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.

Contrary to administration warnings, this does not mean impeding the travel of essential medical personnel to the region to help stamp out the epidemic at its source. Trained medical and other aid experts should be supported in going to West Africa, but as the lesson of New York doctor Craig Spencer makes clear, they need to be more closely monitored in country and upon their return. In particular, they should be restricted in returning to medical or other work involving close physical contact with others in the United States until they are cleared of any risk of infection.

Equally misguided is the contention by Thomas Frieden, head of the Centers for Disease Control and Prevention, that a visa suspension would drive affected travelers underground, leading them to sneak into the United States unscreened and unmonitored. Whether a Liberian flies to Europe or drives across Africa to an airport in an unaffected country, he or she would still have to present a Liberian passport to board a plane to the United States. At that point, a visa suspension would result in a denial of boarding. Nor is it realistic to fear that our hypothetical traveler would sneak across our land borders. First, we can and should coordinate a visa suspension with Canada and Mexico. Second, smugglers are unlikely to welcome migrants who may be physically unfit to make an arduous trip while posing a threat to the safety of the smugglers themselves.

To be sure, it is possible to conjure scenarios in which foreign citizens denied visas forge passports from other nations. But in the wake of the 9/11 attacks, we and other countries substantially upgraded anti-counterfeiting protections that can be easily adapted to detect those who seek to evade travel restrictions.

Of course, the visa suspension I suggest would not guarantee that no Ebola sufferer would enter the United States. But health officials, of all people, should not argue that protective measures are unwarranted unless they are 100 percent effective. Public health professionals continually urge us to eat right, get checkups and engage in other preventive behavior to reduce illness rates, even if those rates cannot be driven to zero. Travel restrictions that reduce the number of Thomas Duncans traveling to the United States are the kind of prudent risk management that health experts applaud in other contexts.

I don’t doubt the sincerity of health officials who assure us that we will not likely see a major Ebola outbreak in the United States. But after the mishandling of the few cases we have had — including allowing an infected nurse to travel by air — we are close to a crisis of confidence. A few more bungles and we will see significant numbers of people canceling trips, closing schools and staying home from work. The essence of effective public crisis management is bold and aggressive action demonstrating that leaders are in control of events, not reacting in a halting and belated fashion. Targeted visa suspension is one of several steps urgently needed.