One of your humble Newton correspondents (okay, it was me) was recently diagnosed with shingles -- that nasty, itchy, burning rash that only old people are supposed to get. Sure, your correspondent doesn't exercise as often as he should, and he doesn't eat exactly the way the Obama Administration wants him to, but overall, he's a relatively healthy 30-year-old. How could he come down with shingles? And what exactly causes shingles?
If you have ever had chickenpox, you are at risk of developing shingles. Chickenpox, a.k.a. varicella zoster virus, is a type of herpesvirus, specifically human herpesvirus-3 (HHV-3). Herpesviruses are famous for causing, you guessed it, herpes. And thanks to this television commercial, we know that moderately attractive people can take the anti-viral medication Valtrex to treat genital herpes... but there is no cure. (Or, as a microbiology professor I know once said, "Love is temporary, but herpes is forever.")
Why? Because herpesviruses set up shop in your nerve cells and never leave. Even after you clear the active infection, they hide in what is known as a latent infection. Every so often, the virus reactivates and reestablishes an active infection, often referred to as an "outbreak." People who have genital herpes regularly go through these active-latent cycles. (It should be pointed out that this active-latent infection model has come under serious attack recently.)
Being a herpesvirus, chickenpox behaves very similarly. After you clear the initial chickenpox infection, some viruses survive, forever, inside your nerve cells, and occasionally, they can reactivate. However, instead of causing chickenpox, they cause shingles. People in their 60s and older are most susceptible to shingles, and the average person (who had a prior chickenpox infection) has about a 30% lifetime risk of developing shingles.
But recently, scientists have noted that younger and younger people are suffering from shingles, and ironically, the chickenpox vaccine might be to blame.
It's hypothesized that people who have been previously infected with chickenpox benefit from being exposed to the chickenpox virus throughout their lives. For some reason, constant exposure to chickenpox might suppress shingles. But since children these days are being vaccinated against chickenpox, there is less chickenpox virus circulating in our communities. With less chickenpox around, those of us who were previously infected are no longer being exposed to the virus. And, for unknown reasons, this might trigger the latent virus inside our nerve cells to reactivate, causing shingles.
Is the hypothesis correct? Nobody knows. But if it is, then we can expect that more and more people in their 30s and 40s will succumb to shingles. So it might not be a bad idea to stock up on some calamine lotion, just in case.