A Washington Post poll found that 43 percent of Americans are "very worried" or "somewhat worried" that they or their immediate family members will contract Ebola. In a CNN poll, 45 percent described the Islamic State as a "very serious" threat. Humorist Andy Borowitz says CNN's new slogan is "Holy Crap, We're All Gonna Die."
From the panic, you might forget that Ebola is actually hard to get because it requires physical contact with the bodily fluids of someone who is not only infected but symptomatic. It's not a new pathogen, and the methods required to contain it are well-known -- though not always easy to implement in poor countries.
The infection of two Dallas nurses who treated Thomas Eric Duncan, who died of Ebola, indicates it can spread even when serious precautions are taken. That is worrisome news if you work in a hospital. But it doesn't magnify the microscopic risk to the rest of us.
The peril posed by the Islamic State is even more remote. Despite being at war with us for two decades and despite branches in several countries, al-Qaida has not been able to carry out an attack in the United States since 9/11, more than 13 years ago. Yet somehow this newer and smaller group, which is occupied fighting a war in the Middle East, is supposed to be poised to do something that has eluded Osama bin Laden and his confederates.
The most virulent fears attach to the southern border, where terrorists allegedly are streaming in with slaughter on their minds. Republican Rep. Duncan Hunter of California said that "at least 10 ISIS fighters have been caught coming across" and dozens more have gotten away -- a claim dismissed by the Department of Homeland Security. Gary Painter, sheriff of Midland County, Texas, announced that Border Patrol agents have found "Quran books" and "Muslim clothing."
It's conceivable that the Islamic State would fly operatives to Mexico to make arduous hikes across the Chihuahuan Desert, but not particularly plausible. If that were such a swell option, al-Qaida would have made use of it long before now. Hunter and Painter have yet to produce Qurans or clothes or any other proof that violent Islamists have been lurking about.
John Wagner, an official of U.S. Customs and Border Protection, recently told Congress, "The number of known watch-listed persons we are encountering on the Southwest border is minimal compared to commercial aviation. We're talking tens versus thousands."
Deep anxieties often involve brown migrants sneaking over from Mexico. Last summer, alarmists feared that Central American kids were bringing in Ebola. But when Ebola arrived, it came via commercial airliner. If Islamic State plans to send jihadi, it probably would do likewise.
If these fears were merely irrational and misinformed, they might be reasonably harmless. But they encourage policies that are far more hazardous than the threats they are supposed to defuse.
Banning travel to and from African countries with Ebola outbreaks would impede medical professionals and supplies from getting there -- while keeping out mostly people who are perfectly healthy. It would aggravate economic disruption in countries that are already short of resources to fight disease. World Health Organization Director-General Margaret Chan says 90 percent of the costs of Ebola "come from irrational and disorganized efforts of the public to avoid infection."
Similar problems arise with efforts to counter the Islamic State. The Obama administration vowed to avoid the use of ground troops, but Joint Chiefs of Staff Chairman Martin Dempsey has said they may be necessary. House GOP leaders are demanding them.
A CBS News poll found that 44 percent of the public, including the majority of Republicans, favors ground forces. But if the most recent invasion of Iraq didn't work, it's a fantasy to think a new one would.
Americans have a way of letting their fears get the best of them. That's where things get truly scary.