Featured Research

from universities, journals, and other organizations

New clues to how flu virus spreads

Date:
March 7, 2013
Source:
University of Maryland
Summary:
People may more likely be exposed to the flu through airborne virus than previously thought, according to new research. The study also found that when flu patients wear a surgical mask, the release of virus in even the smallest airborne droplets can be significantly reduced.

Routes of flu transmission include: 1) direct or indirect (e.g., doorknobs, keyboards) contact with an infected person, 2) contact via large droplet spray from a respiratory fluid (via coughs and sneezes), and 3) inhalation of fine airborne particles, which are generated by the release of smaller, virus-containing droplets via normal breathing and coughing.
Credit: Image courtesy of University of Maryland

People may more likely be exposed to the flu through airborne virus than previously thought, according to new research from the University of Maryland School of Public Health. The study also found that when flu patients wear a surgical mask, the release of virus in even the smallest airborne droplets can be significantly reduced.

"People are generally surprised to learn that scientists don't know for sure how flu spreads," says Donald Milton, M.D., Dr.P.H., who directs the Maryland Institute for Applied Environmental Health and led the study of influenza virus aerosols published in the journal PLOS Pathogens on March 7, 2013.

"Our study provides new evidence that there is nearly nine times more influenza virus present the smallest airborne droplets in the breath exhaled from those infected with flu than in the larger droplets that would be expected to carry more virus," explains Dr. Milton. "This has important implications for how we prevent the spread of flu."

Routes of flu transmission include:

1) direct or indirect (e.g., doorknobs, keyboards) contact with an infected person,

2) contact via large droplet spray from a respiratory fluid (via coughs and sneezes), and

3) inhalation of fine airborne particles, which are generated by the release of smaller, virus-containing droplets via normal breathing and coughing. The relative importance of these modes of influenza transmission has not been well understood, but is critical in devising effective interventions to protect healthcare workers and vulnerable people, such as infants and the elderly.

The Centers for Disease Control recommends that persons with influenza wear surgical masks to prevent transmission to susceptible individuals. Yet, this recommendation has been supported so far by only one study of mask impact on the containment of large droplet spray during influenza infection. Maryland's study is the first to provide data showing that using a surgical mask can reduce the release of even the smallest droplets containing infectious virus. For this reason, health care facilities should put surgical masks on those suspected of having influenza, and individuals with influenza can protect their families by wearing a mask.

Study Methods

Dr. Milton and his research team, including scientists from Harvard and Boston University Schools of Public Health and the University of Hong Kong, collected the exhaled breath from 38 flu patients and tested both the coarse (≥ 5 m) and fine (< 5 m) particles for the number of viruses using molecular methods. They found that the fine particles had 8.8 times more virus than the coarse particles (larger but still airborne droplets). They also tested the airborne droplets for "culturable" virus and found that virus was not only abundant in some cases, but infectious. However, there was a big range of how many viruses people put into the air -- some were undetectable while others put out over 100,000 every 30 minutes.

The researchers also tested the impact of wearing a surgical mask on the virus shedding into airborne droplets. Wearing a surgical mask significantly decreased the presence of virus in airborne droplets from exhaled breath. There was a 2.8 fold reduction in the amount of virus shed into the smallest droplets, and a 3.4 fold overall reduction in virus shed in both the coarse and fine and airborne particles.


Story Source:

The above story is based on materials provided by University of Maryland. Note: Materials may be edited for content and length.


Journal Reference:

  1. Donald K. Milton, M. Patricia Fabian, Benjamin J. Cowling, Michael L. Grantham, James J. McDevitt. Influenza Virus Aerosols in Human Exhaled Breath: Particle Size, Culturability, and Effect of Surgical Masks. PLoS Pathogens, 2013; 9 (3): e1003205 DOI: 10.1371/journal.ppat.1003205

Cite This Page:

University of Maryland. "New clues to how flu virus spreads." ScienceDaily. ScienceDaily, 7 March 2013. <www.sciencedaily.com/releases/2013/03/130307190637.htm>.
University of Maryland. (2013, March 7). New clues to how flu virus spreads. ScienceDaily. Retrieved August 28, 2014 from www.sciencedaily.com/releases/2013/03/130307190637.htm
University of Maryland. "New clues to how flu virus spreads." ScienceDaily. www.sciencedaily.com/releases/2013/03/130307190637.htm (accessed August 28, 2014).

Share This




More Health & Medicine News

Thursday, August 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Mini Pacemaker Has No Wires

Mini Pacemaker Has No Wires

Ivanhoe (Aug. 27, 2014) Cardiac experts are testing a new experimental device designed to eliminate major surgery and still keep the heart on track. Video provided by Ivanhoe
Powered by NewsLook.com
After Cancer: Rebuilding Breasts With Fat

After Cancer: Rebuilding Breasts With Fat

Ivanhoe (Aug. 27, 2014) More than 269 million women are diagnosed with breast cancer each year. Many of them will need surgery and radiation, but there’s a new simple way to reconstruct tissue using a patient’s own fat. Video provided by Ivanhoe
Powered by NewsLook.com
Blood Clots in Kids

Blood Clots in Kids

Ivanhoe (Aug. 27, 2014) Every year, up to 200,000 Americans die from a blood clot that travels to their lungs. You’ve heard about clots in adults, but new research shows kids can get them too. Video provided by Ivanhoe
Powered by NewsLook.com
Radio Waves Knock out Knee Pain

Radio Waves Knock out Knee Pain

Ivanhoe (Aug. 27, 2014) Doctors have used radio frequency ablation or RFA to reduce neck and back pain for years. But now, that same technique is providing longer-term relief for patients with severe knee pain. Video provided by Ivanhoe
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins