Officials at five busy U.S. airports are putting in place screening measures meant to prevent the spread of the deadly Ebola virus. Screening began at JFK Airport today; it will start at other international airports next week.

The push comes as the Centers for Disease Control and Prevention announced the outbreak has killed at least 4,024 people in Liberia, Sierra Leone, and Guinea…

“But some public health officials say the procedures are unlikely to prevent anyone with Ebola from entering the country,” NPR’s Joel Rose reports. “They probably would not have stopped Thomas Eric Duncan, the first man diagnosed with Ebola in the U.S. He had no symptoms when he flew from Liberia to Dallas last month.”

As the CDC notes, airports in Liberia, Sierra Leone and Guinea have screened 36,000 potential travelers in the past two months. In that time, 77 people were kept off flights, the agency says, but none had Ebola; many of them were diagnosed with malaria.

Six U.S. military planes arrived in the Ebola hot zone Thursday with more Marines, as West Africa’s leaders pleaded for the world’s help in dealing with a crisis that one called “a tragedy unforeseen in modern times.”

“Our people are dying,” Sierra Leone President Ernest Bai Koroma lamented by videoconference at a World Bank meeting in Washington. He said other countries are not responding fast enough while children are orphaned and infected doctors and nurses are lost to the disease…

The fleet of planes that landed outside the Liberian capital of Monrovia consisted of four MV-22 Ospreys and two KC-130s. The 100 additional Marines bring to just over 300 the total number of American troops in the country, said Maj. Gen. Darryl A. Williams, the commander leading the U.S. response…

As vehicles unloaded boxes of equipment wrapped in green-and-black cloth, the Marines formed a line on the tarmac and had their temperatures checked by Liberian health workers.

Acknowledging a major “defeat” in the fight against Ebola, international health officials battling the epidemic in Sierra Leone approved plans on Friday to help families tend to patients at home, recognizing that they are overwhelmed and have little chance of getting enough treatment beds in place quickly to meet the surging need.

The decision signifies a significant shift in the struggle against the rampaging disease. Officials said they would begin distributing painkillers, rehydrating solution and gloves to hundreds of Ebola-afflicted households in Sierra Leone, contending that the aid arriving here was not fast or extensive enough to keep up with an outbreak that doubles in size every month or so.

“It’s basically admitting defeat,” said Dr. Peter H. Kilmarx, the leader of the federal Centers for Disease Control and Prevention’s team in Sierra Leone, adding that it was “now national policy that we should take care of these people at home.”…

Faced with similar circumstances in neighboring Liberia, where even more people are dying from the disease, the American government said last month that it would ship 400,000 kits with gloves and disinfectant.

The number of Ebola cases in West Africa has been doubling about every three weeks. There is little evidence so far that the epidemic is losing momentum.

“The speed at which things are moving on the ground, it’s hard for people to get their minds around. People don’t understand the concept of exponential growth,” said Tom Frieden, director of the U.S. Centers for Disease Control and Prevention. “Exponential growth in the context of three weeks means: ‘If I know that X needs to be done, and I work my butt off and get it done in three weeks, it’s now half as good as it needs to be.’”…

“The situation is worse than it was 12 days ago. It’s entrenched in the capitals. Seventy percent of the people [who become infected] are definitely dying from this disease, and it is accelerating in almost all settings,” Bruce Aylward, assistant director general of the World Health Organization, told the group…

“So we had two exports in the first 2,000 patients,” Frieden said in a recent interview. “Now we’re going to have 20,000 cases, how many exports are we going to have?”

The missteps in Dallas’s handling of the first Ebola case diagnosed in the United States have revealed an uncomfortable reality: state and city plans for handling the deadly virus are based on generic recommendations for everything from measles to floods, to hurricanes and dirty bombs.

Officials acknowledge they need to do more…

If they are not able to stay one step ahead of any cases, then lapses that characterized Ebola patient Thomas Eric Duncan’s treatment in Dallas could recur. In the Texas case that led to unnecessary exposure to the victim.

“To think the first patients would go flawlessly are an overestimation of our systems,” said Dr. Craig Smith, medical director for infectious disease at University Hospital in Augusta, Georgia. “I would expect there would be a few stumbles.”

* There is no written-in-stone understanding of Ebola transmission, because viruses mutate in the wild and the more people who are infected, the greater the opportunity for mutation. Think about that for a minute–we really don’t know the exact limits of transmission right now. And what we do know is terrifying. Have you wondered why Ebola protocols call for washing down infected areas with chlorine? Because the virus can survive for up to two weeks on a dry surface.

* We’re rapidly approaching the point where the best case scenario is a horrifying devastation that’s limited to the African continent. The worse case scenarios get nigh unthinkable awfully fast.

* Do you really want to be scared? Whether or not you realize it, Ebola is a weapon of mass destruction. What’s to stop some jihadi from going to Liberia, getting himself infected, and then flying to New York and riding the subway until he keels over? I understand that ISIS doesn’t tend to use suicide bombers as much as other jihadi groups, but this is just the biological warfare version of a suicide bomb. And can you imagine the panic if someone with Ebola vomited in a NYC subway car? Is this scenario highly unlikely? Without question. But we take drastic precautions against unlikely scenarios all the time. Just look at the massive infrastructure we’ve built for airport security based on two highly-unlikely actions.

What about “suicide sneezers,” you may ask? Someone who deliberately infects herself with Ebola and then proceeds to pass it on to others?

That’s a losing game for the terrorist. Someone with Ebola isn’t infectious until she has symptoms, and even then, there is often only a small window for action before the disease takes hold. Many people who contract Ebola do so while caring for someone who is crippled by the affliction. A terrorist who wants to infect others isn’t likely to be functional enough to run around spreading the disease for very long—and even then, will find it hard to transmit the virus…

What about now, though? Could a bioterrorist group—or, more likely, a secret national bioweapons program, like the one run by the Soviet Union during the Cold War—take Ebola and modify it to be airborne or more contagious? It isn’t likely. Why? One, because it is really difficult—we just don’t know enough about viruses to spontaneously engineer new traits. There is also a whole host of other nasty bugs that are already better designed to be weapons. Bugs like smallpox. If terrorists are going to go to all the trouble of engineering a bioweapon, they are likely to pick a much, much better starting point than Ebola.

“The ultimate the risk to America is very, very, very small,” says Ashish K. Jha, MD, MPH, K. T. Li Professor of International Health and Health Policy Harvard School of Public Health and Director of the Harvard Global Health Institute. “I understand the fear. It’s a deadly disease. That Mr. Duncan died in a Dallas hospital made it that much more dramatic. Even though it doesn’t spread easily, not remotely as easily as the flu, it’s scary. But to me the real issue is that the growth of the disease continues in West Africa—it’s worse today than it was last week. To the extent that it doesn’t get stamped out, it will continue to pose risk to rest of world. But aside from horrendous tragedy in West Africa, we’ll continue to see Ebola patients just once in a while here in the U.S.”

He adds that our energies are largely misdirected: “In [an] ideal world, you’d see—instead of fear—a resolve to stamp it out of West Africa.”…

“The problem is that every time someone has fever and has been in Africa, the media are reporting it,” says Jha. “People are getting excellent assessment care here; that’s actually good. I’d rather have a thousand false positives than to miss one real case. The problem is the media: Every fever patient becomes a message of, “Oh my God, suspected Ebola case!’ The narrative in the media then becomes, ‘This Is Everywhere!’” And that’s, unfortunately, what the majority of the headlines reflect.

Although the outbreak is a substantial threat in West Africa, a region plagued by weak government and failing public health systems, the risk to Americans is currently minimal. By contrast, the seasonal flu kills thousands of people every year but receives relatively little attention

This political attention may be contributing to the shift in public focus toward Ebola and away from more significant health threats like the flu. Where Google Trends information is available on both diseases, the data indicate that the relative frequency of searches for Ebola has increased more during the last two weeks in states where the issue has been politicized. It’s possible that politicians in those states are reflecting public opinion rather than causing the shift, but either way the trend is troubling…

A similar approach finds no equivalent increase in flu searches, which are slowly rising but, not surprisingly, are dwarfed in frequency by Ebola.

We shouldn’t be surprised that people are panicking about Ebola. It’s a fundamental part of human psychology to pay disproportionate attention to novel threats and risks. But it’s always troubling to see how often our institutions and elites encourage those tendencies rather than trying to counteract them.

Via the Corner.