Norovirus is a nasty bug that brings about inflammation in the stomach and intestines leading to pain, nausea, diarrhea and sometimes even death. It affects around 20 million people per year in the US, but despite its rampant nature, questions remain over how exactly it is transmitted. To shed further light on how one of the world's most common pathogens spreads between humans, scientists have built a vomiting machine to study its behaviour when projected into the air.

Earlier studies have indicated that norovirus can become aerosolized when a person vomits. This means that particles containing the virus can become airborne post-puke, lingering threateningly in the air or on surfaces ready to infect innocent bystanders. But these have only really been suspicions rather than proven scientific fact, so a team from North Carolina (NC) State University went searching for more concrete answers.

The researchers set out to build a system that replicated the body parts integral to the process of vomiting: the mouth, esophagus and stomach. Their efforts culminated in a system that uses tubes, a pressure chamber and a sickly clay face (which weighs down the tubing to help direct the spray) sealed inside a plexiglass box. Though the device was secure, the researchers were still unable to use norovirus in the experiments, so they put a bacteriophage called MS2 in its place. MS2 is harmless to people and is regularly used as a replacement in norovirus research.

With the machine built in such a way that the researchers could dictate the pressure, volume and angle of the vomit, it spewed forth artificial chunder in a series of formal experiments. They found that of the total virus particles, only a tiny portion of less than 0.3 percent became aerosolized. This figure may seem small amount, but could equate to thousands of virus particles for a single vomit event.

"And that is enough to be problematic because it only takes a few, perhaps less than 20, to make a susceptible person ill," says Lee-Ann Jaykus, professor of food science at NC State. "This machine may seem odd, but it’s helping us understand a disease that affects millions of people. This is work that can help us prevent or contain the spread of norovirus – and there’s nothing odd about that."

The team's research was published this week in the journal PLOS One.

The short video below shows the vomiting machine do its thing.

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