October 26 at 7:43 PM

Michael Chertoff was secretary of homeland security from 2005 to 2009 and is co-founder and executive chairman of the Chertoff Group, a security and risk-management firm. 

As alarm mounts over the spread of Ebola, many are concerned that screening travelers who arrive in the United States from West Africa is not sufficiently protective because it will not identify those who carry the virus but are not yet symptomatic. Yet over the past two weeks, the Obama administration and supportive experts saturated the media with the argument that any comprehensive travel restrictions aimed at Ebola-infested regions would be pointless and even counterproductive.

No doubt the experts who reject travel bans understand disease and epidemiology. But their arguments demonstrate less understanding of how we manage risk in the context of border and travel security. In fact, restriction of U.S. travel visas for residents of Liberia, Guinea and Sierra Leone — the three countries in which Ebola is out of control — could reduce the risk of significant disease import into the United States without hampering efforts to assist those nations in combating the illness.

During my time as U.S. homeland security secretary, we planned extensively for the possibility of a global pandemic — specifically, mutated avian influenza. If that virus had achieved efficient human-to-human transmission, it would have rapidly globalized, and closing borders would have had little lasting impact. Simply put, it is difficult to shut out the entire world.

But Ebola is not a highly efficient contagion. For months, the vast majority of cases have been concentrated in Liberia, Guinea and Sierra Leone. There, the disease is still uncontrolled due to inadequate medical infrastructure and family-oriented medical and burial customs. As demonstrated by the tragic case of Thomas Eric Duncan, the Liberian man who died of Ebola in Dallas, there is a real risk that people who come into contact with a contagious individual in these countries could bring the disease to the United States.

Unlike in a global pandemic, it is possible to reduce the risk of Ebola importation by suspending all but essential travel to the United States from just those three nations. The government simply has to suspend travel visas for citizens and residents of those nations.