Jeremy Laurance: Watch out – you may come to regret that festive kiss

Warning of the week: beware of a Dyson under the mistletoe this Christmas. Not the vacuum cleaner, but anyone trying to impersonate one. It may start with a swoon but end with a searing pain and leave you deafened round the dinner table.

If you have never heard of the term before (in this context) it comes from a remark by a top ENT surgeon on the dangers of kissing. Discussing the case of the Chinese woman who reportedly lost her hearing in one ear after being "aggressively kissed" by her boyfriend, as reported in 'China Daily', Andrew McCombe, consultant at Frimley Park Hospital, remarked that the unfortunate victim must have had an infection or previous damage to her ear. "If you had normal eardrums, you would have to be kissing like a Dyson," he added.

It is an arresting image – two people, mouths locked, each trying to suck up the contents – but about as erotic as a street cleaner wrestling with a recalcitrant drain cover.

The damage was allegedly caused by the woman's boyfriend sucking so vigorously that he reduced the pressure in her mouth, which is linked to the ear via the Eustachian tube, pulling on her ear drum and causing it to burst.

The remarkable case raises a question about the other dangers of kissing. Germs of course, including those that cause colds, cold sores, glandular fever (the "kissing disease") and even tooth decay. Neck cricks, make-up malfunctions, dog breath and burns (be sure to remove the cigarette first).

But there is worse. A 14-year-old girl from New York contracted meningitis and was hospitalised, apparently after being kissed. The virus is spread in saliva and requires a substantial dose (as delivered in a kiss) for the disease to spread.

In Egypt, which has seen more than a dozen deaths from bird flu, doctors have warned against social kissing to reduce the risk. Paediatrician Adel Ashour of the National Centre for Research said: "I count 15 diseases that can be spread by kissing, including seasonal flu, German measles, chicken pox and tuberculosis."

There are other, less predictable dangers – such as the warning to avoid a clinch while leaning against a car. It may drive away. Better stick to hugs, while securely anchored on two feet.

***

So, why do some people get fat while others, who seem to eat the same and take the same amount of exercise, stay slim? Common sense suggests the answer must lie in the genes. Yet how then can we explain the growth of obesity over recent decades? Genetic change – evolution – doesn't happen that fast, so common sense suggests the explanation must lie in our obesogenic environment – fast food joints, cars to transport us and TVs to watch. Despite this, when I look at people I know, I still find myself asking the first question – and wondering at the glorious variety of human kind.