Scientists Probe Why the Winter Season is Associated with Catching a Cold

Even though conventional wisdom establishes a link between colds and the winter season, the phenomenon has been a scientific mystery simply because there is no research to prove a connection between the two.

Now, new research with animals might support that conventional wisdom. A study suggests that decreases in internal body temperature after exposure to cold could also decrease the immune system's ability to fight the rhinovirus, a type of virus that is the cause of the common cold, Fox News reported.

Akiko Iwasaki, the co-author of the study and also a professor of immunobiology at Yale University, explained: "It has been long known that the rhinovirus replicates at the cooler temperature, around 33 Celsius (91 Fahrenheit) compared to the core body temperature of 37 Celsius (99 Fahrenheit)" Then he added that the reason for virus's cold temperature preference was unknown and continued "Much of the focus on this question has been on the virus itself. However, virus replication machinery itself works well at both temperatures, leaving the question unanswered."

In order to find an answer to the question, researchers used mouse airway cells as a model and discovered that at cooler temperature found in the nose, the immune system of the host was unable to induce defense signals to block viruses from multiplying.

Researchers divided the mouse airway cells into two groups. The first group was kept at 99F (the core temperature of the lungs), while the other group was kept at 91F (the temperature of the nose). Even though the fluctuations in internal body temperatures did not have a direct impact on the virus itself, they did have an indirect impact on the body's immune response to the virus. Cells that were kept at warmer temperatures showed a stronger immune response to the virus compared to the cells kept at cooler temperatures.

When asked about the effect of outdoor temperature on this new finding, Iwasaki said: "By inhaling cold air from outside, the temperature inside the nose will likely decrease accordingly, at least transiently. Therefore, an implication of our findings is that the cooler ambient temperature would likely increase the ability of the virus to replicate well and to develop a cold."