Today, The Guardian relayed one of those stunning medical stories that causes me to clean off my glasses and take another look to make sure I’m reading it clearly. They report that an outbreak of norovirus in Britain this winter has struck more than 1.1 million people with vomiting and diarrhea.

That’s right: 1.1 million. In Britain alone.

What is this fearsome bug, you may be asking, and why isn’t it the subject of a Hollywood horror movie?

Noroviruses are one of virology’s great open secrets. In a recent issue of The Journal of Infectious Diseases, Aron Hall of the Centers for Disease Control declared, “Noroviruses are perhaps the perfect human pathogen.”

Here’s what inspires awe in scientists like Hall.

Each norovirus