Viruses can spread on non-respiratory particles like dust

Airborne viruses such as the flu and COVID-19 can spread through the air on dust, fibers, and other microscopic particles, according to a new study from UC Davis and the Icahn School of Medicine at Mt. Sinai.

The research is shedding new light on virus transmission, with major implications for the ongoing pandemic and the upcoming flu season.

“It’s really shocking to most virologists and epidemiologists that airborne dust, rather than expiratory droplets, can carry influenza virus capable of infecting animals,” said study co-author Professor William Ristenpart of the UC Davis Department of Chemical Engineering.

“The implicit assumption is always that airborne transmission occurs because of respiratory droplets emitted by coughing, sneezing, or talking.” The flu virus is believed to be transmitted in several different ways, such as through droplets released from the respiratory tract. The flu is also known to spread through contact with objects like door handles, and these secondary objects are called fomites. 

It remains a mystery which route of transmission is the strongest. The answer to this important question may be different for various strains of the flu virus or for other respiratory viruses, including coronaviruses.

Professor Ristenpart collaborated with virologists at Mt. Sinai to investigate whether tiny, non-respiratory particles called “aerosolized fomites” could pass the flu virus along among guinea pigs.

The experts used an automated particle sizer to count airborne particles. They found that uninfected guinea pigs released up to 1,000 particles per second as they moved around a cage. 

The study revealed that guinea pigs which were known to have immunity to the influenza virus were able to transmit the virus through the air to susceptible guinea pigs. This showed that the virus did not have to originate in the respiratory tract to be infectious.

In addition, a trial with microscopic fibers proved that an inanimate object such as a facial tissue could carry infectious viruses.

“Transmission via dust opens up whole new areas of investigation and has profound implications for how we interpret laboratory experiments as well as epidemiological investigations of outbreaks,” said Professor Ristenpart.

The study is published in the journal Nature Communications.

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By Chrissy Sexton, Earth.com Staff Writer