out information to area residents.