It had to happen.

A few schools in Ohio and Texas have closed in the wake of the news that (a) a second nurse who had cared for the late Mr. Duncan, the first victim of Ebola to die in the United States, has contracted the disease, (b) this nurse had traveled (apparently to enlist her mother in wedding planning) by plane between Ohio and Texas, and (c) there were school-age children on one or both flights.

These kids may, or may not, have had any direct contact with the nurse. She may, or may not, have been sufficiently symptomatic when on the flight to have been contagious. And, because news of the “exposure” came only after these kids had been able to attend school, to ride school buses and to eat in the cafeteria, the schools were closed.

Meanwhile, the incubation period, 21 days, will pass slowly. If the schools can be “decontaminated” quickly enough, most kids will lose only a few days of school. The teachers in the Ohio schools, at least, will just need to hope for fewer snow days this winter to keep up with their preparations for the students’ all-important assessments.

Of course, the threat of death is a far more serious concern than academic progress. The former, if realized, eliminates any concern about the latter.

But the threat of death is real, every day, in a variety of ways we simply ignore. As horrific as the deaths in West Africa from Ebola have been, the numbers still are small compared to much more familiar diseases. Out of fear of the possible, generally rare, and often hyped, adverse effects of vaccinations, hundreds, perhaps thousands of parents have refused to have their children immunized against measles and a number of other diseases. Measles kills an estimated 164,000 individuals every year world-wide, more than half of them in India. According to the Centers for Disease Control, “Measles spreads through the air by breathing, coughing or sneezing. It is so contagious that any child who is exposed to it and is not immune will probably get the disease.”

So . . . shall we ban travel from India, since there are thousands of children in the U.S. today who have not been immunized against measles, and there are tens of thousands of people in India, in any given year, who are contagious with the disease for a period of time?

Just for comparison’s sake, the World Health Organization indicated this week that there had been 9,000 confirmed or suspected cases of Ebola in West Africa this year to date. I’ll add that travel volumes between the U.S. and West Africa are much lower than those between the U.S. and India as well.

Is Ebola scary? You bet. The disease is remarkably lethal; while nearly everyone who has been in the United States for treatment for Ebola so far has survived (Mr. Duncan being the tragic exception to date), fatality rates in West Africa may be over 50 percent. And there’s no cure, no vaccine, no anti-viral known at this point to knock Ebola out. Compared to measles today, the danger, once a victim has contracted the disease, is much, much greater with Ebola than with measles.

But the best available evidence is that it actually isn’t that easy to contract Ebola. So far, it does not appear that an Ebola victim is contagious until they have symptoms. Once they have symptoms, transmission of the disease requires exposure to body fluids and the transfer of those fluids to some mucus membrane in the new victim’s body.  Not the sort of thing that happens just because one happens to be on the same airplane, while it certainly is the kind of thing that can happen to a nurse who must clean up after an Ebola sufferer’s symptoms.

That’s the problem in West Africa. People become ill, and others, untrained or poorly trained and, at least as important, very poorly equipped and supported, care for them. That’s what human beings do.

When they hold their sweaty hand or clean up after them, these caregivers . . . mostly family members, friends and volunteers, as well as professional health care workers . . . come in contact with the fluids that put them at risk. Without proper equipment, without proper decontamination, the likelihood that they will contract Ebola themselves is pretty high.

But that’s about overt symptoms and direct exposure. It’s not about being on the same plane, the same bus, or in the same cafeteria.

Let’s not let fear run away with us. Let’s be serious, and realistic, about the risks, to be sure. But realism means dealing with facts, not hysteria or political talking points.

The stakes really are much too high for that.