Dr. Craig Spencer, the Ebola patient being treated at Bellevue Hospital in New York, followed all recommended procedures after he arrived home from working with Doctors Without Borders in Guinea. But American health authorities are gearing up for even stronger regulations starting on Monday.

Dr. Spencer is the fourth person diagnosed with the disease in the United States. There have been more than 9,900 cases and 4,800 deaths in West Africa.

Many New Yorkers were concerned when they learned that Spencer, 33, rode on the subway and went to a bowling alley in Brooklyn on Wednesday, before he felt symptoms and checked into the hospital on Thursday. But experts say Spencer followed protocol.

“He did everything right,” said Dan Epstein, a World Health Organization spokesperson. “Once he noticed the symptoms he isolated himself, called in and was taken to a hospital designated for that.”

Doctors Without Borders has a set of specific guidelines for all staff members returning from Ebola-affected countries, based on recommendations from the U.S. Centers for Disease Control and Prevention, which include the following instructions:

  1. Check temperature two times per day.
  2. Finish regular course of malaria prophylaxis (malaria symptoms can mimic Ebola symptoms).
  3. Be aware of relevant symptoms such as fever.
  4. Stay within four hours of a hospital with isolation facilities.
  5. Immediately contact the MSF-USA office if any relevant symptoms develop.

“Our colleague in New York followed the MSF [Médecins Sans Frontières, or Doctors Without Borders] protocols and guidelines since returning from West Africa,” the organization said in a Friday press release, explaining that Spencer immediately notified MSF when he detected a fever, and stayed in his apartment before Bellevue Hospital staff picked him up.

The organization’s statement emphasized that “family, friends and neighbors can be assured that a returned staff person who does not present symptoms is not contagious and does not put them at risk.”

“There is no cause for alarm,” New York City Mayor Bill de Blasio assured the public at a Friday press conference.

If a patient doesn’t live within four hours of an appropriate facility, MSF will pay for their accommodation during the 21-day period. It also pays for their volunteers to take the time off work.

A day before news broke about Spencer’s diagnosis, the CDC announced that even stronger measures would be put in place by state and local officials to monitor people returning from the region.

In a Wednesday statement, the agency said it would begin “active post-arrival monitoring” of all travelers from Guinea, Liberia and Sierra Leone, which requires they keep in contact with public authorities on a daily basis for 21 days after their last possible date of exposure to Ebola.

“Post-arrival monitoring is an added safeguard that complements the existing exit screening protocols,” the CDC said.

Returning travelers will have to report to public officials daily about whether they have Ebola symptoms and inform them of any upcoming travel plans. If they do present a risk, authorities will “implement an isolation and evacuation plan,” to get the patient safely to a hospital.

Incoming travelers will also receive a special kit at the airport that includes a thermometer, information and contact numbers for health authorities.

The CDC said New York, Pennsylvania, Maryland, Virginia, New Jersey and Georgia, which receive roughly 70 percent of all incoming travelers, have already “taken steps” to plan their post-arrival monitoring, which will take effect on Monday.