He convened a meeting of city agencies at City Hall on Thursday as a display of readiness against the spread of the deadly virus.
Representatives from the U.S. Centers for Disease Control and Prevention and the federal Department of Homeland Security also attended.
Mayor Bill De Blasio At Ebola Roundtable: NYC Is Ready
"The idea of having to be ready for something very challenging is not new to us. It's what we do as New Yorkers," de Blasio told reporters. "It's particularly what this city government does and what all our partner agencies do."
De Blasio said that the Ebola epidemic in West Africa -- which has led to cases in the United States and Spain -- has been a "painful crisis."
But he said there is "no cause for alarm" in the nation's largest city.
"This has been playing out now over weeks and weeks," the mayor said. "The planning has been going on now; it is intensifying. The important point here is that we have to understand Ebola for what it is and not make it something mysterious."
He said the city's hospital system is ready. He's urging New Yorkers to seek medical help if they feel sick.
"I can say with great confidence we have the finest health professionals anywhere in the world here in New York City, the finest health care institutions," de Blasio said, WCBS 880's Rich Lamb reported. "And that gives us tremendous strength in the face of anything we may face."
As CBS 2's Sonia Rincon reported, the mayor said anyone who thinks he or she might be suffering from Ebola symptoms should not hesitate to get care.
"I want to make crystal clear that immigration status will not be discussed," Mayor de Blasio said. "Anybody who goes to the hospital to seek emergency care because they fear that may be afflicted with Ebola will not be asked their immigration status."
The mayor said says patients will get help regardless of ability to pay.
There has not been a confirmed case of Ebola reported in New York.
As CBS 2's Jessica Schneider reported, there has only been one person in New York who showed enough symptoms to be screened for Ebola-- they tested negative.
There has been one fatality in the United States after a man, Thomas Eric Duncan, traveled from Liberia to Texas.
The sheriff's deputy who checked himself into the hospital for flu-like symptoms on Wednesday tested negative for Ebola; he had been inside the Duncan's apartment.
Mayor Bill De Blasio At Ebola Roundtable: NYC Is Ready
Trying to quell some of the fear associated with Ebola, Health Commissioner Dr. Mary Bassett stressed the virus is not easily spread -- even in public places like subways, 1010 WINS' Al Jones reported.
"This virus, although it's scary, is not easily transmitted," Bassett said. "You don't get it by walking down the street. It's not airborne."
CBS 2's Dr. Max Gomez likewise emphasized that Ebola cannot be easily transmitted like a cold or the flu.
"This anxiety is very much like the early AIDS hysteria that I covered. Like AIDS, Ebola is a virus that's not transmitted by casual contact. It requires contact with infected bodily fluids – blood, vomit or feces. Even on the subway, that's not likely to happen," Gomez said. "So do not panic, please."
But officials said the mayor and other department heads have been working through different possible scenarios when it comes to Ebola.
"We worked through four different scenarios -- talking about different things; about how we could come in contact with a potential person who has Ebola," said New York City Office of Emergency Management Commissioner Joseph Esposito.
Thursday's meeting in New York took place as new, temporary screening rules are set to go into effect at the two biggest airports in the New York area.
The new airport screening will begin Saturday at JFK International Airport and will then expand to Newark Liberty Airport next week. Additional screenings will also be added at Washington Dulles, O'Hare in Chicago and Hartsfield-Jackson in Atlanta.
The White House said checks would reach more than nine of 10 travelers to the U.S. from the outbreak zone in West Africa.
"Taking temperatures and learning more about passengers coming here from West Africa will provide another necessary line of defense against this epidemic," Sen. Charles Schumer, D-N.Y., said in a statement Wednesday. "When it comes to Ebola, you can't be too careful."
That means about 150 travelers a day will have their temperatures checked using no-touch thermometers, and health officials expect false alarms from fevers due to malaria.
Mayor De Blasio To Attend Meeting On NYC Ebola Preparedness
"We expect to see some patients with fever. That will cause some obvious and understandable concern at the airport,'' said Dr. Tom Frieden, director of the Centers for Disease Control and Prevention.
Agents will also be asking questions about the passengers' travel and potential contact with anyone who may have been infected with Ebola. If anyone shows signs of Ebola, they'll be evaluated by a quarantine officer.
Case-by-case, health workers will direct the passenger either to the local medical system or public health system for possible treatment or routine follow-ups, including daily temperature readings for the 21-day Ebola incubation period. There are quarantine areas at each of the five airports that can be used, if necessary.
The extra screening probably wouldn't have singled out Duncan when he arrived from hard-hit Liberia last month, because he had no symptoms while traveling. Duncan, the first person to be diagnosed with Ebola in the U.S., died Wednesday in Dallas.
On Thursday, Dr. Frieden compared the Ebola outbreak to the AIDS crisis and said health officials need to be diligent to make sure that this is not the world's next AIDS.
The disease has killed at least 3,800 people in West Africa with no signs of abating. On Thursday, the presidents of Liberia, Guinea and Sierra Leone, the countries hardest hit in the outbreak, are appealing to the World Bank for more help for their nations.
Ebola isn't contagious until symptoms begin, and it spreads through direct contact with the bodily fluids of patients.
Twice last month, doctors at Nassau University Medical Center thought they might have an Ebola case, WCBS 880's Peter Haskell reported.
"One was a female who had fevers, chills, coughs, high fevers and just flew in a couple days ago from Nigeria," hospital president and CEO, Victor Politi, said.
It turned out each patient didn't have Ebola, but rather malaria. In those instances, Politi said infectious disease protocols kicked in.
"What we learned is that the system in place works," he said.
Politi said they routinely have unannounced drills to make sure the hospital is ready.
Nassau University Medical Center Prepared For Ebola, Hospital President Says
President Barack Obama called the new screening measures "really just belt and suspenders'' to support protections already in place. Border Patrol agents now look for people who are obviously ill, as do flight crews, and in those cases the CDC is notified.
Speaking by teleconference with mayors and local officials, Obama said he was confident the U.S. could prevent an outbreak. But he warned them to be vigilant.
"As we saw in Dallas, we don't have a lot of margin for error,'' the president said. "If we don't follow protocols and procedures that are put in place, then we're putting folks in our communities at risk.''
Connecticut Sen. Chris Murphy told WCBS 880 Connecticut Bureau Chief Fran Schneidau it's urgent that Congress authorizes the $1 billion in funding Obama has requested to address the Ebola crisis.
"The reality is that, without almost any questions being asked, we're going to be spending $10 billion a year on this new war against ISIS in the Middle East," Murphy said. "The president is asking for one-tenth of that to try to stop a deadly disease that has already killed thousands in West Africa from coming to the United States."
Sen. Chris Murphy: Congress Should Approve Ebola Funding
At Bellevue Hospital, patients showing symptoms of Ebola are sent directly to a quarantine room where doctors and nurses wear special protective gear while tending to the patient.
The testing has been going on for two to three weeks, the city's Health and Hospitals Corp. said. Bellevue would be the default hospital for any passenger at JFK Airport who shows symptoms of Ebola.
The precautions taken inside the hospital with potential Ebola patients are all listed on a detailed checklist sent out by the CDC. Guidelines have also been handed out to first responders.
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