Prawns left TV presenter Lee McKenzie unable to breathe: Have you got a killer allergy you don't know about
01:15 GMT, 22 May 2012
01:15 GMT, 22 May 2012
'I had no idea I had an allergy to shellfish,' said BBC Formula 1 presenter Lee McKenzie
As A BBC TV Formula 1 presenter, Lee McKenzie is used to high-octane action.
But she didn’t expect the drama of a severe allergic reaction that landed her in hospital.
The culprit was prawns she’d eaten at a restaurant in Monaco, where she was covering the Grand Prix.
They sent her into a life-threatening anaphylactic shock and left her struggling for breath — despite the fact she’d never had problems with food before.
Anaphylaxis is an extreme allergic reaction affecting the whole body, often within minutes of exposure to an allergen.
Around 750,000 Britons are thought to have suffered an anaphylactic reaction — commonly caused by nuts and bee and wasp stings.
But the numbers are rising dramatically: hospital admissions increased by 700 per cent between 1990 and 2004, according to government health watchdog the National Institute for Health and Clinical Excellence (NICE).
People diagnosed with an allergy know that they are at risk — but an anaphylactic reaction can also happen without warning.
Doctors say it’s crucial to look out for ‘clusters’ of seemingly minor symptoms that may hint at the possibility of a more severe allergic reaction. If you have the symptoms, you should get tested.
Lee, 34, says: ‘I had no idea I had an allergy to shellfish, it happened without warning.
'I’d never been a fan of shellfish, and the last time I ate it was probably when I was about 14, but I don’t remember any problems.’
When Lee was in Monaco in 2007, she decided to challenge her aversion — and ate king prawns twice in one day.
‘I had one on top of a meal at lunchtime and quite liked it, so that night I ordered them for a main course.
‘But as the evening went on, I started to get itchy arms and wrists. I’m quite an allergic person — I have hay fever and an allergy to horses — so I just ignored it, as I thought it was nothing to worry about.’
Within ten minutes, the picture had changed.
‘I was dizzy, unable to speak and couldn’t feel my face and lips,’ says Lee.
‘My mouth went numb, like I’d had an injection at the dentist. My friend Rebecca and I left the club we were in and I staggered around outside, fighting to catch my breath as my throat got more constricted.’
Anaphylaxis rise has been blamed on Western diet and changes in diet
Lee’s reaction was due to the sudden release of chemicals, including histamine, from cells and tissues.
These cause fluid to leak from the bloodstream into the tissues, leading to a drop in blood pressure and a lack of blood supply to the major organs.
Symptoms include laboured breathing, rashes, throat and mouth swelling and feeling faint. Lee’s friend flagged down a motorist who took them to a police station, where an ambulance was called.
Lee recalls: ‘We couldn’t say to the paramedics in either French or Italian that I had eaten shellfish.’
She and Rebecca then called former Brazilian F1 driver and friend Nelson Piquet Jr, who’d been out with them that night.
He spoke to the paramedics over the phone.
Lee recalls: ‘He told the ambulancemen everything they needed to know.
'He couldn’t remember the word for “prawn”, so described it as an “orange half-moon shape with a head and legs!” The medics got the message.’
By then, Lee was dropping in and out of consciousness. She was put on a drip and strong steroids, and kept in hospital overnight.
Two days later she returned to the UK, where tests confirmed her allergy to shellfish.
She says: ‘I had no idea you could have such a severe reaction for the first time as an adult.’
Dr Adam Fox, a paediatric allergist at Guy’s and St Thomas’s Hospitals, London — and spokesman for the British Society for Allergy and Clinical Immunology — says that, as with all allergies, you need to have been exposed to the offending allergen before an anaphylactic incident.
Your body then ‘recognises’ it and reacts to it when exposed to it again.
‘That first exposure may have been years ago,’ he adds, ‘and wouldn’t have caused any reaction at the time.’
Moira Austin, of the charity Anaphylaxis Campaign, says this first exposure doesn’t always involve ingesting the allergen.
‘There is a theory you can be exposed through the skin, such as children being exposed to peanut proteins via arachis oil in skin creams, or even through touching door handles with an offending allergen on them.’
'This is more likely when the skin is broken, such as with eczema.
No one is entirely sure why anaphylaxis is on the rise, although it has been blamed on Western diet and changes in diet, such as exposure to new foods like kiwi fruit.
So should we all be anxious that we might suddenly develop a severe food reaction
Dr Fox says: ‘You are only at real risk if you have that tendency already — i.e. you already have other allergies like pet allergies, asthma or eczema.’
And Dr Adrian Morris, allergy consultant at the Surrey Allergy Clinic, says sufferers have probably always had the food allergy but not known it.
‘Some people have allergies as children then avoid that food for years, like a subconscious self-preservation,’ he says.
‘When they reach adulthood, peer pressure forces them to eat it again, and they could experience an anaphylactic reaction.’
Once you’ve had a food allergy, the level of your reaction will usually stay the same — it is unusual for a previously mild reaction to trigger an anaphylactic shock.
‘If you’ve eaten a food that makes you wheezy or your mouth or lips tingle, 90 per cent of the time you will react in exactly the same way on each exposure,’ says Dr Morris.
‘It’s a bit of a myth that with each reaction you’ll get progressively worse symptoms.’
An estimated 21 million adults in Britain have at least one allergy, and the number increases by five per cent a year. So is there a definitive way of knowing if you’ll have anaphylaxis in the future
The standard procedure to identify the allergen is a blood test — but only after an anaphylactic reaction. However, there is a newer test, component resolved diagnosis (CRD), to help predict risk.
It pinpoints at molecular level the exact proteins responsible for the allergic reaction.
For example, it reveals if you are allergic to the protein that causes the severest peanut allergy or the proteins that cause only mild reactions.
Dr Morris, who uses this newer test, says: ‘CRD is very useful for predicting anaphylaxis risk, particularly for identifying peanut, hazelnut, fruit, cows’ milk, egg and wasp-venom allergies.
‘It’s available on the NHS and is likely to become more used as doctors find out about it and become familiar with when to use it.’
It’s also important to look for warning signs. Dr Matthew Buckland, a clinical immunologist at the Royal London and the BMI London Independent hospitals, says: ‘There are a few reactions that set alarm bells ringing.
‘These are hives on the skin, and feeling faint and light-headed, which could be a sign of dropping blood pressure.
'Some people might also get localised swelling, such as on their lips. If someone has this cluster of symptoms, they should get it investigated.’
They should ask their GP to refer them to an allergy clinic.
Lee now carries two adrenaline pens with her all the time, so she can inject herself in the event of another reaction.
She also has translation cards telling people of her allergy in the language of whatever country she is visiting.
She is determined not to let her severe allergy disrupt her life, though.
She says: ‘This weekend I’m in Monaco for the Grand Prix again — but I’ll avoid the prawns!’
Anaphylaxis Campaign has launched an AllergyWise online training guide so people can learn more about severe allergies. See anaphylaxis.org.uk