Pakistan News Service

Monday Dec 22, 2014, Safar 29, 1436 Hijri
Logo Logo
LATEST :
Pakistan News Home -> Health -> News Details

Why flu virus infects mostly in winter

11 December, 2012

ISLAMABAD: Scientists have discovered a possible reason why the flu virus is seasonal and tends to infect people mostly in the winter.

They found that the virus survived best at low humidity, such as those found indoors in the winter, and at extremely high humidity.

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.

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

"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.

End.

 What do you think about the story ? Leave your comments!

Heading (Optional)
Your Comments: *

Your Name:*
E-mail (Optional):
City (Optional):
Country (Optional):
 
 
Field marked(*) are mandatory.
Note. The PakTribune will publish as many comments as possible but cannot guarantee publication of all. PakTribune keeps its rights reserved to edit the comments for reasons of clarity, brevity and morality. The external links like http:// https:// etc... are not allowed for the time being to be posted inside comments to discourage spammers.

  Speak Out View All
Imran - Qadri long march
Artilce 6 and Musharraf Trail
  Quick Vote Show Results
Question: "In view of the current situation do you think Talks with Taliban should take place only within the ambit of Article 4 of Objectives Resolution that defines our Common Purpose i.e. PM/ President down to all Pakistanis to work till we achieve the rights of Democracy, Freedom, Tolerance and Social Justice for all Pakistanis:"
Yes
No
 
Candid Corner
Exclusive by
Lt. Col. Riaz Jafri (Retd)
LHC tells Sharif family to pay Rs 3.5bn mark-up on loan
Osama's killer comes forward to reveal his name
Suggested Sites