Oct. 28 (Bloomberg) -- U.S. health officials issued stricter guidelines that say people with direct exposure to the Ebola virus should be isolated in their homes for 21 days, stopping short of mandatory quarantines to fight the outbreak.

The U.S. Centers for Disease Control and Prevention created four risk categories and guidelines for how people should be monitored that are tighter than previous rules, said Tom Frieden, director of the CDC. The rules apply to health workers returning from fighting the outbreak in West Africa and for anyone in contact with Ebola patients in the U.S.

After a New York doctor was diagnosed with the Ebola virus last week, governors Andrew Cuomo of New York and Chris Christie of New Jersey announced policies requiring 21-day quarantines for anyone returning from a country with an Ebola outbreak who may have had contact with patients. The White House and infection control specialists said those policies aren’t based on science and will discourage aid workers from volunteering to fight the outbreak, which has infected about 10,000 people in Liberia, Guinea and Sierra Leone.

“We’re engaging in a series of discussions with state and local health departments,” Frieden said yesterday in a telephone call with reporters. “If they wish to be more stringent than what CDC recommends, that’s within their authority.”

Staying Firm

Christie said he won’t rethink New Jersey’s policy even after facing criticism over the case of nurse Kaci Hickox, who he ordered confined to a hospital before releasing her to Maine. Other states and the military have taken the same position as his, he said today on NBC’s Today show.

“The CDC has been behind on this,” Christie said. “Folks got infected in Texas because they were behind and we’re not going to have folks being infected in New Jersey and other states in this country.”

The first U.S.-diagnosed case of the virus occurred in Dallas late last month. The patient, Thomas Eric Duncan, died Oct. 8 at Texas Health Presbyterian Hospital and infected two nurses who were part of the medical team treating him.

U.S. Army personnel who return to their home bases after working near the outbreak in West Africa will be isolated and monitored for 21 days as a precaution, the Pentagon announced yesterday. About 700 U.S. military personnel are deployed to West Africa, including almost 600 in Liberia, with the remainder in Senegal, according to the Pentagon.

Four Categories

The CDC guidelines break people down into four categories. Those considered highest risk would be isolated in their homes for 21 days. People like the New York doctor, as well as a nurse who was quarantined under New Jersey’s policy, would be monitored closely, though not isolated automatically.

The highest-risk group includes people with possible direct exposure to the virus, either through direct contact with a patient or with someone else who had contact with an infected person. These people would be told to stay at home and keep away from public places and transportation, Frieden said.

“Health-care workers, of all people, understand that if they develop Ebola, the sooner they get care the more likely they are to survive, and the sooner they’re isolated the less likely they are to infect their family members,” Frieden said.

People who have cared for Ebola patients in an outbreak area and who are not known to have been exposed are considered at some risk, Frieden said. These people should be “intensively monitored,” and contacted daily for 21 days after their arrival by state and local health, he said. Their travel may also be restricted on a case-by-case basis, he said.

Low Risk

Health workers taking care of Ebola patients in the U.S. would be considered at low risk. People who have never traveled to an Ebola outbreak area, or who haven’t done so for 21 days, would be considered no-risk, he said.

Fewer than 100 people a day enter the U.S. after traveling in the West African outbreak countries, Frieden said. In total, 807 people arriving in the U.S. have been screened since Oct. 11 and 46 of those have a background in health work, he said.

New York and New Jersey issued the quarantine orders after the New York doctor, Craig Spencer, was hospitalized with Ebola. Spencer was a volunteer with Doctors Without Borders who cared for patients in Guinea. He returned to New York, and soon before being driven to the hospital with Ebola symptoms had taken the New York City subway, eaten at a meatball restaurant and visited a bowling alley.

Too Cautious?

“The federal government doesn’t agree with our policy,” Cuomo said in Mineola, New York, yesterday before Frieden released the guidelines. “The CDC thinks we’re being too cautious.”

“State and local officials have broad authority to impose quarantine policies in their own states and localities,” White House press secretary Josh Earnest said yesterday in a briefing with reporters. “The role for the CDC is to marshal scientific evidence.”

Georgia Governor Nathan Deal said that his state will increase monitoring of inbound travelers from the affected countries. Passengers showing no symptoms but deemed high-risk because of known direct exposure to an Ebola patient will be subject to quarantine at a designated facility, Deal said.

Those deemed low risk will sign monitoring agreements with the state health department, requiring them to report their temperatures daily to the state. Medical personnel who were treating Ebola patients will be issued a 21-day active monitoring order and will be visually monitored twice daily by the health department, either in person or by videoconference. Those who do not comply will be quarantined, Deal said.

Doctors Without Borders voiced opposition to the state quarantine orders for non-symptomatic health-care workers, saying they “could undermine efforts to curb the epidemic at its source.” The Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, and the Association for Professionals in Infection Control and Epidemiology have also condemned the policies.

To contact the reporter on this story: John Lauerman in Boston at jlauerman@bloomberg.net

To contact the editors responsible for this story: Reg Gale at rgale5@bloomberg.net Drew Armstrong, Andrew Pollack