Common airborne viruses travel further, remain viable longer
When your mum told you to cover your mouth when you cough or sneeze, she was teaching you to prevent the infection of other people. New research findings are reinforcing that advice because the risk of infection by sharing germs this way is a lot higher than we thought. The current medical consensus is that if you sneeze or cough within about 1–2m of someone, and they breathe it in, or make oral contact with bacterial cells within a number of seconds or so, there is a chance of infection spreading to them. What if we have been underestimating the potential spread and lifetime of infectious agents?
It turns out that you can actually spread germs with a cough or sneeze further, and they remain viable for far longer than most people think. It is an unpleasant thought, and it reinforces the importance of preventing infection. This realisation also has considerable impact for the staff of hospitals and centres that care for people with compromised immune systems.
The science is in. A team of researchers from Queensland University of Technology, led by Professor Lidia Morawska, Director of the International Laboratory for Air Quality and Health and Professor Scott Bell from QIMR Berghofer Medical Research Institute and The Prince Charles Hospital, both in Brisbane Australia, have tested the theory and found that when a person coughs of sneezes, their germs travel along with any air current as far as 4 metres. They also found that the bacterial cells stay live in the air for up to 45 minutes.
In this study, airborne particle researcher, Professors Lidia Morawska, Scott Bell, and their interdisciplinary team examined the airborne transmission of the common bacterial pathogen (germ) Pseudomonas aeruginosa among patients with cystic fibrosis (CF). People with CF have weakened immune systems, and so the results of this study could influence the guidelines for managing their care environments.
Data resulting from this study challenge current CF infection control practices of separating patients by 1–2 m to prevent cross-infection by respiratory bacteria. This suggests that hospital and care centre management need to re-examine current infection control practices within the CF community.
The research team used two validated aerosol sampling systems to measure the viability of P aeruginosa in droplets from people sneezing or coughing. They demonstrated that patients with CF produce cough aerosols containing viable organisms that are capable of travelling up to 4 m and surviving in the air for up to 45 min.
What do we do about it?
There are a few important impacts for members of the public from this research. The first is to learn a new rule of thumb about the spread of respiratory pathogens (germs). If you are carrying an infection, be aware that you could be spreading it further than you realise when you sneeze or cough. In addition, flu-carrying droplets from your sneeze or cough are also likely to be able to remain alive and viable for 45 minutes.
Prevention is far better than cure. Spread the word, not the flu.
To contact the researchers, go to the International Laboratory for Air Quality and Health.
For more information about the study, consult the original published findings:
Viability of Pseudomonas aeruginosa in cough aerosols generated by persons with cystic fibrosis PLOS ONE | DOI:10.1371/journal.pone.0158763 July 7, 2016.
Find out more about research at QUT.
This research was supported by The CF Foundation (USA) and the TPCH Foundation QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia; The Prince Charles Hospital and Chermside, Queensland Australia; and the Royal Children’s Hospital, Herston, Queensland, Australia.