Liz Szabo

USA TODAY

New guidelines from the Obama administration would restrict the movement of people at high risk of Ebola but would not require mandatory quarantines.

The guidelines, issued by the Centers for Disease Control and Prevention on Monday, individualize recommendations for travelers based on a person's level of risk.

The issue of how to monitor travelers from West Africa -- and other contacts of Ebola patients -- became a matter of national debate Thursday when a New York physician was diagnosed with the disease after working with Doctors Without Borders in Guinea. The doctor, Craig Spencer, had not treated patients since his return but had ridden the subway, gone bowling and gone to a restaurant. He is being treated at Bellevue Hospital Center in New York.

The governors of New York and New Jersey issued mandatory quarantine policies, and a 33-year-old nurse with Doctors Without Borders was quarantined in a New Jersey hospital over the weekend. Gov. Chris Christie, a Republican, subsequently said she could go to her home in Maine.

New York Gov. Andrew Cuomo, a Democrat, said people at risk of Ebola could stay in their homes for 21 days, the incubation period for Ebola, rather than in special facilities.

The nurse, Kaci Hickox, was released Monday and allowed to travel to her home state of Maine.

The CDC guidelines sort people into four categories -- "high risk," "some risk," "low risk" and "no risk" -- based on their level of exposure to Ebola patients:

People at high risk include health care workers who, for example, accidentally stick themselves with a syringe while treating an Ebola patient and family members who cared for an Ebola patient at home without proper protective equipment, a common practice in West Africa. Those people would be told not to use public transportation for 21 days and could be included on a "Do Not Board" list for air travel, said CDC director Thomas Frieden. They would be told not to go to work outside the home. While those people would be allowed to leave their homes to, say, jog in a public park, they would not be allowed to attend "congregate gatherings" such as baseball games.

People who fall into the category of "some risk" for Ebola -- such as a health care professional who works in an Ebola treatment center in Africa but who consistently wears protective clothing -- should be actively monitored by local health officials, with their temperatures taken twice a day, Frieden said. Local officials can decide whether to restict their travel.

Those at "low risk" include people who have traveled to an Ebola-stricken country but who have had no contact with Ebola patients, Frieden said. The guidelines say those people should monitor their temperature and symptoms, but their travel is not restricted.

Although the CDC doesn't have the authority to enforce the guidelines, "we find that state and local health departments usually do follow CDC guidelines," Frieden said. He said that states and local governments will most likely develop their own policies.

States don't need to be overly restrictive, Frieden said, because nearly 40 years of experience with Ebola in Africa has shown that people are not infectious until they develop symptoms, such as a fever. Anyone at risk of Ebola who develops a fever should immediately contact the health department monitoring them, he said.

A study of Ebola caregivers in Africa found that it is not highly contagious in the early stages and doesn't spread through casual contact, Frieden said. Among family caregivers who lived with Ebola patients and took care of them, for example, only 16% became infected. Among people who shared a household with an Ebola sufferer but didn't provide direct care, none of the 76 people studied develop Ebola.

In fact, people may not be infectious for two to three days after developing symptoms, according to a report in Monday's New England Journal of Medicine. Sensitive tests show that many people don't test positive for Ebola for two to three days after their symptoms begin because they still have very low levels of virus in their blood.

Quarantining aid workers returning from West Africa could undermine efforts to fight Ebola by deterring health care workers from volunteering to serve there, Doctors Without Borders said in a statement issued Monday.

The group said the public can be protected by carefully monitoring people when they return to this country.

"The response to Ebola must not be guided primarily by panic in countries not overly affected by the epidemic," said Sophie Delaunay, executive director of Doctors Without Borders-USA. "Any regulation not based on scientific medical grounds, which would isolate healthy aid workers, will very likely serve as a disincentive to others to combat the epidemic at its source, in West Africa."

An editorial by the editors of the New England Journalof Medicine compared quarantining doctors and nurses to "driving a carpet tack with a sledgehammer: It gets the job done but overall is more destructive than beneficial," the editors wrote in a piece published Monday. "We should be guided by the science and not the fear that this virus evokes. We should be honoring, not quarantining, health care workers who put their lives at risk."

An executive at Kaiser Permanente said he is concerned about how the company's employees will be treated when they return from West Africa. Two of the health company's 18,000 physicians are currently volunteering in West Africa with Doctors Without Borders.

The two Kaiser physicians are using vacation time. If they need to be isolated when they return, they will be put on paid leave, said Patrick Courneya, executive vice president and chief medical officer for Kaiser Foundation Hospitals and Health Plan.

"We are concerned that they will not be treated with great gratitude for the work they are doing," Courneya said.

He said volunteer doctors and nurses are essential to fighting the Ebola outbreak. He added that the threat of quarantine provides an incentive for people returning from West Africa to lie about what they were doing and whether they were exposed to Ebola.

Two medical groups -- the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America -- also issued statements Monday rejecting mandatory quarantines.

According to the World Health Organization, 10,141 people have been infected with Ebola and 4,922 have died, mostly in the hard-hit nations of Guinea, Sierra Leone and Liberia.