Why no US travel bans from Ebola hot spots? They might make things worse.

Ohio Gov. John Kasich (R) says it "makes sense." Texas Gov. Rick Perry (R) calls it the "right policy." And House Speaker John Boehner (R) of Ohio said President Obama should "absolutely consider" it.

What they want is a travel ban aimed at preventing the spread of Ebola from three West African nations. The reason they are not getting it is that the Obama administration – and many public health experts – think travel bans don't help, and instead could make things worse.

The logic behind travel bans is clear. The Ebola outbreak has become a public health crisis in Liberia, Sierra Leone, and Guinea. By banning flights to and from those countries, or by banning residents of those countries from coming the United States, politicians hope to prevent an outbreak here.

So far, three cases of Ebola have been diagnosed in the US. The first patient, Liberian Thomas Eric Duncan, died after being misdiagnosed at first by a Dallas hospital. The hospital's parent company apologized in full-page ads in the Dallas Morning News and the Fort Worth Star-Telegram Sunday.  Two nurses who treated Mr. Duncan have also been diagnosed and are being treated themselves.

The problem with resorting to a travel ban in an attempt to head off future cases, critics say, is that nations can't really cordon off health crises to a far corner of the globe. Instead, it's more helpful to be a part of the solution.

For example, a report by the Joint United Nations Program on HIV/AIDS found that a Reagan-era ban on people with AIDS coming to the US was "an ineffective and discriminatory anachronism of a by-gone era." Another study by Harvard University epidemologist John Brownstein found that airport closures in the eastern US in 2001 affected the flu season, but only by two weeks.

Perhaps of greater concern, travel bans can encourage travelers to lie about where they've been.

"If we were to put in place a travel ban or a visa ban, it would provide a direct incentive for individuals seeking to travel to the United States to go underground and to seek to evade this screening and to not be candid about their travel history in order to enter the country," said White House spokesman Josh Earnest Thursday. "And that means it would be much harder for us to keep tabs on these individuals and make sure that they get the screening that's needed to protect them and to protect, more importantly, the American public."

A travel ban might also curtail America's ability to help address the outbreak at its source.

"When some commercial flights stop going into those countries, our people are delayed going in, our people are delayed going out," said Tom Skinner, a spokesman for the US Centers for Disease Control and Prevention. "When we stop commercial flights in and out of the country, it does not enhance our ability to stop the epidemic."

In the past, the US has not imposed travel bans – and the World Health Organization has not recommended them – for the swine flu (H1N1) in 2009 and 2010 or for the SARS outbreak in 2003. Public health officials say both those diseases are more contagious than Ebola, which can be contained with careful treatment protocols.

Some 94 percent of travelers to the United States from Liberia, Sierra Leone, and Guinea come through one of five airports: New York's John F. Kennedy, Newark, Chicago O'Hare, Washington-Dulles, or Atlanta Hartsfield-Jackson. Screening procedures are under way there.

There are no direct flights from any of those countries to the US.