Norovirus sickens 20 million people in the U.S. every year, despite attempts to wash hands and avoid contaminated surfaces.
A group of researchers wondered if its prevalence might in part be the virus taking to the air during the act of vomiting. The catch was: there was no easy way to test that theory.
So, they built a vomit machine. And, they found the germ could indeed take to the air, as they wrote in a study published today in the journal PLoS One.
“Epidemiological evidence has pointed to virus aerosolization during vomiting as a likely route for spreading norovirus, and our work here confirms that it’s not only possible by probable,” said Lee-Ann Jaykus, professor at North Carolina State, and a co-author of the paper. “When one person vomits, the aerosolized virus particles can get into another person’s mouth and, if swallowed, can lead to infection.”
The scientists first debuted their vomit machine on Youtube last November. It was built to simulate the physiologically relevant pressures of the stomach and esophagus – as well as the viscosity of the average spew of stomach contents.
When the machine projected the simulated vomit, it was into a clear box with a sampler at the other end.
The team, from both North Carolina State and Wake Forest University, found that not much of the virus was made airborne – but enough of it was to explain easy transmission.
“In terms of overall percentage, not a lot of the virus is aerosolized,” says Francis de los Reyes III, a professor at NC State and corresponding author of the paper. “But in absolute terms, it is a lot compared to the amount of virus needed to cause infection.”
“That can still amount to thousands of virus particles – more than enough to infect other people,” Jaykus added.
The findings may help cleaning up after a bout of illness – and keeping that illness from spreading, the scientists said.
“These experiments have implications for better understanding the transmission dynamics of human norovirus and for risk modeling purposes, both of which can help in designing effective infection-control measures,” said Grance Tung-Thompson, a doctoral student and one of the authors.