10/07/2024
Cold weather and the “cold”
While cold weather does not directly cause a cold, the viruses that cause colds may spread more easily in lower temperatures. Various steps can help a person avoid getting sick during the colder months.
Doctors are frequently told that “my child got a cold because he/she was playing bare feet” – the short answer is that you do not catch a cold by playing bare feet. The cold or flu virus cannot enter through the feet!
What cold air does produce when passing through the nose is a vasoconstriction of the mucosa (the opposite of we said a virus produces) and a decrease in the immune response (the natural cleansing mechanism and the activity of white blood cells decreases). Both situations can favour the entry of viruses and the development of the disease.
That is, when we are breathing cold air, we can catch a cold if someone nearby is sick or by touching contaminated objects, but not by going out with wet hair, spending the morning in damp socks or walking barefoot all day on the marble floor.
There are studies that show that cooling the body surface, wearing damp clothes or having wet hair does not increase the risk of infection, even when the virus has been injected directly into the nose.
Rhinoviruses and the common cold:
Millions of people develop the common cold each year. On average, adults get two or three colds a year. Many viruses can cause the common cold. Rhinoviruses are the most common cause and are responsible for around half of all colds and cold-like illnesses. Rhinoviruses typically spread through direct person-to-person contact or inhaling small droplets in the air. These droplets are often known as aerosols.
Once inhaled, the rhinovirus attaches itself to the cells inside the nasal passages. It then replicates itself, spreading more virus particles throughout the upper respiratory tract.
Symptoms of the common cold:
• a sore throat
• a runny nose
• coughing
• sneezing
• high temperature
• muscle aches
• headaches
• a loss of taste or smell
However, rhinoviruses can also cause more severe illnesses, such as bronchitis and pneumonia, in people with weakened immune systems.
Effect of cold weather on viruses:
Exposure to cold weather does not make people more susceptible to common colds.
Some research suggests that rhinoviruses may replicate more efficiently at temperatures lower than 37°C, the average core body temperature in humans. The temperature inside the nasal cavity is approximately 33°C which may make it an ideal breeding ground for rhinoviruses.
However, this does not confirm that lower outside temperatures increase the risk of rhinovirus infection. Most research on rhinoviruses has primarily focused on examining how differences in body temperature affect the virus’s ability to reproduce.
One study examined whether or not variations in temperatures and humidity led to a higher risk of rhinovirus infection. The researchers found that decreases in temperature and humidity over 3 days increased the risk of rhinovirus infections in participants.
In the same study, researchers found that most infections occurred in temperatures at zero degrees and below.
The flu:
While cold weather may not exacerbate rhinoviruses, cold, dry air, as is common in winter, can assist the transmission of influenza viruses.
During colder months, people may also spend more time indoors. If these spaces do not have adequate ventilation, people may have a greater risk of breathing in aerosols from others with common colds.
Effect of cold weather on 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, many people get less vitamin D due to reduced sun exposure. Vitamin D plays an essential role in maintaining the immune system.
• 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 germs.
Preparing for cold season:
Some ways to avoid getting sick during the winter include:
• ensure adequate nutrition to include vitamins and minerals from fruits and vegetables
• getting plenty of sleep
• staying hydrated
• washing hands regularly
• always sneezing and coughing into clean tissues
• not sharing foods, drinks, crockery, and utensils with people who have a cold or the flu
Summary
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
