Why Influenza Spreads in Winter Only

A study in guinea pigs suggests that human influenza viruses are shed longer at low temperatures and that the infection is spread more easily under cold, dry conditions.

In the Northern Hemisphere, influenza epidemics spread only during the winter, when weather conditions are cold and sometimes dry. However, the precise reason for this seasonal pattern has remained elusive. Now, researchers have evaluated the effects of temperature and relative humidity on the transmission of influenza virus A among guinea pigs. Like humans, these animals are susceptible to influenza viruses and spread the infection easily.

Pairs of infected and uninfected animals were housed together in an environmental chamber with controlled temperature and humidity under conditions that facilitated virus spread. At 20°C, transmission was very efficient at relatively low humidity levels (20% or 35%). When the temperature was dropped to 5°…

Reviewing Author

Thomas Glück, MD

Disclosures

Editorial BoardsConsilium Infectiorum by InfectoPharm, Infection

Thomas Glück, MD

Disclosures

Editorial BoardsConsilium Infectiorum by InfectoPharm, Infection