Does Winter Cause The Flu? Microbiologists Discover Reason Why The Flu Virus Thrives In Winter

January 1, 2008 — Virologists investigating transmission of the flu virus found that it is more likely to spread at colder temperatures. The dry, cold conditions pull moisture out of droplets released by coughs and sneezes, which allows the virus to linger in the air. Additionally, cold, low humidity air dries out the nasal passages and makes virus transmission more likely. This contradicts the long-held view that the flu spreads because the immune system is less active during the winter.

When Mom or Grandma tells you to bundle up in winter, you might catch a cold or flu, she may be right. New scientific experiments have now proven what we all just assumed, that flu is more common in winter.

If you have had the flu, you know how awful it feels. "Incredible body pain, muscle aches, sore joints, difficulty walking," said Samira Mubaraka, who has had the flu twice.

We all know influenza is more common in winter. But researchers have not known why. Virologist doctor Peter Palese has been studying the effects of heat and cold on the flu virus. He found that at higher temperatures, the flu virus didn't spread, but at colder temperature it did.

"The virus is probably more stable in cold temperature, so it hangs in the air much longer," Dr. Palese told Ivanhoe.

Allowing it to spread easier. Here's how -- when we cough or sneeze, microscopic droplets of water and the virus enter the air. Dry, cold conditions dry out the droplets, helping the virus linger in the air. The dry air also dries out nasal passages, which helps the virus stick.

"Cold dry air going over your nasal mucosa gets cracks in our airways and that allows virus to get in more easily," Anice Lowen, researcher at Mt. Sinai School of Medicine told Ivanhoe.

And as we head into colder temps -- doctors say although we can't control, we can get a flu shot to try and prevent it.

WHAT IS THE FLU? The flu is caused by the influenza virus, which targets the respiratory tract by binding to the surface of cells. Then the virus releases its genetic information into the cell's nucleus to replicate itself. When the cell dies, those copies are released into the body, infecting other cells. Flu symptoms are unpleasant, but not life-threatening by themselves.

However, the flu weakens the immune system, making the body vulnerable to more serious infections, such as pneumonia. Because the flu is caused by a virus -- as opposed to bacteria -- antibiotics are not an effective treatment. Both the flu and the common cold are best treated by bed rest, consuming lots of fluids, and taking over-the-counter medication to ease symptoms until the virus runs its course.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Note: This story and accompanying video were originally produced for the American Institute of Physics series Discoveries and Breakthroughs in Science by Ivanhoe Broadcast News and are protected by copyright law. All rights reserved.