Saliva does not transmit cold virus
By Lucy Atkins
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Blood vessels constrict when the skin is exposed to a cold stimulus. This restricts the activity and ability of white blood cells to fight off a cold virus.
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IF YOU are among those to have called in sick from work this week with a cold (you probably called it flu — it sounds so much more convincing that way, does it not?), you may have tried a range of remedies, bought or home made. Chances are none of them will have cured you.
You may be kicking yourself for not wrapping up warmly enough. Or, more likely still, you are kicking someone you know for infecting you. There, too, you could be mistaken. We all think we understand the common cold. Yet few of us have a clue about how we get it or what to do to shake it off.
French kissing harmless
Take kissing. You would have thought that French kissing a snotty lover was a bad idea on many levels. But contrary to widespread belief, it is very hard to catch a cold by exchanging saliva. In 1984, researchers had the unenviable job of observing hundreds of students kissing. Kissing, they concluded, resulted in no transmission of the cold virus.
"The virus travels in the mucus from the respiratory system," explains Professor RonEccles, director of the Common Cold Centre at Cardiff University, Wales. "Unless you have a bad cough, and some of the respiratory mucus has made its way into your saliva, the cold virus will not be transmitted by kissing."
Most of us think colds are highly contagious. Certainly, most adults get two to five colds a year (schoolchildren can catch double this number). But scientists say colds are not, in fact, terribly easy to pass on.
This is because the mucus from the respiratory tract of someone infected has to get directly into your respiratory tract.
To do this, an infected person must either sneeze or cough near you so you inhale their infected droplets, or touch a surface, allowing you pick the virus up on your fingers.
Depositing the virus
You then rub your eyes or touch your nose (your eye drains into your nose), depositing the virus in your own respiratory tract.
Since you touch surfaces handled by thousands of individuals every day and breathe in the droplets of a variety of sneezing strangers, it would be harsh to blame your loved ones for every sniffle you develop.Indeed, for every symptomatic individual, there are two or three infectious people touching things with virus-infected fingers.
Hand-washing may reduce infection rates, but, as Eccles admits, "You'd have to wear a space mask to rule it out entirely."
Since so much is known about cold viruses, it seems amazing that no pharmaceutical company has come up with the cure that would make its fortune. There are a couple of flu `antiviral' injections in use which, if administered within the first 24 to 48 hours of illness, are said to shorten some flu bouts by a day or so. But these will not touch a cold.
Cold viruses, while they manifest many `flu-like symptoms' (fever, runny nose, cough), are different from flu viruses. Cold symptoms come from 200 different viruses (though up to half of all colds are the fault of one culprit, the `rhinovirus').
To kill a cold you would have to kill the specific cold virus that has seized you. One American company did recently invent a vaccination against the rhinovirus but, says Eccles, "It had to be taken off the market because women taking it kept getting pregnant." So do we just have to accept colds as inevitable? In recent years the myth that you catch a cold by getting chilly seemed to have been debunked.
But now there is a backlash that grannies everywhere will welcome: "If you expose the skin to a cold stimulus, this constricts your blood vessels," says Eccles.
"Since your immune system resides in your blood, this constriction can restrict the activity of your white blood cells" — thereby inhibiting your ability to fight off a cold virus.
Indeed, he says, it may be that we get more colds in winter not just because we are crowded into overheated spaces, but because our noses are cold. Coughing can last 10 weeks. Similarly, other foods such as garlic — another clinical `grey area' — peppers and onions have `antiviral properties' that may help fight the virus.
Not waste of money
Over-the-counter cold treatments might not be a waste of money either. Drink hot honey and lemon and take paracetamol for your headache.
Nasal congestion, caused by swelling of the large veins in the lining of the nose, often stops you sleeping, so decongestant sprays and other night time remedies can help you fight a cold, says Eccles, because they promote sleep, which restores your busy immune system. — ©Guardian Newspapers Limited 2005
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