Ever wonder why no matter how hard you try to stay healthy and get plenty of rest, you always seem to get a cold just as winter comes around. One factor of the common cold, recently discovered by Ellen Foxman of Yale University, may be out of your control; the weather. The article, Colder Viruses Thrive in Frosty Conditions, further explains how colder temperatures have been shown to be a reason for the flare up and spread of the common cold.
Ellen Foxman and her team studied rhinoviruses, a virus which is the main cause for seasonal colds, effects in the airways at cold and warm temperatures. Her team infected mice with a mouse rhinovirus and observed the effects for cold and warm temperatures. They found that at warmer temperatures, the infected mice’s immune system were able to produce a greater amount of antiviral signals. These signals activated the mice’s natural defenses which fought off the rhinovirus, thus leading to less chance of contraction of the common cold. In colder temperatures, the infected mice’s immune system produced less of these signals which allowed the rhinovirus infection to last longer, consequently allowing for a greater chance of getting the common cold.
Ellen Foxman and her team then performed the same experiment with human airway cells as they did on the mice but used a rhinovirus that is found in humans. The human airway cells were grown in a lab and exposed to cold and warm conditions. The results they found were similar to the changes they noticed in the mice. In warmer temperatures, the rhinoviruses did not seem to thrive and even appeared to undergo cell death to limit the spread of infection of the common cold. The team also discovered that in the upper airways that the colder temperature seemed to weaken the body’s natural defenses and thus allowed the spreading of rhinoviruses resulting in a cold. The team was also able to conclude why rhinoviruses were able to replicate better in the upper airways. The upper airways are colder in temperature in comparison to the respiratory tract as a whole, therefore in the winter when continually breathing in cold air, the rhinoviruses are able to replicate and cause the long lasting common cold. They also noticed that rhinoviruses tended to replicate less in the lungs of the respiratory tract, because the lungs are warmer in temperature compared to the upper airway, and thus the rhinoviruses are not able to thrive.
In conclusion, Ellen Foxman and her team of Yale University were able to determine one factor that can explain why we get the common cold during the winter season. They examined the spread of rhinoviruses in mice and in human airway cells in cold and warm temperatures to determine its effects. They discovered that rhinoviruses replicate better in the colder temperatures because our defense system is weakened due to these cooler temperatures, thus resulting in a cold. In warmer temperatures, our bodies tell the infected cells to die to prevent infection. Thus this is one factor that explains why no matter how hard you may try to prevent a cold in the winter it may just be out of your control.