Dear Science,

Herpes. It's annoying. It's ubiquitous. I've heard that 80 percent of people have been exposed to HSV-1 (the usually oral kind) and 25 percent have HSV-2 (the usually sexual kind). Is this comparing apples to oranges? What percentage of people have what?

What is asymptomatic shedding? How does that work? Are virus particles somehow coming out of the nerves? I've heard that it can spread from the whole "boxer-short area," so how effective are condoms in stopping the spread?

Why is there no vaccine? Is it that it's super hard to make one, or that herpes isn't deadly enough that there's a giant perceived need? I think you mentioned one being worked on in Seattle—how is that going? Thanks!

Distressed By The Herp

Science finds the entire family of herpesvirus to be charming. These guys are huge, the viral equivalent of a big-rig RV—basically the biggest virus your body is ever likely to meet. When they park themselves inside one of your cells—generally an ultra-long-lived nerve cell—it's akin to a Wal-Mart parking lot just before the start of a nearby NASCAR race. The awnings roll out, a huge pile of kids sprawl all over, and the virus fires up its own barbecue and starts cooking.

You, dear reader, have pleasantly introduced us to herpes simplex virus types 1 and 2. HSV-1 loves the mouth, HSV-2 loves the genitals—but they can be convinced to swap places. Did you know there are eight types of herpesvirus? Number three is chickenpox, four and five cause mono. Six and seven cause a childhood illness with the creative name "sixth disease" (as in this is the sixth damn thing your kids got—after measles, mumps, chickenpox, and the like—before they were old enough to do something about it on their own). Herpesvirus 8 causes Kaposi's sarcoma—the spots that appear in someone with advanced AIDS.

Here's the rub. Almost everyone on the planet has at least a few herpesviruses lurking within them. While we tend to get sick initially, eventually the virus settles into our cells and our immune systems make peace with the situation. We don't feel sick. The virus slowly churns out copies of itself—to infect the next generation of people. That's your asymptomatic shedding. Condoms help, but beware of the boxer-short area. Somewhere around 20 percent of New Yorkers have HSV-2, 60 percent have HSV-1. The overwhelming majority has no symptoms.

A vaccine was developed for the chickenpox-causing member of the family, and a huge trial for a vaccine against HSV-1 and HSV-2—organized right here in Seattle—just ended, with the data undergoing analysis as you read this column.

And, while most of us barely notice our lifelong infections with herpesvirus, some new data found a connection between Alzheimer's disease and HSV-1. Pucker up! recommended

Droolingly Yours,

Science

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