For the past A few years, until the pandemic hit, Bill Ristenpart, a chemical engineer at UC Davis (and coffee-geek at the next level) had brought a team of researchers and boxes of expensive instruments across the country to New York City each summer and into the lab of Nicole Bouvier. A physician and researcher of infectious disease at Mount Sinai Hospital, Bouvier studies respiratory viruses, particularly affected. The specialty of Ristenpart is fluid dynamics. In the case of influenza, this means measuring how physical properties such as temperature, humidity, and wind speed alter the flight of the respiratory bloblets that fly from human and rodent nostrils and mouths. Together, with dozens of guinea pigs and nearly $ 2 million from the National Institutes of Health, they hope to solve a century-old mystery: Why is there a flu season?
That, they do not know yet. Instead, her work has compelled evidence that some respiratory viruses, at least in lab animals, do not always travel through liquid droplets, as scientists have long assumed. Infected guinea pigs do not breathe or sneeze bites of impact. They can actually launch infected particles into the air from their fur, legs, and cage.
Do you think ‘fomites’, those germ deposits on surfaces that lead to so much hand washing and hand wringing over face-touching in the early days of the pandemic? Now, sometimes, instead of putting on large objects such as tables and cell phones, germs cling to the surfaces of solids that are so small that you can not even see them, such as microscopic fibers, dead skin cells, and dust. Those minuscule solids can later be kicked into the air. In doing so, Bouvier and Ristenpart call them “aerosolized fomites.” And according to their research, these germic particles can make other animals sick. In fact, aerosolized fomites in their latest study appeared to be the primary way their marchers ran the flu.
“Our experiments clearly show that when guinea pigs are steaming around them. And if that substance is infected with a virus, it can pass that virus through the air to another animal in a separate cage, ”says Ristenpart. Their work also addresses the possibility that this fourth route of transmission – aerosolized fomites – could also potentially affect human health, he says. Especially during a worldwide outbreak of a new respiratory virus. “When you rub your face or brush your shirt or curl a piece of tissue paper, you aerosolize your particles on a micro scale,” says Ristenpart. “And if that surface was previously in contact with virus-containing sludge, then you are also aerosolizing virus that other people can inhale.”
The UC Davis / Mount Sinai team published these shocking findings Tuesday in the journal Nature communication. Although the experiments were carried out pre-pandemic, and with a flu virus, their results now land in the middle of a hot dispute over how the new coronavirus SARS-CoV-2 is transmitted. At the heart of the controversy is disagreement over the size, behavior, and relative importance of the droplets that infected people emit from their respirators – specifically whether these expiratory particles can travel long distances and remain in the air for long periods of time. Now, this study adds a new wrinkle. What about viral particles released into the air via other routes – stepped up from the ground, shaken out of a bed spread, shrunk from a dirty tissue? How much should people care dat?
The answer – at least for now – is probably more than a little, says Richard Corsi, dean of engineering and computer science at Portland State University, who was not involved in the study. Now an administrator, Corsi has studied the quality of indoor air for decades. He noted that humans are constantly adapting their surroundings to their movements, both by removing skin and glass fibers from clothing and disturbing clouds of particles from the floor. Some scientists have even been able to measure the unique microbes that live in these personal aerosol clouds. That he is not surprised that viruses can ride a ride in the same way as other microbes do. “I think this paper strongly suggests that we should not adopt the path of resuspension of surface fomites,” says Corsi. “It does not mean that it is the most important transmission path. But it’s a path. ”
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