On May 9, the World Health Organization stopped short of calling Middle East respiratory syndrome, or MERS, a global health emergency. That's a good thing.
In the 2 1/2 years since it was first identified, MERS has had a case fatality rate of about 30%, which sounds alarming. But during that period, there have been only 594 confirmed cases. Moreover, extensive surveillance in Saudi Arabia has shown that many people infected with the virus never showed symptoms, which means the fatality rate is actually far lower.
Still, case numbers have shot up in recent weeks. And the first two infections in the United States were recently reported, both of them in healthcare workers who flew in from Saudi Arabia. (A third man reportedly contracted MERS from one of these patients but did not become sick.)
This has brought on the usual spate of pandemic alarm on the part of the news media, along with the repeated insistence that all viruses, everywhere, are only a plane ride away.
That is true, of course. Infected people can always get on a plane and end up in your neighborhood hospital: people with Ebola, SARS or now MERS. But that doesn't mean you're in danger or that pandemics of these or other diseases are likely.
One frequent assertion of the alarmists is that dangerous viruses will "mutate to transmissibility," meaning that organisms will acquire the ability to be transmitted easily from human to human. That actually happens very rarely.
As virologist Vincent Racaniello of Columbia University notes: "MERS has been in the Middle East for some time, at least since the '90s, and hasn't spread significantly. In my view, once you find a new virus and determine that it hasn't spread for a few years, that's the end; it's not going anywhere…. I don't think this virus has even the potential that SARS did."
And the 2003 outbreak of SARS, he points out, infected only about 8,000 people worldwide, killing 800. That's a long way short of a true pandemic. As for MERS, "Efficient human transmission isn't in the cards," says Racaniello.
In other words, MERS isn't, and likely never will be, a human-adapted disease. The virus probably began in bats and is now well established in camels. Some cases of human infection have been traced to contact with the ill-tempered, frequently spitting beasts. But camels all over the Middle East are infected; camel meat tested in Egyptian slaughterhouses shows a nearly 100% rate of infection. Yet there are no reports of human MERS cases in Egypt.
Racaniello says there is a great deal about the epidemiology of this virus — how it's actually getting into people — we still don't understand. Like SARS, though, most cases of human-to-human transmission have been in hospitals, where putting patients on respirators sprays invisible droplets in the air. That kind of artificially aided transmission doesn't make MERS a human-adapted disease.
But while we're worrying about MERS, a much older, more insidious virus continues its spread. Poliovirus evolved, long ago, into a purely human-adapted disease, and it's much better at spreading among us than MERS ever will be. Once pent-up, more or less, in its last redoubts in Nigeria, Pakistan and Afghanistan (though now eradicated — after a long struggle — in India), poliovirus has been moving silently in recent years into much of Africa as well as parts of Asia and the Middle East. A recent acceleration of cases has prompted the WHO to rightly label polio's spread a global emergency.
Olen Kew, a senior virologist specializing in polio at the Centers for Disease Control and Prevention, says that the WHO warning, while alarming, shows how far the campaign has come. Years ago, he notes, health professionals simply accepted that polio was part of life. Now, Kew says, any uptick is viewed as unacceptable as the world moves toward eradication. The work has been impeded by civil unrest in Pakistan, Syria and Central Africa, along with murderous attacks on vaccinators in some areas. But Kew insists that the battle against polio is being slowly won.
Still, if Americans who oppose vaccination — believing, apparently, that the risk of a crippling disease is preferable to exposing their children to a dead virus and a needle prick — gain strength, this specialist in human misery could come creeping back into the United States. And that is a risk far worse than a few cases of MERS.
We need to get our priorities straight, as the WHO apparently has done. The threat isn't MERS, a camel or bat disease that sometimes infects humans. It is instead the real possibility that a truly deadly human disease could regain a strong foothold in the world.
Wendy Orent is the author of "Plague: The Mysterious Past and Terrifying Future of the World's Most Dangerous Disease" and "Ticked: The Battle Over Lyme Disease in the South."