Featured Research

from universities, journals, and other organizations

Why is the flu more common during the winter season?

Date:
December 4, 2012
Source:
Virginia Tech (Virginia Polytechnic Institute and State University)
Summary:
Environmental engineers have shown for the first time the relationship between the influenza A virus viability in human mucus and humidity over a large range of relative humidities, from 17 percent to 100 percent.

Influenza, commonly known as the flu, has distinct transmission patterns around the world. In temperate regions, influenza's occurrence peaks during the winter season, while in some tropical regions, the disease's occurrence tends to correspond with the rainy season.

Related Articles


Linsey Marr, associate professor of civil and environmental engineering at Virginia Tech, and her colleagues, Wan Yang, of Blacksburg, Va., one of her doctoral students, and Elankumaran Subbiah, a virologist in the biomedical sciences and pathobiology department of the Virginia-Maryland Regional College of Veterinary Medicine, measured the influenza A virus survival rate at various levels of humidity.

Their study presents for the first time the relationship between the influenza A virus viability in human mucus and humidity over a large range of relative humidities, from 17 percent to 100 percent. They found the viability of the flu A virus was highest when the relative humidity was either close to 100 percent or below 50 percent. The results in human mucus may help explain influenza's seasonality in different regions.

"We added flu viruses to droplets of simulated respiratory fluid and to actual human mucus and then measured what fraction survived after exposure to low, medium, and high relative humidities," said Marr.

At low humidity, respiratory droplets evaporate completely and the virus survives well under dry conditions. But at moderate humidity, the droplets evaporate some, but not completely, leaving the virus exposed to higher levels of chemicals in the fluid and compromising the virus' ability to infect cells.

In a past study also conducted by Marr, Yang, and Subbiah, published in United Kingdom's Journal of the Royal Society Interface, the researchers collected samples from a waiting room of a health care center, two toddlers' rooms and one babies' area of a daycare center, as well as three cross-country flights. Findings showed the average concentration was 16,000 viruses per cubic meter of air, and the majority of the viruses were associated with fine particles, less than 2.5 micrometers, which can remain suspended for hours.

Possible explanations for the seasonality of the flu have been investigated, such as the return of kids to school, people spending more time indoors in the winter, and lower light levels that affect the immune system, but there is no agreement on them, said the NSF CAREER award recipient.

The researchers found humidity could explain the seasonality of influenza by controlling the ability of viruses to remain infectious while they are in droplets or aerosols. The viruses survived best at low humidity, such as those found indoors in the winter, and at extremely high humidity. Humidity affects the composition of the fluid, namely the concentrations of salts and proteins in respiratory droplets, and this affects the survival rates of the flu virus.


Story Source:

The above story is based on materials provided by Virginia Tech (Virginia Polytechnic Institute and State University). Note: Materials may be edited for content and length.


Cite This Page:

Virginia Tech (Virginia Polytechnic Institute and State University). "Why is the flu more common during the winter season?." ScienceDaily. ScienceDaily, 4 December 2012. <www.sciencedaily.com/releases/2012/12/121204162125.htm>.
Virginia Tech (Virginia Polytechnic Institute and State University). (2012, December 4). Why is the flu more common during the winter season?. ScienceDaily. Retrieved November 20, 2014 from www.sciencedaily.com/releases/2012/12/121204162125.htm
Virginia Tech (Virginia Polytechnic Institute and State University). "Why is the flu more common during the winter season?." ScienceDaily. www.sciencedaily.com/releases/2012/12/121204162125.htm (accessed November 20, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Thursday, November 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

UN Says It Will Scale Up Its Ebola Response

UN Says It Will Scale Up Its Ebola Response

AFP (Nov. 20, 2014) UN Resident Coordinator David McLachlan-Karr and WHO representative in the country Daniel Kertesz updated the media on the UN Ebola response on Wednesday. Duration: 00:51 Video provided by AFP
Powered by NewsLook.com
Takata Offers "sincerest Condolences" To Victims of Malfunctioning Airbag

Takata Offers "sincerest Condolences" To Victims of Malfunctioning Airbag

Reuters - US Online Video (Nov. 20, 2014) U.S. Congress hears from a victim and company officials as it holds a hearing on the safety of Takata airbags after reports of injuries. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Obesity Costs Almost As Much As War And Terrorism

Obesity Costs Almost As Much As War And Terrorism

Newsy (Nov. 20, 2014) The newest estimate of the cost of obesity is pretty jarring — $2 trillion. But how did researchers get to that number? Video provided by Newsy
Powered by NewsLook.com
Calling All Men: Here's Your Chance to Experience Labor Pains

Calling All Men: Here's Your Chance to Experience Labor Pains

Reuters - Light News Video Online (Nov. 20, 2014) Chinese hospital offers men a chance to experience the pain of child birth via electric shocks. Sharon Reich reports. Video provided by Reuters
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:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

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