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Cold and flu: 5 reasons to get sick in the winter

Холод и простуда: 5 причин болеть зимойIn the yard snow, ice and frost. People are wrapped in down jackets and fur coats, vitamins, drink, smeared different ointments nose — and still get sick. That power has the cold over us? Why winter is the citizens get the flu more often, than our weaknesses? We understand why most people lose the battle cold and over and over again that a cold winter in a row.

Cold air: blow to the nose

The human nose is a cavity with caves, whose walls are completely covered with slime. The protective substance produced by the mucosa cells and plays an important role in the body’s defense against infectious attacks from the outside. When viruses and bacteria enter the nose, they are deposited in a sticky viscous mucus. Ciliated cells that are in constant motion, smartly driven mucus to the nasal passages, where it enters the oropharynx and into the stomach. There are all harmful microorganisms successfully neytralizuya hydrochloric acid.

When we inhale cold air, the mucus becomes more viscous and does not move as fast. As a result, the viruses and bacteria get more time to try to penetrate into the cells of our body.

In addition, inhalation of cold air occurs reflex vasoconstriction. As a result, the bloodstream deteriorates and white blood cells, infection-fighting, is getting smaller. In addition, the nose tissue get less power, and thus immune cells will lack resources to fight the invaders. So, normally, if the virus managed to break through the protective mucous layer and into the human tissue, it is met by phagocytes — immune cells-eaters aliens. But the cold air reduces their activity and the virus gets another chance for a successful attack. The cold also leads to increased insulin resistance and, consequently, to increase the level of sugar in the blood and result in hyperglycemia.

The cold can really kill. Scientists believe that up to 10% of cases of death of newborns due to a flu, pneumonia or sudden infant death syndrome, actually been caused by cold injury.

So, in the cold, the body becomes more vulnerable to infection, are more susceptible to it. Therefore, scientists say that the epidemic of upper respiratory infections in the cold season can be explained by the conversion of asymptomatic to symptomatic infections. This means that familiarity with the infection, which in warm time of the year would remain for us unnoticed, on a cold manifests itself in the form of a cold.

A comfortable temperature for the virus

If our body at low temperatures is not good, cold viruses, on the contrary, the expanse. Most rhinoviruses are generally more comfortable with herself it at low temperatures (33-35°C). The higher the temperature (and body), the higher the probability that the rhinoviruses can not reproduce and generally make the infected cells of a host organism to commit apoptosis (self-destruction).

Such dependence is characteristic of some other viruses. Scientists have observed the people in the coldest region of the planet — in Antarctica. The staff of the Antarctic stations come there for the winter, spends 9 months in the harsh conditions and went back. It turned out that during his stay at the station, the concentration of virus DNA Epstein-Barr in the saliva of explorers increases from 6% up to (and after) the wintering of up to 13% in the period of stay on the southern continent.

Similar results were obtained for parainfluenza viruses. The majority of subjects showed a decrease in cellular immunity, that is, their bodies are under constant exposure to cold become more vulnerable to pathogenic microorganisms.

The longer the exposure to cold temperatures, the lower the body’s resistance to dangerous infections for him. And we are not talking about weeks and months, as in Antarctica, but only on the day. Already after 48 hours of stay in the cold air the risk of infection of the upper respiratory tract increases.

Even the spread of viruses by aerosol (i.e., when coughing and sneezing) depends on the air temperature. In experiments with Guinea pigs it was shown that with increasing C +5°C to +20°C, the efficiency of transmission of viruses between animals decreased with each additional degree. The spread of infection by aerosol is completely stopped at +30°C.

Winter drought

In the winter we hide from the cold in warm houses. Hot battery — our all. But they dry the air — and it also increases the risk of Contracting respiratory viruses. The mucous membrane dries up and can no longer as effective as before, to protect the respiratory tract from viruses.
In addition, it is proved that the maximum survival rates of influenza virus observed at a lower relative humidity and reduced as it increases. In the same experiment with Guinea pigs, which we mentioned earlier, it was found that the highest prevalence of influenza viruses by aerosol was observed at 20-35% RH, and the lowest at 80%.

Caution: people!

The cold drives us home. We walk less and communicate more indoors. This means that it increases the risk of cross infections of diseases that are spread in clusters of people.

For example, it is estimated that, starting from +18°C, lowering the temperature leads to an increase in mortality. Moreover, the high-risk group were people who live in houses equipped with air conditioning, lack of exercise and wearing sufficient clothing.

Frost, sun and infection

In winter, the population receives much less ultraviolet light than in the warm season. First, people spend less time outside, and secondly, daylight is shorter, more cloudy days — the amount of ultraviolet radiation reaches the earth, reduced themselves. But without the UV rays, our bodies cannot provide themselves with vitamin D, which, in turn, are involved in the synthesis of cathelicidin LL-37. This so-called nonspecific immunity factor is a small protein with antibacterial activity that also protects the body from attacks all pathogens from the outside.


Our body does not like cold. Immunity in the cold season decreases and colds viruses and flu, by contrast, is gaining momentum. To no loss of health to survive the cold season, it is necessary to adhere to the following principles:

Should be aware of their vulnerability and not to give unnecessary cause for low immunity.
A good night’s sleep, a healthy diet, regular exercise, hardening, that is accustoming of an organism to changes in temperature — all these simple steps for a healthy lifestyle can reduce the risks of the disease with hypothermia.
The premises must be maintained a certain level of humidity. Dry air makes it easier to viruses and bacteria. If for any reason you can’t create a healthy atmosphere around yourself, you should use a moisturizing spray to the nasal mucosa.
The premises should be warm: warm comfortable, and viruses — no.
Avoid hypothermia during long walks or outings in the winter.

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