A study published in the in the journal Nature Communications has confirmed that influenza viruses can spread through many non-respiratory particles.
The researchers say that airborne transmission does not necessarily occurs through respiratory droplets. The research says that transmission which is not spread by sneezing, talking or coughing, needs further investigation, and “has profound implications for how we interpret laboratory experiments as well as epidemiological investigations of outbreaks”.
“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 Professor William Ristenpart from the University of California, Davis in the US.
The researchers have identified several different routes through which influenza virus can spread:
- Droplets exhaled from the respiratory tract
- Secondary objects like door handles or used tissues, also called fomites, can also spread infections.
However, the current research has not confirmed which of the above two routes is the most important one.
Different strains of influenza virus or other respiratory viruses may spread trough different routes. In the new study, the researchers looked at whether tiny, non-respiratory particles they call “aerosolised fomites” could carry influenza virus between guinea pigs.
Using an automated particle sizer to count airborne particles, they found that uninfected guinea pigs give off spikes of up to 1,000 particles per second as they move around the cage.
The researchers found particles given off by the animals’ breathing were at a constant, much lower rate.
Immune guinea pigs with influenza virus painted on their fur could transmit the virus through the air to other, susceptible guinea pigs. This confirms that respiratory tract does not always involved in spreading the virus, and there are other routes through which the virus spreads.
The researchers then turned their attention on inanimate objects. Facial tissues was one such object. Facial tissues were treated with influenza virus. Once it dried out, it was put right in front of the automated particle sizer.
Crumpling the tissues released up to 900 particles per second in a size range that could be inhaled, the researchers found.
They were also able to infect cells from these particles released from the virus-contaminated paper tissues.