Posts Tagged ‘venom’

Bees, wasps and other stinging insects

`Know your enemy’ is always a good motto, but particularly for those with insect-sting allergy. Being allergic to wasps or hornets, for example, is enough of a problem without panicking every time you encounter a hoverfly as well. If your reaction to this is ‘What’s a hoverfly?’ then you need a good field guide or a friend who knows a little about natural history. These common insects have yellow-and-black stripes to mimic those of wasps, giving them some protection against predatory birds. They fool a lot of people as well as birds, but it isn’t difficult to tell the two apart — hoverflies are a different shape from wasps, hold their wings differently at rest, and fly in a completely different way (for one thing they hover, unlike wasps). Being able to tell one from the other will make life much more relaxing.
If you did not see the insect that stung you, ask the doctor which skin tests came up positive (see p. 61), and use a field guide to check exactly what the insect(s) looks like.
As well as knowing what your problem insect looks like, you need to know a little about its habits and tastes.
These are the general characteristics of stinging insects that you need to know about:
• The most dangerous thing you can do is to disturb the nest – all stinging insects go into attack mode when this happens. If there is a nest in or around your house, call in a pest control expert to destroy it. Never tackle this job yourself, nor allow anyone else to do it while you are in the vicinity.
• If you think there may be an insect nest in or around your house, call in a pest control expert to do a survey. Regular annual checkups of your property are advisable if insects have nested before.
• Insect repellent works only for biting insects, such as mosquitoes. It does not repel wasps, bees or other stinging insects.
• Insecticide spray can be useful, but make sure the insect is really dead before you touch it. A groggy poisoned insect may well sting.
• A small but thick blanket can be useful for catching bees or wasps that have flown into cars. Don’t try to do this yourself unless there is no alternative. Ask a passer-by to help you if you are alone.
• Always stay as calm as possible.
Wasps and hornets (vespids)
• If you react to one species of vespid, you may well have a cross-reaction to other species in this group, so take care.
• Wasps like sweet foods (e.g. jam, honey, cakes) and you should avoid taking these on picnics. They will also crawl into open cans of beer or soft drinks. Never ever drink from the can, as you can get a mouthful of cross wasp with your drink.
• In spring and early summer, wasps collect protein-rich food for their young, and may be attracted to meat. If eating outdoors, as far as possible keep food covered.
• Wasps come to fallen fruit in the autumn. They get very sluggish and bad-tempered late in the year, and will sting with little provocation. They may crawl into crevices or hollow logs as winter approaches. Be very careful about picking up fruit or dead leaves, or working in the garden –always wear thick gloves.
• Wasps are often on the ground, especially in late summer and autumn. Wear shoes and socks for protection. If working outside where there may be wasps, long trousers and long-sleeved shirts are also advisable.
• Rubbish bins and litter bins are also very attractive to wasps. Make sure your own bin has a tightly fitting lid, and that no rubbish accumulates around it. Ask neighbours to do the same. Keep away from litter bins, and from picnic sites, orchards and tea gardens, all of which are havens for wasps.
Cross-reactions between insect stings
There are cross-reactions between the venoms of wasps, hornets and related insects (vespids), so if you are allergic to one, you may react to another. Cross-reactions are very unlikely between bee and wasp venoms.
Honeybees and bumblebees have very similar venom and these cross-react (but honeybee immunotherapy does not work for bumblebee allergy – see p. 168). Surprisingly, there is some cross-reaction between honeybee venom and snake venom.
The usual suspects
Wasps (yellow-jackets in the United States), hornets and bees are the most common source of allergic reactions worldwide. Locally, there are allergic reactions to various other stinging or biting animals. Fire ants are a particular problem in the southeastern United States. Hopper ants are a cause of anaphylaxis in Australia, and allergy to leech bites has been reported from Tasmania. A few people are allergic to the kissing bugs (Triatoma spp.) – also called cone-noses, ‘big bed bugs’ or ‘Mexican bed bugs’ – that are found in South and Central America, as well as rural areas of North America. These large insects creep into beds and bite painlessly, by night. In urban areas of Italy, where large numbers of pigeons live in some old buildings, pigeon ticks that find their way indoors have sometimes caused anaphylactic shock by biting during the night. Localised reactions to earlier bites had occurred in all cases.
Honeybees and bumblebees
• When it stings, a bee loses part of itself – the stinger and venom sac – and therefore dies. So stinging is very much a last resort. Most honeybees are not aggressive, and only sting if their nest is attacked, or if they are threatened when feeding.
• Bees feed on nectar from flowers. They may be attracted by brightly coloured clothes, especially red, orange and yellow, and flower-prints, mistaking these for flowers. Wearing dull colours is advised.
• Some perfumes, shampoos and scented cosmetics or lotions may also attract bees. If bees do approach you, never swat at them, and don’t panic. The best thing is to brush them away very gently.
• Bees often feed on clover, which grows in lawns and other grassy places, and it is easy to tread on them in this situation. Walking barefoot outside is therefore dangerous.
• Bees are attracted by water, including swimming pools and paddling pools.
• Although large, bumblebees are also very placid and rarely sting.
• Swarming bees are dangerous because they have the queen with them. If you see a swarm, keep well away.
Africanised honeybees
If travelling abroad, you should remember that Africanised honeybees – found in South and Central America, Texas, Arizona and parts of California – will sting with much less provocation than ordinary bees.
They are hybrids between domestic honeybees and an aggressive variety of wild African bee mistakenly introduced to South America. While they are much more pugnacious than ordinary bees, Africanised honeybees are only intent on defending their hive, and do not maliciously hunt people down as some horror movies have implied! They inject slightly less venom with each sting than a normal bee, but multiple stings are more likely because more than one bee is usually involved.

