Cold, hands, soap, hat… we sort out preconceived notions about winter infections

For all those for whom winter rhymes with practices passed down from generation to generation: we’ve picked out some viral myths, and tried to separate fact from fiction with the help of Clermont-Ferrand University Hospital’s Department of Hospital Hygiene.

Don’t go out with wet hair. Do not walk on tiles with bare feet. ” Got a cold ! » Even when hearing the announcement of nausea, we find ourselves repeating the cliché like a mantra. What if it was nonsense? To sort things out, we turned, among other sources, to the Hospital Hygiene Department of the University Hospital. Ousmane Traoré , head of the department, puts some order to preconceived notions.

1. “Catch a cold”?

A cold alone does not make you sick unless you have been exposed to a pathogen (virus, bacteria, parasite, mold, or chemical agent). Unless you actually have a part of your body frozen. On the other hand, exposure to cold can cause irritation (trachea, skin, etc.).

Muscle contractions in the cold can also cause pain or awareness (contractions, stiffness, etc.). The idea of ​​catching a cold refers to a weakened immune system and the failure of more delicate mucous membranes in winter. “For this reason, contact with the virus can lead to infection more easily,” believes Professor Traure.

Ultraviolet radiation is less likely to degrade microorganisms.

American work, published in 2022, also concludes that there is a relationship between susceptibility to winter viruses and a decrease in the temperature of the nasal walls: at 32 ° C instead of 36 or 37 ° C, they will fulfill their barrier role less well. natural

2. Are there more epidemics in winter?

“That’s the big question we’ve been asking ourselves for decades. There are hypotheses; no real certainty.”

First hypothesis: prolonged survival of pathogens in winter environments. “They are less exposed to radiation. We especially know the antibacterial effect of UV.”

Winter is associated with a more limited lifestyle, with more contact between humans, obscurity in transportation, at work, etc.

Second hypothesis: Exciting social factor. A mix of population is also seen during winter holidays. The result is that more virus is excreted through the breath. Which will survive in higher density in a given place. “Our parents were acting common sense by ventilating regularly?!”

3. Aeration or ventilation?

Ventilation is never a bad idea. But mechanical ventilation can be. Breathing in contaminated air helps spread the virus present. “But contaminated ventilation systems have only been shown very exceptionally, particularly for the culpable restaurants in China.” However, this remains possible (especially in airplanes where the environment is exceptionally closed).

A 21st century challenge may be linked to the conflicting mandates between thermal insulation and air circulation.

What is proven is that a poorly maintained ventilation/air conditioning system can cause problems on its own. It can harbor mold, bacteria etc. “It needs to be maintained. It’s not a matter of installing it and letting it live!”

Finally, insufficient aeration or ventilation can also promote moisture in the walls: it will be favorable for the proliferation of mold.

4. Does the virus survive for a few hours? Or a few weeks?

“The most resistant pathogens are gastroenteritis viruses” (norovirus, rotavirus). There are many. They usually cause vomiting and diarrhea. They can survive in the environment for several weeks. “They are also the most resistant to: heat, ultraviolet and pesticides.”

Ultraviolet radiation is less likely to degrade microorganisms.

But watch out for bacteria, especially Echariskia coli or Staphylococcus aureus. They can survive on inert surfaces for several months.

5. Through the nose? the mouth? eyes? hand?

Viruses are spread mainly through human contact, with and without touch. Respiratory viruses are transmitted in terms of relative proximity between individuals. But other factors come into play: humidity conditions, projection (quiet breathing or rather coughing, sneezing, singing). As for defensive spacing: “It’s a big factor in the debate, reinforced by Covid…”

The rule is that it is better to stay 2 meters away from an infectious person than 1 meter.

In addition to the direct respiratory mode, hands can be contaminated: during parasitic gestures. “You first contaminate your hands, then, depending on what you’re going to do, you contaminate yourself by touching your eyes, your nose… But the disease is caught through the eyes or the respiratory system: not through the hands! “

For most viruses, the digestive tract is not a source of contamination. That’s part of it for bacteria.

6. Going to the toilet: serious?

“The most important human microbiota is found in the digestive system. In 1 gram of stool passed by a person suffering from gastroenteritis, there is an extraordinary amount of viruses. It only takes one very small mistake. There are thousands of viruses on a door. A handle, a toilet flush… ” However, it only takes a few dozen microorganisms to develop gastroenteritis!” “It’s a high-risk area where hand hygiene is essential.”

7. Soap or hydroalcoholic solution?

“Hydroalcoholic products are more effective than plain soap. But of course, you must use soap and water for visibly dirty hands!” Be careful, not all hydroalcoholic solutions are the same. “You need at least 70 or 75% alcohol.”

Bleach remains the best disinfectant for objects and surfaces. But used in proper dosage and before expiry date. “Bleach degrades very quickly and heat accelerates degradation.”

Laurent Vauquiz announced several measures for health in Auvergne in 2024

Annie Borges

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