Meet Larry. He’s a clay-faced machine with an important job to do. He’s puked hundreds of times in the name of science.
When North Carolina State professor Lee-Ann Jaykus wanted to study the spread of norovirus–the stomach churning virus that kills as many as 800 people in the U.S. a year, and hospitalizes another 70,000–she and her peers wondered if it was possible that infection could be spread via the airborne virus floating around in bathrooms after someone vomited.
To test the theory, her team would build a vomitbot, funded by the U.S. Department of Food and Agriculture.
“The first thing we did was go into the scientific literature, to look for what was known about human vomiting,” says Jaykus. “There was surprisingly little that was published, and most of what was published as back in the ’40s and ’50s.”
Coughing? We understand it. Sneezing? That’s pretty well understood, too. But the mechanisms behind vomiting have been a blind spot in scientific literature. So Jaykus enlisted a doctor who had studied the topic extensively. “We said, we need some information, when people vomit, what is the volume? What is the structure of the subject that might have an impact on vomiting? What’s the pressure at which it comes out?”
Then this data was turned over to an engineering team who pieced together Larry at a one quarter human scale. He’s basically a pressurized system of tubes, meant to mimic the upper end of the GI tract, but he’s built from only about $200 in materials that you could buy at Lowe’s or Home Depot. His stomach is a PVC pipe with a piston. A ball valve serves as the lower esophageal sphincter–the mechanism that normally keeps food inside your stomach. And a simpler collection of tubes represent the esophagus and mouth.
A crude clay face completes the machine.
“We put the face on to keep the [tube] angle steady while vomiting,” Jaykus says. “But I’d be remiss to say we did it to make it look more friendly.”
Researchers loaded Larry with virus-infected solution similar to norovirus, but completely harmless, and then dyed the liquid with green food coloring for ease of clean up. Inside a plexiglass box, which itself was wrapped in a biosafety hood, Larry vomited hundreds of times in a controlled environment, while an aerosol measuring device eventually proved the harrowing theory: Norovirus does transfer as an aerosol, and at dangerous numbers. Even in less extreme pressures of vomiting, up to 13,000 viruses can make their way into the air. As few as 20 can get you sick.
The question remains, though, if we don’t understand that much about the physics of vomiting, can we actually be sure that Larry got things right?
“The best way to do this [study] would be to infect someone with norovirus, go into their GI tract before they vomit, and measure all these parameters. You can’t do that,” Jaykus laughs. “So when that situation happens, and it happens a lot in science, you have to resort to some sort of a model. Are we 100% sure [our simulator is perfect]? I guess what you could say is, this is as accurate as we could make it given the current state of knowledge.”
But Jaykus has a lot of confidence in her results. She points to another recent study of norovirus–one that actually measured for air norovirus particles in the air of actual bathrooms–as having very close results to Larry’s. “I think you have to look at those two papers together,” she says. “Together, I think this really provides compelling evidence.”
[via Discovery News]