Why Flu in Winter

Researchers discover why flu spreads primarily in winter.

Researchers may have discovered why flu infection spreads mainly during winter, according to a study published in PLoS Pathogens.

Lead author Peter Palese, Ph.D., a flu researcher who is professor and chairman of the microbiology department at Mount Sinai School of Medicine in New York, and colleagues, exposed guinea pigs to the flu virus. The guineas pigs became infected with the flu, and spread the infection.

The researchers "discovered that transmission was excellent at 41 degrees," but "declined as the temperature rose until, by 86 degrees, the virus was not transmitted at all."

In addition, they found that that the "virus was transmitted best at a low humidity, 20 %, and not transmitted at all when the humidity reached 80 %.