Public health officials have been nearly unanimous in rejecting the idea of a travel ban between the United States and the West African countries at the epicenter of the Ebola outbreak.

But the drumbeat from politicians demanding Ebola-related restrictions on travel intensified Friday as a number of moderate Democrats joined the chorus, including Sen. Kay Hagan of North Carolina, who is enmeshed in a tough reelection fight, Rep. Tulsi Gabbard of Hawaii and Michelle Nunn, who is running for Senate in Georgia.

“I support a temporary travel ban with the exceptions of our medical and military personnel in those affected areas in West Africa,” Nunn said Friday in an interview with The Washington Post.

Dozens of legislators have called for travel to be suspended from Liberia, Guinea and Sierra Leone, the countries most affected by Ebola.

Nunn and the others join a growing number of lawmakers from both sides of the aisle, including House Speaker John A. Boehner (R-Ohio) and Sen. Bill Nelson (D-Fla.), who have called for a ban on travel from the three West African countries.

Flights from those countries typically involve a layover in Europe before heading to the United States.

“We believe a temporary travel ban for such individuals who live in or have traveled from certain West African countries is reasonable and timely,” Rep. Bill Shuster (R-Pa.) and Sen. John Thune (R-S.D.) said in a joint statement.

The calls to ban travel and suspend the issuance of visas intensified this week after a second Dallas nurse, Amber Vinson, 29, was diagnosed Tuesday with the virus. She and another nurse diagnosed with the virus cared for a Liberian man who died of Ebola this month. Vinson flew on a commercial flight the day before she fell ill.

Lawmakers and others have said that a travel ban would help protect the United States by barring potentially infectious people from the three countries. But the calls have alarmed public health experts, who said a travel ban could result in the opposite of its intention and spread the virus throughout West Africa and beyond.

“It’s an 18th-century view that you can somehow place a cellophane wrapper around a whole region of the world and expect to keep germs out. It doesn’t work that way because it’s never worked,” said Lawrence O. Gostin, faculty director of the O’Neill Institute for National and Global Health Law at Georgetown University and director of the World Health Organization Collaborating Center on Public Health Law & Human Rights.

The United States did not put in place travel bans with the outbreak of SARS in 2003, though it did perform health checks in airports, handing out cards listing symptoms. The World Health Organization issued an emergency advisory during the outbreak, warning against travel to China, Hong Kong and Toronto.

Gostin and others said that barring travel from the three countries will spur people who want to leave to slip across porous borders into another country from which they will travel.

The Post's Abby Phillip looks past the Ebola hysteria to address three of the latest misconceptions about the deadly virus. (Davin Coburn/The Washington Post)

“Germs don’t respect borders. They will cross borders, they will go by other means, it will give them greater incentive to get out, and it will get more people infected,” he said. “It will impede medical supplies, food, humanitarian assistance.

“It would exacerbate a health and humanitarian crisis,” Gostin said. “We couldn’t do anything worse.”

In 2009, President Obama lifted a 22-year ban on travel to the United States by people who tested positive for HIV, a policy that he said was “rooted in fear rather than fact.”

Tom Frieden, director of the Centers for Disease Control and Prevention, said on Capitol Hill this week that officials just won’t know who is traveling to the United States from an affected country if flights are suspended — because they would just go somewhere else first.

“Right now we know who is coming in,” he said, and if people travel overland or from other countries, “We won’t be able to check them for fever” at designated U.S. airports.

The White House said Friday that Obama is not “philosophically opposed” to a travel ban but believes it could, in the end, do more harm than good.

“Putting in place a travel ban could have a pretty perverse effect on people who are seeking to travel to this country,” White House press secretary Josh Earnest said Friday.

Another unintended consequence of a travel ban would be its effect on the flow of thousands of medical and aid workers needed to halt the epidemic at its root, said Stephen Morrison, senior vice president and director of the Global Health Policy Center at the Center for Strategic and International Studies. Officials said this tactic is the only way to stop the virus. It is simply too expensive for the military or private organizations to fly people there, Morrison said.

According to the WHO, 4,546 people have died of Ebola in Guinea, Sierra Leone and Liberia.

A U.S. travel ban — which other countries would probably replicate — would also have a detrimental effect to the economies of the countries, effectively walling them off, Gostin said. However, he said, political pressure could dictate decisions and a compromise could be made that falls short of a ban, such as increased airport screenings.

Rep. Dennis Ross (R-Fla.) plans to introduce a bill that would restrict commercial flights and suspend the issuance of travel visas for residents of the affected countries.

“I feel that discontinuing air travel is an obvious first step solution to combating Ebola in the United States,” Ross said in a statement. “Now that two of our health-care workers have contracted the virus, I am putting my foot down.”