For years, researchers have struggled to discern whether temperature has anything to do with normal seasonal fluctuations in viruses—what the cold has to do with catching colds. And according to new research, Nature News reports, the old wives’ tale that the chilly winter air promotes sickness does turn out to be founded in fact.
Rhinoviruses cause the common cold and are the culprits behind most seasonal ailments. Lower temperatures, researchers from Yale University found, suppress the immune system’s ability to fight off these viruses in both mice and human airway cells.
In an attempt to solve the cold conundrum, Foxman and her colleagues studied mice susceptible to a mouse-specific rhinovirus. They discovered that at warmer temperatures, animals infected with the rhinovirus produced a burst of antiviral immune signals, which activated natural defenses that fought off the virus. But at cooler temperatures, the mice produced fewer antiviral signals and the infection could persist.
Humans likely follow the same patterns. The researchers grew human airway cells in the lab, then exposed them to rhinoviruses under different temperatures. Like the mice, the cells kept at a warm temperature were more likely to fend off the virus by undergoing programmed cell death, which limits the replicating virus’ spread throughout the body.
Thus, colds proliferate in winter when temperatures drop and cold air chills people’s upper respiratory tracts, giving the rhinovirus a chance to strike. While your parents were right to advise you to bundle up, the researchers point out to Nature that in science, nothing is ever so simple, and temperature is likely to be just one of several factors promoting colds in the wintertime.
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