The health care worker who had been under quarantine earlier today has developed a fever and is being evaluated at University Hospital in Newark for the possibility of Ebola, according to the N.J. Department of Health.

The unnamed health worker had appeared healthy when she landed at Newark Liberty International Airport Friday, officials said, but she was was quarantined anyway because of her proximity to Ebola victims.

Officials said the woman was a U.S. citizen who began her trip back to the United States in Sierra Leone, one of the three West African countries struggling to contain the outbreak of the deadly virus.

She was the first airline traveler to be quarantined under the policy announced earlier in the day by the governors of New Jersey and New York.

She is not a New Jersey resident. She spent her initial hours of quarantine in the small Quarantine Station operated by the U.S. Centers for Disease Control and Prevention at the airport, according to Donna Leusner, spokeswoman for the Department of Health.

As of Friday evening, she had been transferred to University Hospital in Newark - one of the three designated hospitals for treating any Ebola case in New Jersey - and was undergoing a medical evaluation.

While federal policy subjects anyone who has traveled to West Africa report their temperature daily for 21 days after arrival in the United States, New Jersey Gov. Chris Christie and New York Gov. Andrew Cuomo jointly announced that any passenger who had contact with Ebola victims in West Africa would be placed under a 21-day quarantine, no matter how healthy they appeared.

The move by the two governors came the day after a Doctors Without Borders physician was hospitalized with Ebola. He had flown in through JFK International Airport, and was healthy upon his arrival. His subsequent contacts and movements through the city became the subject of public health concern, triggering concerns about everything from the subways to a Brooklyn bowling alley.

Newark-Liberty and JFK are among the five nationally-designated airports permitted to receive travelers from Ebola-affected West African nations.

Christie said New York and New Jersey are going above and beyond the CDC guidelines.

"Our states have to be the most vigilant and we’re going to be the most vigilant," the governor said.

Those ordered to undergo quarantine will be required to stay in their homes for 21 days, Christie said. He said a "more rigorous and appropriate" screening process is needed at the airports, since people can't be counted on to voluntarily quarantine themselves. He cited the case of NBC Chief Medical correspondent Nancy Snyderman, who broke the Centers of Disease Control's recommendation of voluntary quarantine and was seen shopping and eating in her hometown of Princeton.

"You don’t have to hit us across the head more than once," he said.

Cuomo called it an evolving situation that requires as much caution as possible.

Govs. Cuomo and Christie announced yesterday that they were ordering all people entering the country through two area airports who had direct contact with Ebola patients in Sierra Leone, Liberia and Guinea to be quarantined. (AP photo)

"It's a situation that truly tests the capacity and the ability of the government to perform,” he said. "Ebola is a frightening disease, no doubt. There’s also no doubt that we’ve gone through several frightening situations, many difficult days. We've had many diseases that we've dealt with."

Just as with other serious outbreaks, such as SARS and the bird flu, officials are gradually learning more about Ebola and how best to respond to potential cases, Cuomo said. Both governors said the mandatory quarantines are an acknowledgement of fallible human nature — which could include the decision to break a voluntary quarantine for, say, a slice of pizza — and the realities of the fluidity between the two states.

“Voluntary quarantine? No. It’s almost an oxymoron to me,” Cuomo told reporters. “You know, in a region like this, you go out one two or three times, you ride the subway, you ride the bus, you could infect hundreds and hundreds of people.”

Under the new screening process announced today:

• There will be real-time access to on-the-ground screening at JFK and Newark Liberty International Airports by New York and New Jersey Departments of Health.

• Each Department of Health representative at JFK and Newark Liberty will make their own determination as to hospitalization, quarantine, and other public health interventions for up to 21 days.

• There will also be a mandatory quarantine for any individual who had direct contact with an individual infected with the Ebola virus while in one of the three West African nations (Liberia, Sierra Leone, or Guinea), including any medical personnel having performed medical services to individuals infected with the Ebola virus.

Additionally, officials said all individuals with travel history to the affected regions of West Africa, with no direct contact with an infected person, will be actively monitored by public health officials and, if necessary, quarantined, depending on the facts and circumstances of their particular situation.

The governors said both states were establishing "enhanced communication protocols" between their respective state health departments to coordinate on matters pertaining to New York and New Jersey resident travelers who fly into Newark and JFK.

The CDC and Customs and Border Protection will provide information to New York and New Jersey on all screening on a real-time basis and provide a daily recap as to the status of that day’s screening and determinations.

Kathleen O'Brien may be reached at kobrien@njadvancemedia.com, or at (732) 902-4557. Follow her on Twitter @OBrienLedger. Find NJ.com on Facebook.