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There is A Scientific Reason That Cold Weather Could Cause Colds

The rhinovirus that most commonly causes colds likes chillier temperatures, where the host’s immune system doesn’t fare so well

https://www.smithsonianmag.com/smart-news/there-scientific-reason-cold-weather-could-cause-colds-180953817/

(Paul Linse/Corbis)

By Marissa Fessenden

SMITHSONIANMAG.COM

JANUARY 6, 2015

If you’d like to get technical, a cold can be called nasopharyngitis, rhinopharyngitis or acute coryza. Often, it’s an infection with rhinovirus, but more than 200 other viruses can cause the coughing, sore throat, runny nose and sneezing that we call the common cold. Since colds have long been associated with the chilly, wet weather of winter, that’s likely where they picked up their easily recognized name.

More recently, humans have recognized that viruses are the true cause of colds and speculated that the close contact with others when we are forced indoors by the weather might be to blame for the cold-season association. But the old folk wisdom might have some truth: Researchers have just found a way to explain how getting cold might give you a cold.

Rhinoviruses, which are the most common cause for colds, are better able to reproduce at temperatures just below the body’s 98.6 degrees Fahrenheit. To find out why, a group of scientists studied how a mouse-adapted cold virus fared in rodent lungs and nasal cavities, reports Monte Morin for the Los Angeles Times. He writes:

What they discovered was that when a virus invaded warmer cells, the host cells produced significantly more interferons – proteins that "interfere" with the spread of a virus by warning healthy cells of its presence and setting off an immune response.

In the cooler nasal cavity cells, this warning system was less efficient however, and allowed the virus to spread more easily.

Previously, researchers had discovered that cold viruses prefer the cooler temperatures of the nose, but the new study emphasizes the influence of the host’s response on the virus’s ability to replicate. The researchers published their findings in the Proceedings of the National Academy of Sciences.

The discovery "could explain why the rhinovirus causes colds and is less able to cause more serious lung infections, like influenza does," says Jonathan Bell, a virologist at the University of Nottingham and not involved in the study, told the BBC. But more immediately relevant for those about to venture outdoors, we now know that covering your nose might actually help it stay cold-free, in more than one way.

https://www.medicalnewstoday.com/articles/323431.php#takeaway

Effect of cold weather on the immune system

Less vitamin D during winter months can affect the immune system.

Many researchers believe that exposure to cold weather can adversely affect a person's immune response, making it harder for the body to fight off infections. Reasons for this may include:

Reduced vitamin D levels. During the winter months, many people get less vitamin D due to reduced sun exposure. Research suggests that vitamin D plays an essential role in maintaining the immune system.

Spending more time indoors. People tend to spend more time indoors during winter months, and viruses spread more when people are close to each other.

Lower temperatures may affect immune response. A 2015 study found that exposing airway cells taken from mice to lower temperatures decreased the immune response of the cells against a mouse-adapted rhinovirus.

Blood vessel narrowing. Breathing in cold and dry air causes the blood vessels in the upper respiratory tract to narrow to conserve heat. This may prevent white blood cells from reaching the mucous membrane, making it harder for the body to fight off germs.

Takeaway

Viruses, such as rhinoviruses and influenza, cause colds and the flu, not the weather. However, exposure to cold weather can increase a person's risk of contracting a virus.

Research suggests that these viruses may survive and reproduce more effectively at colder temperatures, making it easier for them to spread and infect more people. Cold weather may also reduce the immune response and make it harder for the body to fight off germs.