Jellyfish were floating in the tropical seas and in the cold waters of the Arctic 650 million years ago, long before dinosaurs ranged around London and even longer before mammoths walked along Cromer beach.

Usually this country’s jellyfish are happiest living 20 to 40 miles from the coast. Although they can propel themselves to some extent with their umbrella tentacles, they are mainly dependent on the currents. The waters well off shore suit them best as they are warmer than those near the coast, which are chilled by water from the rivers, and are also less salty.

But when there is a drought, the flow of land water is less abundant and the coastal water becomes more saline, warmer and more conducive to jellyfish. Hence the outbreak of minor skin problems suffered by bathers and children on the beach.

Just as wasps and bees upset landlocked family picnics, so can jellyfish disrupt a day on the beach. On the continent, where jellyfish are near the beach for the greater part of the year, recommendations are issued by the Mediterranean Centre for Marine and Environmental Research. Unless there is a hot summer, we don’t have to worry too much about jellyfish stings, but in a year such as this we should take advice from our European neighbours.

This week it was announced that, around the Mediterranean basin, at least 30,000 people have already been stung this summer. Some Spanish beaches have been closed, with up to ten jellyfish per square metre recorded in adjacent waters. And beach guards are quick to warn that the tentacles of jellyfish can break off and the resultant floating fragments remain capable of stinging.

I recall in my childhood that holidays were enlivened by a dead jellyfish or two on the beach. We hadn’t heard of the French experts’ opinion of the dangers of walking barefoot along the water’s edge where dead and fragmented jellyfish could be hazardous. In fact, children and others may be stung until the stranded jellyfish has been baked in the sun for 24 hours.

Most parents adopt quite the wrong way of dealing with jellyfish stings. I remember being rubbed down with towels and washed in cold water. Cold, fresh water causes the jellyfish cells to burst, releasing the poison within them. If the picnic is a good one, there presumably will be a ready supply of ice: this should be held in a plastic bag against the stung area. My mother’s brisk rubbing with a sandy towel, while dowsing everywhere in cold, fresh water , must have shattered every jellyfish cell in the affected area.

Wherever possible, tentacles should be removed — but by the careful use of pincers rather than fingers, and preferably by someone who is equipped with latex gloves.

Very occasionally, just as with the sting of a bee, a highly sensitive person who shows an allergic reaction to the venom may have even worse trouble if stung on subsequent occasions. Fortunately, any serious difficulty on a British beach is rare. The worst that someone stung by a jellyfish is likely to suffer is an unpleasantly itchy skin that responds to antihistamine by mouth and a steroid cream.

It is very different in Australia, where the notorious box jellyfish can produce a violent and dangerous reaction. The first-aid treatment for this is to deluge the affected area with vinegar, followed by a baking-powder compress. If there is no vinegar, available, then Coca-Cola does almost as well.

A CATFORD READER has e-mailed us a question about probiotics. Having read recent reports on their use, he wonders if it is only the over-sixties who should be taking them.

The potential value of probiotics has been understood for nearly 100 years. The problem has been to link an obviously sound theory to any evidence of practical advantage. The recent publicity is welcome as it draws attention to the features of probiotics that give them a chance of improving the health of those who take them — regardless of age.

The over-sixties have a greater likelihood of having a relatively poor immune system, but carefully chosen probiotics could be useful in younger people as well.

I feel that probiotics are best taken in tablet form. The difficulty lies in implanting friendly bacteria at a point in the lower gastrointestinal tract where their short life will have a chance of helping the person. If the probiotics are not to be the source of false hopes, the good bacteria in the preparation must reach the gut in adequate numbers, having survived the acid from the stomach and gallbladder, as well as other digestive enzymes.

The coatings on the tablets must overcome this battering from the acids in the upper gastrointestinal tract but nevertheless dissolve in the lower gut, with the bacteria within them unharmed.

Equally, the coating mustn’t be so impervious that the tablets pass straight through the gastrointestinal tract unaltered, only to be flushed down the sewers.

The second essential requirement is that the good bacteria must survive and flourish in the guts for at least 24 hours if they are going to influence its flora. The effective probiotics on the market meet these two basic requirements.

To ensure their efficacy, probiotics must be taken at least once a day. An occasional probiotic, even the repeated but occasionally missed tablet, also destroys their usefulness. Any probiotic chosen should have undergone the same standard rigorous trials as other drugs: the trials should be randomised, double-blind and placebo-controlled.

The gastro-protective coating on the tablets should also give them a reasonable shelf life without refrigeration.

ASK DR STUTTAFORD

ONLINE: E-mail your queries about Parkinson’s disease to Dr Stuttaford here.

NEWSPAPER: Send your questions on any medical topic to drstuttaford@thetimes.co.uk or to times2, The Times, 1 Pennington Street, London E98 1TT. Please include the following: the symptoms (and how long they have been present), the person’s age, sex and marital status. Dr Stuttaford’s replies cannot apply to individual cases but should be taken in a general context. Readers are always advised to consult their GP, as only he/she will be fully conversant with the background. We regret that Dr Stuttaford cannot enter into personal correspondence.

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