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, Dr. Magdy Badran says.
Exposure to cold and dry air may adversely impact the body's immune system and make it harder for the body to fight off germs.
The Common Cold
Rhinoviruses are the most common cause and are responsible for more than half of all colds and cold-like illnesses.
The coronavirus is the cause of about 20% of colds. There are more than 30 kinds, but only three or four affect people.
Respiratory syncytial virus and parainfluenza virus causes 20% of colds. They sometimes lead to severe infections, like pneumonia, in young children.
Temperatures below 37° Celsius may allow rhinoviruses to replicate more efficiently. The optimal temperature for rhinovirus replication is between 33-35°C.
The temperature inside the nasal cavity is approximately 33°C, which may make it an ideal breeding ground for rhinoviruses.
Rhinovirus infections typically result in mild cold-like symptoms. However, rhinoviruses can also cause more severe illnesses, such as bronchitis and pneumonia, in people with weakened immune systems.
Rhinoviruses typically spread through direct person-to-person contact, the air as small droplets, or aerosols, which people then inhale.
Once inhaled, the rhinovirus attaches itself to the cells inside the nasal passages. It then begins to replicate itself, spreading more virus particles throughout the upper respiratory tract. Decreases in both temperature and humidity over 3 days increased the risk of rhinovirus infections.
The Reason for The Season: Why Flu Strikes in Winter
Influenza viruses, which cause the flu, may also survive and spread more easily in cold and dry air. A common misconception is that the flu is caused by cold temperatures. However, the influenza virus is necessary to have the flu, so cold temperatures can only be a contributing factor.
The influenza virus may survive better in colder, drier climates. During the winter, people spend more time indoors with the windows sealed, so they are more likely to breathe the same air as someone who has the flu and thus contract the virus.
Days are shorter during the winter, and lack of sunlight leads to low levels of vitamin D and melatonin. This compromises our immune systems, which in turn increases the chance to get an influenza virus.
Breathing in cold and dry air causes the blood vessels in the upper respiratory tract to narrow to conserve heat. This may prevent immune cells from reaching the mucous membrane, making it harder for the body to fight off germs.
Indoor air relative humidity is lowest during the winter. Thus, exposure to cold air outside or dry air inside during the wintertime may increase influenza virus transmission and potentially trigger a flu season.
The nasal mucociliary clearance transports the mucous layer that covers the nasal epithelium towards the nasopharynx by ciliary beating.
Its function is to protect the respiratory system from damage by inhaled substances. Phagocytes are cells that protect the body by ingesting harmful foreign particles, germs, and dead or dying cells.
Cooling of the nasal epithelium through inhalation of cold air inhibits mucociliary clearance and may limit phagocytosis by immune cells in the upper airways. Inhalation of dry air for a 30-min period was found to slow mucociliary clearance.
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Two Egyptian Men Try To Avoid Rains[/caption]
Mechanisms of Heat Loss
The body loses heat through the evaporation of water from your skin if it is wet (sweating). If your clothing is wet, you will also lose somebody's heat through evaporation and respiration (breathing) when the body temperature is higher than 37°C.
During intense exercise, the body loses 85% of its heat through sweating. Radiation, this normal process of heat moving away from the body usually occurs in air temperatures lower than 20°C. The body loses 65% of its heat through radiation.
Conduction, such as heat loss from sleeping on the cold ground. The body loses about 2% of its heat through air conduction. However, water causes more heat loss from the body than air does, so heat can be lost from the body very quickly when it is placed in cold water.
Convection, similar to sitting in front of a fan of having the wind blow on you. The body loses 10% to 15% of its heat through convection. Heat loss through evaporation and respiration increases in dry, windy weather conditions.
Toes, fingers, ears, and nose are at greatest risk because these areas do not have major muscles to produce heat.
Besides, the body preserves heat by keeping the internal organs warm; thus, reducing the flow of blood to the extremities under cold conditions.
Hands and feet tend to get cold more quickly than the body because they lose heat more rapidly since they have a higher surface-area-to-volume ratio, and they are more likely to be in contact with colder surfaces than other parts of the body.
Wet clothing greatly increases heat loss through conduction and evaporation.
Hypothermia
Hypothermia is a physical condition that occurs when the body's core temperature falls below a normal 37° C to 35° C or cooler.
Hypothermia is often caused by exposure to cold weather or immersion in cold water.
When the balance between the body's heat production and heat loss tips toward heat loss for a prolonged period, hypothermia can occur.
Accidental hypothermia usually happens after cold temperature exposure without enough warm, dry clothing for protection.
Heat loss in cold, wet weather increases the risk of hypothermia.
Swimming or sitting in cool or cold water can cause the body to lose heat very quickly and increase the risk of hypothermia.
The immune response decreases during hypothermia, which can result in an increased infection rate. Hypothermia also results in impaired coagulation. Hypothermia can lead to prolonged action of anesthetic drugs.
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Girl Gets Warm in The Cold Weather[/caption]
Elderly people, homeless people, and those under the influence of alcohol or drugs are particularly vulnerable to hypothermia. Children and people with certain health disorders are also susceptible.
Hypothermia can occur quickly (within a few hours) or gradually over days and weeks depending on a person's age, overall health, and environmental conditions.
Left untreated, severe hypothermia may fail the heart and respiratory system, unconsciousness and possibly death. About 600 people in the U.S. die of hypothermia each year.
Tips to Avoid Getting Sick During This Winter
The best way to prevent common cold infections is to practice good hygiene by washing your hands frequently and avoiding touching your nose, eyes, and mouth.
Also, when possible, avoid close contact with people who have colds or other upper respiratory infections. Try eating foods that are high in vitamin D, such as fatty fish, mushrooms, and eggs.
Getting plenty of sleep. Always sneezing and coughing into clean tissues; if no tissue is available, it is better to use an elbow rather than the hands. Not sharing foods, drinks, crockery, and utensils with people who have a cold or the flu.
Try staying hydrated, hydration plays a crucial role in regulating your body temperature. As your body reacts to the chill, you're less likely to feel thirsty, even when you need water—that's why it can be deceptively easy to get dehydrated in frigid environments.
Drinking a hot beverage won't warm up your whole body, but is a good way to encourage yourself to stay hydrated in cold climates.
The best way to protect against the flu is by having an annual vaccination, as this helps the body to build up the immune system so that it can fight off the virus more quickly.
In cold water, conserving body heat is essential for survival. Dressing properly is one of the keys to being healthy in a cold climate.
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