There is no shortage of verbiage for vomiting, but surprisingly little is known about the physics behind blowing chunks or how infections are spread as a result of regurgitation. Previous anecdotal evidence has suggested that virus particles—specifically norovirus, the leading cause of acute gastroenteritis in the United States—might go airborne in the process of puking. But according to food virologist Lee-Ann Jaykus of North Carolina State University in Raleigh, “nobody had ever proven in a lab model that the virus can be aerosolized by vomiting.” To rectify that, Jaykus and her team built a miniature “vomiting machine,” a quarter-scale model of the human digestive system complete with an artificial stomach, esophagus, and mouth. They designed it to mimic all the pressures and volumes present in hurling humans and then inoculated its “stomach” juices with a virus called MS2 (which is similar to the size, shape, and composition of norovirus but not dangerous to humans). They ran the machine in an airtight chamber connected to a sensor that could detect any floating virus particles. The team, reporting today in PLOS ONE, used a variety of different pressures, vomit viscosities, volumes, and virus concentrations and found that—in every instance—MS2 virus particles could be detected in the air. As expected, more virus particles were aerosolized when more MS2 had been added to the stomach, and both the vomit viscosity and the system pressure proved to be important variables. The most viruses—more than 13,000 particles—were observed with high initial virus concentration and high viscosity vomit. According to the team, the results confirm the plausibility of anecdotal reports of norovirus being transmitted through the air following a round of retching.
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