16 gennaio 2015

To believe is to be cured: the common cold, the rhinovirus and the placebo effect

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Waking up one morning, you have the impression that something went wrong: your nose feels as though you had snorted pastry flour, and your mouth (which was wide open all night long) is like dried mud. You got a cold.
 Soon enough, your nose sheds the layer of solidified mucus plastering it, and starts letting out gallons of snot, soaking whole boxes of tissues (as many as you have), then the wrist of your sweaters and shirts; until you'll be forced to suck the blob in and swallow it. 

"It must have been because yesterday evening I had no scarf on..." you'll think.
(You are Italian, and fear whiffs of air more than tornadoes, and autumn drizzles more than tsunamis. )
But you are a little unsure of the explanation, since you were wearing anyway your standard winter ice-pole-jacket, and with 15 °C outside you felt like in a sauna.
Anyway, even though seasonal cold peaks do exist (and might have something to do with the temperature), you don't catch a cold because of the cold: it's a virus which makes you sick.

Hundreds of different viruses can give you a cold. Rhinoviruses are by far the most common ones. These viruses are so efficient that even when just a few of them get into your nasal cavity, an infection can be triggered.
They usually get there because, after touching a contaminated person or object (a bus pole, a banknote, a supermarket cart) we pick our nose, or we stick a finger in our eye (which is connected to the nose).
(The mouth seems to be a less welcoming environment for the virus, therefore kissing (a person with a cold, a banknote or a bus pole) should not be too risky.)
nose picking for pleasure, cold virus book comic cartoon
This book really exists!!
Once they are inside our airways, rhinoviruses move to the throat and settle by the tonsils, where they start busying themselves with typical virus pastimes: entering cells, exploiting them to create copies of themselves, and then making them burst out in a bloody pulp, in order to release the new viral particles.
In spite of all this violence, rhinoviruses and their friends are little more than bad boys, enjoying the occasional disruption of a cell but not really doing any harm.

The best strategy for the immune system would be to control the infection for a few days, until it dies on its own with little damage and no major symptoms. However, in most cases our body overreacts and things get more complicated.
Inflammatory substances released by immune cells lead to blood vessel dilation and leakage. This causes nose swelling, impairs normal breathing and increases the production of mucus, which then overflows all over the place.
Nasal irritation triggers serial sneezes, representing our nose's clumsy attempts to get rid of the whole mess. Anyway, after a couple of days symptoms fade away, and within a week almost all cases are over.

Children are rhinoviruses' favourite victims: it might be because children explore more eagerly than adults their own nasal cavity, and without shame; or because they keep touching everyone and everything, and are therefore more exposed to viral contacts (especially at school).
Moreover, kids' immune system hasn't yet come in contact with all different kinds of viruses, so it lacks the protective antibodies adults had the chance to build-up during previous infections.

Children who are often sick may incur in a quite common complication: otitis. When the respiratory system is too congested, the mysterious passage connecting throat and ear - the eustachian tube, necessary for ear-to-throat fluid discharge - may become clogged.
When its sink is plugged, the ear fills up with a sludge, supposedly sterile, but most often contaminated with a few very tiny bacteria. These are perfectly at ease in the swampy environment, and thrive, causing earache, that is otitis.

This must be treated as appropriate: by ear candling, or pouring warm oil into the ear (classical and deadly granma's remedies); or simply using antibiotics. But antibiotics won't cure your cold, as they are only active against bacteria.
As a matter of fact, there are no remedies for a cold: first, because it's hard to find a drug so efficient that it makes even shorter an already very short illness; second, because there are so many viruses involved, that it would be quite hard to find something affecting them all.
As for the universally beloved vitamin C - deep in your heart you already know it - it is basically useless (except during very harsh physical stress).
Or rather: it won't help, if you don't believe in it.
But if you do, it might work.
This is because of one of the most amazing medical wonders of all times: the placebo effect.

A placebo is a pill which should contain a drug, but instead it has nothing inside (except sugar or other inactive substances). The placebo effect is an improvement of symptoms (or a cure) which follows the administration of placebo: it is therefore a purely psychological effect, triggered by the patient's conviction that he is taking an effective drug.
This effect is so widespread that whenever a new drug is tested, it has to be compared to a placebo, similarly looking but biologically inactive; and neither patients nor physicians should know until the end of the experiment which pill they were taking/prescribing.

placebo effect virus cold comic cartoon

In the 70's, the efficacy of vitamin C for the prevention and treatment of cold was tested on 200 volunteers. At first sight, vitamin C seemed to confer a (slight) advantage over placebo in the duration of symptoms.
However, when - at the end of the test - volunteers were asked whether they thought they knew (by the taste of it) what they had been taking, many answered yes, and some of them could indicate correctly whether they had been treated with placebo or vitamin C.
Those who guessed correctly they were taking vitamin C were healthier; whereas those who did not know, had no benefit from the vitamin.
But the weirdest thing was that those who believed they had taken vitamin C (but they had not) were healthier than those on the vitamin, who thought they were taking placebo. It was therefore a pure and splendid placebo effect.

Some studies have shown that introverted, continuously stressed or antisocial persons are more prone to get a cold. How this happens, we don't know. Whatever the reason, you know what to do to stay healthy: have a lot of friends, be open and relaxed, and above all... believe.

In what? In anything!
The important thing is to believe.

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Sources and Further Reading  
scientific articles  
Mechanisms of transmission of rhinovirus infections