Moves by some U.S. states to isolate medical workers returning from fighting Ebola in West Africa could worsen the global health crisis by discouraging badly needed new volunteers, according to health experts at Harvard University.

Ebola has killed more than 5,450 people in West Africa since March in the disease's worst outbreak on record, striking hardest in Guinea, Sierra Leone and Liberia, which are among the world's least developed countries.

"By far and away what is needed most in West Africa are care providers who can help," Paul Biddinger, director of the Harvard School of Public Health Emergency Preparedness Program, said during a panel discussion about the disease on Tuesday.

But "because of a fear of stigma, of being involuntarily quarantined ... people don’t want to necessarily subject themselves to this, and that is tragic."

The United States Agency for International Development last week said that applications from medical personnel volunteering to work in West Africa had fallen by about 17 percent since the end of October, when mandatory quarantine rules were put into effect in New York and New Jersey.

In one of the highest-profile cases, a nurse from Maine who treated Ebola patients in West Africa was isolated in a plastic tent at a hospital in New Jersey for four days in October despite showing no symptoms.

Michael VanRooyen, director of the Harvard Humanitarian Initiative, said U.S. public officials needed to do better communicating clearly about the disease, and implementing precautions based on medical evidence and not fear.

"It directly impacts our ability to recruit volunteers," he said.

Ebola rates have accelerated in Sierra Leone while easing in neighboring Guinea and Liberia, prompting the head of a special U.N. mission on Ebola to admit on Monday that it would not meet targets for containing the outbreak by early December.

The United States has seen several Ebola cases and two deaths, all but two of the cases contracted in West Africa. Harvard's Biddinger said America's vast medical resources make a West Africa-style outbreak in the United States unlikely.

Despite pledges of hundreds of millions of dollars in aid and the deployment of troops by the United States and Britain, the weakness of healthcare systems and infrastructure in the worst-affected countries has hampered the fight.