A new study answers the old question, why flu is common in winters
10 th March 2008—Frequency of occurrence of flu in winter season is more than any other season of the year - a fact that has baffled scientists for years.
US researchers at the National Institutes of Health carried out a study to reveal the causes for high occurrence of flu in winters.
According to their findings, influenza viruses are protected in winters by a fatty substance, which becomes hard. These viruses coat themselves inside this substance. This protects them from extreme cold temperatures. This fatty material resembles a butter coating and melts only when in the respiratory tract. Due to this, it allows the virus to infect cells in the body. Researchers used a nuclear magnetic resonance imaging for viewing outer coat of flu viruses.
Where was the Study Carried Out?
The study was carried out at one of the National Institutes of Health, known as the National Institute of Child Health and Human Development (NICHD).
Joshua Zimmerberg, who led the study, said, “Like an M&M in your mouth, the protective covering melts when it enters the respiratory tract.”
He further said, “It's only in this liquid phase that the virus is capable of entering a cell to infect it.”
According to the director of NICHD, Duane Alexander, these findings could lead to more ways for prevention and treatment of flu infection.
He said in a statement, “The study results open new avenues of research for thwarting winter flu outbreaks.”
The statement further read, “Now that we understand how the flu virus protects itself so that it can spread from person to person, we can work on ways to interfere with that protective mechanism.”
How is flu spread?
Flu or influenza is spread though small droplets, which scatter in the air due to coughing, sneezing, or even talking with other persons. These viruses also settle on surfaces and enter the body when person contacts these surfaces with fingertips and then touches his mouth or nose.
Flu viruses cannot multiply on their own. They have a membrane-like coating on the outer side that they combine with the victim cell. They infect a living cell and inject genetic material into it. The flu virus takes the help of lipids such as cholesterol from the cells to make a membrane for infecting other cells.
Hemagglutinin is a protein, which resides inside a warm cell and the common vaccines are generally made for this protein. However, at cooler temperatures, this protein starts ordering process, which is similar to crystallization.
When the weather is warm, the protective coating melts and the viruses are destroyed, unless the viruses have already infected a human being or animal.
About this hemagglutinin process, Joshua Zimmerberg said, “It solidifies gradually all the way down from 40 degrees Celsius (104 degrees F) down to 4 degrees C (39 degrees F).”
He further said, “I believe that this gradualness lets it exist at every temperature.”
Unless the temperature is very low, this protective coating helps the virus to spread. This is the reason why winter is the season for influenza. The findings of this study could help scientists find more ways to add to the existing list of anti-viral drugs for eradicating influenza. | 
