Mucus Is Not Just For Swallowing Anymore


Dave, do you know that our mucus actually helps spread the flu virus? That's a surprise! I knew that our mucus protects us from certain microbial invaders, but help the flu virus? No.

So, researchers had set out to uncover why the flu virus remains infectious for extended periods in the air. This is interesting because previous studies have shown that flu virus sprayed into the air in the lab degraded faster when the humidity was higher. That's right, the virus survives better in dry versus wetter conditions. So, this told us how the virus behaves inside a heated building in the winter, except the virus doesn't normally get into the air on its own. It's expelled by people who are coughing or sneezing.

That's why in this study, scientists working with the swine flu from the two thousand nine pandemic, combined the virus with human airway secretions, and then sprayed it into a test chamber. No matter the condition of the test chamber, dry indoor to tropical, wet air, the virus remained suspended for one hour, about the amount of time for old air to move out and to cycle in new air in a typical building.

This means that virus in the mucus secretions is protected and less vulnerable to environmental changes. So, then how do you protect yourself from the flu? The annual flu shot remains the most effective.

Treating or filtering re-circulated air inside buildings could help along with increases in air exchange inside buildings. The bottom line is the flu is not going away and we need multiple approaches to control this virus which kills nearly fifty thousand Americans during epidemic years.

More Information

Influenza Virus Infectivity Is Retained in Aerosols and Droplets Independent of Relative Humidity
Pandemic and seasonal influenza viruses can be transmitted through aerosols and droplets, in which viruses must remain stable and infectious across a wide range of environmental conditions. Using humidity-controlled chambers, we studied the impact of relative humidity on the stability of 2009 pandemic influenza A(H1N1) virus in suspended aerosols and stationary droplets...

Flu virus is protected by mucus when airborne regardless of humidity
Virginia Tech and University of Pittsburgh researchers have discovered that when a person with the flu coughs or exhales, mucus and other airway secretions are expelled and appear to protect the virus when it becomes airborne, regardless of humidity levels...

Estimating Seasonal Influenza-Associated Deaths in the United States
Seasonal influenza-related deaths are deaths that occur in people for whom seasonal influenza infection was likely a contributor to the cause of death, but not necessarily the primary cause of death...