Shocking new research shows viruses can spread through the air on dust particles

Influenza viruses can spread through the air on dust, fibers and other microscopic particles, according to new research from the University of California, Davis and the Icahn School of Medicine at Mt. Sinai. The findings, with obvious implications for coronavirus transmission as well as influenza, are published today (August 18, 2020) in the journal Nature’s communications.

“It’s really shocking to most virologists and epidemiologists that airborne dust, rather than expiratory droplets, can carry the influenza virus capable of infecting animals,” said Professor William Ristenpart from UC Davis’ Department of Chemical Engineering, which helped lead the research. “The implicit assumption is always that airborne transmission occurs through respiratory droplets emitted by coughing, sneezing or speaking. Dust transmission opens up new areas of investigation and has profound implications for how we interpret laboratory experiments as well as epidemiological investigations into epidemics.

Fomites and influenza viruses

The influenza virus is thought to spread by several different routes, including in expired droplets from the airways or on secondary objects such as doorknobs or worn tissue. These secondary objects are called fomites. However, the most important routes are not well known. The response may be different for different strains of influenza viruses or for other respiratory viruses, including coronaviruses such as SARS-CoV2.

In the new study, Sima Asadi and Ristenpart, an engineering graduate student at UC Davis, teamed up with virologists led by Dr Nicole Bouvier at Mt. Sinai to see if tiny, non-respiratory particles they call “aerosol fomites” could carry the flu virus between guinea pigs.

Using an automated particle size analyzer to count airborne particles, they found that uninfected guinea pigs emitted peaks of up to 1,000 particles per second as they moved around the cage. The particles emitted by the respiration of the animals were at a constant, much lower rate.

Guinea pigs immune with the influenza virus painted on their fur could transmit the virus by air to other susceptible guinea pigs, showing that the virus does not have to come directly from the respiratory tract to be infectious.

Finally, the researchers tested whether the microscopic fibers of an inanimate object could carry infectious viruses. They treated the tissues with the flu virus, allowed them to dry, and then crumpled them in front of the automated particle size analyzer. The wrinkling of the fabrics released up to 900 particles per second in a size range that could be inhaled, they found. They were also able to infect cells from these particles released from paper tissue contaminated with the virus.

###

Reference: August 18, 2020, Nature’s communications.
DOI: 10.1038 / s41467-020-17888-w

The other co-authors of the article are Anthony Wexler of UC Davis and Nassima Gaaloul ben Hnia and Ramya S. Barre, all of the Icahn School of Medicine in Mount Sinai, New York.

The work was supported by a grant from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health.