Viruses, viruses, everywhere

Enterovirus cladogramIt’s a scary time for those of us who fear viruses. Oh. Of course, that’s all of us, isn’t it?

Ebola outbreaks in Africa. Cases turning up in America. The potential for horrific scenes of death and destruction abound.

But don’t forget those other viruses. These days, you don’t hear so much about influenza, which remains the top killer virus in the U.S. and around the world. Nor is much said about enterovirus 68, although I personally feel it may be the most ominous of all the dangerous microbes currently making the rounds.

You see, while we are preoccupied with the horrors of Ebola in Africa, and fears of what it might do, enterovirus 68 (EV-D68 for short) has been making subtle shifts, through mutation, to become more threatening with each new, small outbreak, over a period of decades.

Look at the image above. It is called a cladogram. It’s a sort of family tree of virus mutation, drawn up for the EV-D68 viruses isolated from sick patients in the decades since the first member of the family was identified back in 1968. The scariest thing about the cladogram is the number of branches it has. Each branch represents at least one, and sometimes several, mutations in the virus. Click it for a closer view.

So, while the world has been blissfully almost unaware of EV-D68 since its first small epidemic in 1968, the virus has stubbornly refused to go away. Instead, it has moved quietly through human populations worldwide, and has slowly changed its form.

It would seem that all this change might be of little concern to humanity. After all, the influenza and common-cold viruses are known to mutate constantly, and they seem almost a part of everyday life. They crop up somewhere in the world, and then disappear again.

But there are signs in the medical literature that suggest we should not be too complacent about EV-D68. First off, it has been striking young children very hard. This implies that older people have had one or another of the previous mutants in them already and have therefor developed enough immunity to hold the virus off. But babies with naive immune systems take the full brunt of the virus’s attack. Among young kids, the disease strikes powerfully. Most alarmingly, it sometimes causes more than congestion and coughing–it can infect the nervous system and cause paralysis.

This outcome is very rare and might engender little concern for the population in general, except for one thing: EV-D68 is a member of the picornavirus family. While this is the same family as the common-cold virus, it also contains within it the deadly polio virus. And so we are now confronted with a virus that is second-cousin to polio and has been slowly mutating, almost unobserved, into a form that can cause a polio-like disease. The experts at the Centers for Disease Control and others who monitor such things are worried. So am I.

I write medical thriller novels in part to take an advance look at what might happen if one or another virus got loose in a big way. And I feel the inspiration for another book coming on right now.

If you would like an overly-detailed look into this subject, the National Library of Medicine keeps a copy of the original article on EV-D68 mutation here.

Let’s hope the mutation rate slows down a bit. Otherwise, we may be looking at big trouble.

About Tom Hopp

Thomas P Hopp is a scientist and author living in Seattle. He writes Peyton McKean mystery stories and the Dinosaur Wars science fiction series.
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