WASHINGTON (AP) — Mandatory 21-day quarantines on health care workers returning from Ebola-ravaged West Africa, like those put in place by three states, can have the unintended consequence of discouraging them from volunteering, a top federal health official said Sunday.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said that as a physician and scientist, he would have recommended against a quarantine.

"The best way to protect us is to stop the epidemic in Africa, and we need those health care workers so we do not want to put them in a position where it makes it very, very uncomfortable for them to even volunteer to go." he said.

He said active and direct monitoring can accomplish the same thing as a quarantine because people infected with Ebola do not become contagious until they start showing symptoms. Ebola is transmitted through direct contact with the bodily fluids of an infected person.

New York, New Jersey and Illinois imposed mandatory quarantines after Dr. Craig Spencer, a Doctors Without Borders physician who treated patients in Guinea, was diagnosed with Ebola last Thursday. The doctor, who is now in isolation at New York's Bellevue Hospital, had been on the subway, went bowling and to a park and restaurant before showing symptoms

Gov. Chris Christie, R-N.J., said he concluded the quarantine was necessary to protect public health in his state and that he thinks the Centers for Disease Control and Prevention "eventually will come around to our point of view on this."

Christie said Fauci was counting on "a voluntary system with folks who may or may not comply."

The governor pointed to an NBC News crew that had returned from West Africa was supposed to self-quarantine because its cameraman was hospitalized with Ebola. "Two days later they were out picking up takeout food in Princeton and walking around the streets of Princeton," he said. The cameraman has recovered and has been released from the hospital.

Fauci said Spencer did exactly what he should have done by putting himself in isolation as soon as he developed a fever. "No one came into contact with his body fluids," Fauci said. "The risk is essentially zero, vanishingly small."

Fauci said the health care workers returning from treating Ebola patients are responsible and know that if they have symptoms there's the possibility of transmitting the disease. "They don't want to get anyone else infected," he said.

As for the unintended consequences, he said, "If we don't have our people volunteering to go over there, then you're going to have other countries that are not going to do it and then the epidemic will continue to roar," he said.

Samantha Power, the U.S. ambassador to the United Nations who is on a trip to West Africa to highlight the need for increased international support to combat Ebola, spoke of a need to ensure that returning U.S. health care workers "are treated like conquering heroes and not stigmatized for the tremendous work that they have done."

Fauci appeared on "Fox News Sunday," ABC's "This Week" and NBC's "Meet the Press." Christie was interviewed on Fox and Power spoke to NBC.