Evil under the scum

Gardening may seem like a harmless pastime, but watch out. You might be digging your own grave.

Imagine a picturesque garden scene: what could be more comforting? An elderly lady is carefully pruning back the roses around the front door of her Somerset cottage, a wooden trug in the crook of her elbow. She hums gently to herself in the late summer afternoon heat, and curses mildly as she pricks her thumb on a thorn.

The image could come straight from The Darling Buds of May or John Major's vision of an England of warm beer and bicycling spinsters. Except that the outcome is more Norman Bates than HE Bates. A few days later this harmless elderly lady is dead, killed by one of the deadliest poisons known to man, and by her apparently innocuous hobby - gardening.

This story, which is posted on the wall as a cautionary reminder to casualty officers in one West Country hospital, alerts us that when we venture out into our gardens, we are not simply enjoying the safety and serenity of our backyards. We are entering another world of lethal, malevolent creatures every bit as nasty as the denizens of the Amazon jungle or the Pacific depths. It's just that we can't see them.

The beast that killed the lady in our story was so tiny that tens of thousands of them could fit upon this full stop. The poison they produce - tetanus toxin - is more deadly than anything in Saddam Hussein's biological arsenal.

Tetanus toxin blocks the transmission of impulses through every nerve in your body, causing rapidly progressive paralysis, including the notorious lockjaw. It the disease is untreated, the poison makes your body fix into a rigid, arch-like spasm and your lips stretch into a hideous sardonic grin, before the nerves that keep you breathing are switched off, and you die.

According to style gurus, gardening is supposed to be the new sex, and just as with sex, you need to take precautions. Most of us will have had tetanus shots as children and regular boosters ever since, although misplaced scares about immunisation have meant that the uptake is falling. Up to 25,000 people in the world are believed to die of tetanus each year. Our poor old lady had let her boosters lapse, and her age meant that her immunity was waning. But what other diseases lurk among your nasturtiums, apart from the obvious hazards such as wasps and stinging nettles?

Tetanus belongs to a vicious family of bacteria, called the Clostridia. It includes Clostridium welchii which causes gas gangrene - foul-smelling, flesh-eating scourge of the trenches - and C botulinum, which causes botulism. Both live in the soil. Contaminated garden injuries can sometimes lead to gangrene. The poison that botulinum produces is more potent than Sarin. One teaspoonful is said to be enough to kill five tons of guinea-pigs. Botulism is usually spread by faulty preservation of foodstuffs, including garden produce.

"If you live in a modern city your garden is a dilute solution of cat stools," says Graham Rook, professor of medical microbiology at University College, London. Cats, dogs and wild animals all carry parasites that can be transmitted through your garden soil. Parasites such as Toxocara felis and T canis. These are spread in the faeces of cats and dogs; they can cause blindness as well as heart and lung damage, particularly in small children.

Toxoplasmosis is also shed by cats in their litter. It is particularly dangerous to pregnant women - it can cause birth defects and abortions, as well as meningitis in people who are already unwell. Tapeworms can also be picked up by inquisitive children as they explore contaminated soil.

Garden moulds can cause nasty illnesses, particularly if your immunity has been damaged by old age or diseases such as HIV and cancer. Aspergillus is a fungus that grows on decaying plants. It can cause dangerous lung infections, leading to a tendency to bleed copiously, as well as infections elsewhere in the body. It is also a common cause of asthma, with some reports saying that up to one in 20 asthmatics may owe their wheezing to having been exposed to this tiny, mildewy germ.

If your garden boasts a pond, you are asking for even more trouble. Fish- fancier's finger is a cause of skin ulcers, thanks to a cousin of TB called Mycobacterium marinum, which lives in ponds and fish tanks. And if you happen to fall into a garden pond, do try to keep your head out of the water - there is a nasty bug called Naegleria fowleri which would just love to swim in through your ears or throat and cause fatal meningitis.

Before you call in the JCBs to concrete over your herbaceous borders, bear in mind, however, that there is a more positive side to the lethal jungle that is your garden. Some doctors are beginning to believe that exposure to some soil bugs can even be good for you. Recent reports have shown that the children of farmers are less likely to develop asthma and allergies, despite their added risk of diseases spread by farm animals, such as leptospirosis, Q fever and anthrax.

So is your garden a potential death trap, or a medicine cabinet? The answer is probably both.

Dr Robert Baker is research Fellow in infectious diseases at the Centre for Infectious Diseases in central London

How to Protect Yourself in the Garden

WORRIED ABOUT the dangers of gardening? Here's how to stop a hobby turning into disaster.

Make sure your tetanus shots are up to date. You should have a booster every 10 years, more often if you get a dirty injury.

Wash your hands after gardening and before eating.

Wear gardening gloves, especially if you are pregnant. Your doctor may be able to check your natural immunity to toxoplasma if you are worried.

Clean away cat and dog faeces immediately, using gloves, then wash your hands. If pregnant, get someone else to do it.

Wash any injuries thoroughly and remove all visible dirt.

If your injury becomes red and inflamed, seek medical advice as soon as possible.

Always wear rubber gloves when cleaning your pond; if you fall in, shower immediately and ensure you wash out your ears.

If your immunity is damaged for any reason, avoid gardening in the autumn when moulds are at their most productive.

Don't let your small children eat soil - get a sand-pit, and keep it covered over when it is not being used.

Wash or peel garden produce before eating; boil thoroughly before preserving.