The Stomach-Flu Mystery

Why is norovirus, which causes most cases of gastroenteritis, so easily spread? Scientists built a vomiting machine to find out.

Lisi Niesner / Reuters

On the first day of my vacation last week, I had just finished covering myself in sunscreen when I felt my knees go weak. I ran for the bathroom, where my body cleared itself of its contents with the fury of a surface-to-air missile. Almost as suddenly, my back and legs started feeling like they had been pounded with meat mallets. I crawled into bed, and there I stayed for the next 24 hours.

If I had, at that point, possessed enough strength to shake my fist at the heavens, I would have done so and said, “Damn you, norovirus!”

Norovirus is a highly contagious bug that’s the most common cause of what we call “stomach flu,” or gastroenteritis. Most people get norovirus from restaurants, usually from a sick employee or from contaminated raw food, according to the Centers for Disease Control and Prevention. It’s no wonder it has ripped its way through cruise ships in a matter of days: It can take as few as 18 particles of norovirus to make you sick, and the stuff can live on silverware and countertops for weeks.

A team of scientists in North Carolina had been wondering whether there’s yet another, more covert, way for norovirus to spread: Through the air. When someone retches—as they so often do with norovirus—does the virus hang in the air and infect others?

The answer is, grossly, yes. To test their theory, the researchers built a machine that simulates vomiting, complete with a creepy humanoid head. They poured a “simulated vomitus” (vanilla Jell-O instant pudding) that had been infected with a norovirus-like pathogen called MS2 into a pressurized stomach chamber.

When the vomiting machine spewed, small amounts of MS2 wafted in the vomit’s wake. Translating their findings to a real person’s vomit, this means at least 36 norovirus particles would be airborne after someone pukes—twice the amount that’s needed to infect a person with norovirus.

This study suggests it’s even more difficult than previously thought—and it was already considered pretty arduous—to prevent norovirus infections.

“Those airborne particles could … land on nearby surfaces like tables and door handles, causing environmental contamination,” Lee-Ann Jaykus, a North Carolina State food-science professor who oversaw the study, told NBC News. “And norovirus can hang around for weeks, so anyone that touches that table and then puts their hand to their mouth could be at risk for infection."

Short of equipping all citizens with personal bubbles to roll around in, one way some states and municipalities are trying to reduce this threat is by mandating sick leave for hourly workers. Infected food-service workers cause 70 percent of all norovirus outbreaks, and one in five of these workers reports working while sick because they fear losing their jobs or can’t afford to go without the day’s pay.

If they were able to stay home, they could keep their clouds of norovirus air to themselves—and spare their customers a day of pain and Clorox.