By
Pat Hagan

PUBLISHED:

17:38 EST, 13 May 2013

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UPDATED:

19:09 EST, 13 May 2013

When a wasp stung Penny Rutland above her left knee as she sat in the sunshine on holiday in Dorset, she assumed all would be well once the initial pain passed.

She had been stung on her arm two weeks earlier, and, apart from brief discomfort and skin irritation, was otherwise unharmed. But this time was different.

After five minutes, her hands began to itch. After about ten minutes, her left leg had become bright red and inflamed from the knee to the ankle, and five minutes later her tongue had swollen so much she could barely speak, her eyes were puffy and her hands had ballooned.

The experience of being stung can be frightening and leave people scared of enjoying the outdoors

Penny, 62, from Hemel Hempstead in Hertfordshire, had anaphylactic shock, the extreme, potentially fatal allergic reaction which can be triggered by reactions to everything from insect stings, latex and prescription medicines to foods including peanuts, kiwi fruit and eggs.

The fact it happened within a fortnight of a similar sting is not surprising, as it’s thought the more someone is exposed to insect venom, the more they are likely to react. Beekeepers have some of the highest rates of venom allergy.

Most people stung by insects will develop a local reaction at the site of the sting, causing pain, redness, swelling and itching. But a significant number — about 10 to 15 per cent — experience larger areas of swelling, which can last up to a week.

About one in every 150 insect stings in children and one in 300 in adults results in an even more severe and potentially life-threatening reaction. Between four and eight people a year in the UK die after reacting to a sting, with bee and wasp allergies the most common.

Even for those whose allergic reactions are less extreme, the experience can be frightening and leave them scared of enjoying the outdoors.

But Penny is one of a growing number of patients with allergies to insect stings being cured by a treatment that involves injecting tiny amounts of the poison that causes the problem in the first place.

Venom immunotherapy works by introducing minute quantities of an insect’s sting into the body and gradually increasing the dose so the immune system becomes used to it and doesn’t overreact.

The massive overreaction by the body’s own defences, rather than the venom’s toxicity, causes the anaphylactic shock.

Cells in the immune system release massive quantities of histamine as they detect the allergen. This chemical makes tiny blood vessels more permeable so immune cells can penetrate affected tissues and fight invaders.

Beekeepers have some of the highest rates of venom allergy

Normally, the release is carefully controlled and histamine is directed only to the area where the damage has occurred.

But
if someone has a severe allergy, it can trick the immune system into
flooding the whole body with dangerously high amounts of histamine,
making blood vessels dilate and leak fluid into surrounding tissues,
causing the rapid swelling seen in severe reactions.

As fluid drains out of the circulatory system, there can be a sudden, dangerous drop in blood pressure, which can cause major organs to pack up.

Current treatment relies on injecting the hormone adrenaline immediately — this reduces swelling, eases inflammation in the lungs, increases blood pressure and stops immune cells pumping out vast quantities of histamine.
Venom immunotherapy is not a new treatment. It was popular in the Fifties and Sixties, but neither doctors nor patients fully appreciated how narrow the margin was between it being safe and potentially fatal.

In 1986, a paper in the British Medical Journal reported that 26 people in the UK had died from allergic reactions to venom immunotherapy over as many years. Consequently, interest in the treatment faded.

But a review last year of seven trials, involving almost 400 patients, concluded that venom jabs are highly effective. Now the National Institute for Health and Care Excellence (NICE) has issued guidance recommending the treatment be extended to more patients (currently it is given only in specialist clinics).

It calls for immunotherapy to be made available to those who experienced a ‘moderate’ reaction but are anxious about it happening again, as well as patients who suffer severe reactions.

‘It makes a huge difference to patients’ quality of life once you factor in the anxiety they suffer around the possibility of being stung again,’ says Dr Robert Boyle, a consultant paediatric allergist at St Mary’s Hospital in London, part of Imperial College Healthcare NHS Trust, who was involved in compiling the review.

‘Stings rarely kill, but they can be very frightening. Once people have the treatment it gives them confidence to take up outdoor activities again. But many GPs are unaware of the treatment.’

Penny and her husband Peter, 65, a retired marketing manager, had taken his mother, 91, on a caravan holiday in September, 2011 when Penny was stung.

‘It was terrifying,’ says the retired secretary and mother of two. ‘I was sitting outside when I saw a wasp land on my leg. Before I could brush it off, it stung me. Within a few minutes my hands and feet were so itchy I poured a bottle of water over them to try to ease it.

‘When I looked in the mirror I was horrified. My eyes were puffy and swollen and my tongue looked like a burger. My hands were swelling so quickly I tore my rings off in case they got stuck.

‘I pleaded with a woman working in a neighbouring cafe to call an ambulance.’ Paramedics gave Penny an adrenaline injection and rushed her to Dorchester Hospital, where she was given oxygen and kept in for the rest of the day, until the worst of the swelling receded.

Her GP later referred her to the specialist allergy clinic at St Mary’s, where she received pioneering ‘rush’ immunotherapy.

In conventional treatment, patients have weekly venom jabs, starting with minute amounts and building up over six to eight weeks. They then have ‘maintenance’ doses every month for three years, and the treatment has a 95 per cent success rate.

During the ‘rush’ technique, the build-up is over six hours. The patients take steroids in the days before to reduce any inflammatory reaction. They are then injected six times in the day with rising amounts of venom.

It can shave months off treatment and saves patients travelling to the specialist clinic.

Long-term follow-up studies show this type of treatment still works after ten to 15 years. Initial research suggests the ‘rush’ technique could work for other allergies, such as pollen and dust mites, but it remains controversial due to the risk of severe reaction.

Why adults exposed to stings early in life with no major reaction later experience potentially fatal consequences remains a mystery. One theory is hormonal fluctuations later in life, especially in women, may be a factor.
Penny, who has not yet finished the full course of her treatment, hasn’t been stung since but carries an EpiPen — which contains adrenaline — in case she is.

‘This treatment is very effective,’ says Dr Boyle. ‘Beekeepers may need to have it repeated after ten years, but for most people it offers a lifetime cure.’