Let’s hope it never happens - but if it does, knowing what to do could make the difference between surviving and not surviving. The sensible thing is to read these pages - or whichever parts are relevant to you or your child - before you encounter an emergency. It is often helpful to rehearse the procedure in your mind and actually imagine yourself going through the actions described here.
Find out in advance what the local ambulance service is like, and ask your GP for advice about who to contact in an emergency. (If you have latex allergy, check in advance that all local ambulances carry a latex-free kit.) These are the options:
• Call your GP.If the doctor is nearby and the hospital or ambulance station a long way off, this may be the best decision. Doctors in rural areas may have supplies of adrenaline for emergency treatment, and oxygen for those suffering a severe asthma attack.
• Call an ambulance. Where the local ambulance service is dependable, this is always the best option. The ambulance crew will have adrenaline and oxygen.
• Go by car or taxi to the nearest hospital
emergency department. This is not usually a
good plan, because your condition may quick-
ly get worse, and you have no emergency
treatment available. But there may be situa-
tions where it is a sensible decision. Emergencies can occur when you are away on holiday or business. Never stay anywhere without a phone – check that it is working as soon as you arrive. Make sure you have the number of a local doctor and know where the nearest hospital is. A remote holiday cottage can be a dangerous place to suffer an asthma attack or anaphylactic shock.
Anaphylactic shock
This is an extremely serious emergency, requiring immediate medical help. The signs of anaphylactic shock are listed on p.58. In the case of food allergy, there are additional signs in the mouth, lips and throat (see p. 62). Use adrenaline (epinephrine) straight away if you have it – but get emergency medical help as well. With injectable adrenaline (an EpiPen or Anapen – see p. 150), remove the cap and jab firmly into the outer thigh, going straight through any clothing. Never inject into any other part of the body – this can be dangerous.
If you have an adrenaline inhaler (see pp. 155-6) you can use this first to treat symptoms in the mouth, throat and airways, and then use the injector if you still have symptoms. (Improvise a spacer – see p. 100 – if there is difficulty in inhaling the adrenaline.) Anyone whose reactions tend to be severe should use the injector first and follow up with the inhaler if necessary. Overdosing with adrenaline is possible, and can be fatal, but using the inhaler as well as the injector is safe as long as you don’t have a heart condition (see pp. 155-6).
If you do not improve after using the injector, a second one can be used, 10-15 minutes later.
In situations where medical help is not yet available and the symptoms are not abating, another shot of adrenaline can be given every 15-20 minutes. But the maximum number of shots recommended by your doctor should never be exceeded. Keep count of how many you’ve had, and tell medical staff.
An asthmatic who does not have an adrenaline inhaler can use a beta-2 reliever inhaler such as Ventolin (see p. 152) as well as the adrenaline injection, although it probably won’t help very much.
Suppose you know for sure that you have encountered your allergen, but you don’t have any symptoms yet? In Britain, the usual advice is to wait for symptoms, but doctors in the United States say go ahead and use the adrenaline injector if you have reacted very badly in the past. In general, for people with no other health problems, it is better to give an adrenaline injection which isn’t needed than to delay giving one that is needed. Delaying the use of the injector may mean that the reaction gets out of control. Some people put off using the injector because they think it should be saved for when they ‘really need it’. In fact the adrenaline works just as well if you have used it on previous occasions.
Following anaphylactic shock, you should be kept in hospital for 6-12 hours even when everything seems fine. Attacks have recurred as much as eight hours later. Corticosteroids reduce the chance of this happening – ask if these have been given. If you are discharged early and it is a long journey home, consider waiting in the hospital, or nearby, until eight hours after the original reaction.
First aid for anaphylactic shock
A badly swollen tongue or throat can cause suffocation. If there is visible swelling and the person is unconscious or turning blue, try to keep the top of the trachea (the main airway leading from the throat) open. Use the handle of a spoon – one that has very smooth edges. Slide it carefully over the top of the tongue and into the throat. Press down gently but firmly to open the airway.
Someone who is feeling faint or dizzy, or losing consciousness, or (in the case of a child) becoming very pale and floppy, may be suffering from a dangerous drop in blood pressure. He or she is more at risk of a fatal collapse if in an upright position, because not enough blood is reaching the heart. The worst thing is to stand up suddenly, or to move (or be moved) quickly from a lying to a sitting position –death can follow within seconds. The best thing is to lie down, preferably with the legs resting on cushions or a stool so that they are above the torso, and with the arms raised above the chest. Adrenaline can be given while in this position. A stretcher should be used to get the patient to an ambulance.
Latex allergy and emergency treatment
If you have anaphylaxis due to latex allergy, going to hospital can be alarming, as you may suffer further reactions to latex gloves or equipment. Some patients with latex allergy have had such bad experiences in ambulances and hospitals that they become fearful of using their adrenaline injector, since this means they must go to the hospital afterwards. They delay using the injector, which makes the situation worse. Some doctors are now giving such patients all the medicines and training they need to manage their anaphylactic shock themselves, so that they don’t need to attend hospital.
A person who has lost consciousness should be lying down on their side in case they are sick (this reduces the chance of them inhaling their vomit). The same goes for anyone who feels nauseous.
On the other hand, if the major problem at the outset is difficulty in breathing (as it generally is in children) a sitting position is better.
It is unusual for both faintness and severe breathing problems to be present at once. If this occurs, the patient should lie down, and if there is swelling in the throat, a spoon should be used (see left) to keep the airways open.
Insect-sting allergy
If you don’t have an adrenaline injector, get medical help immediately.
If you’ve had a cutaneous systemic reaction (see p. 60) in the past, use the adrenaline injector if there is any difficulty in breathing, hoarseness, stomach cramps, diarrhoea, nausea, faintness, dizziness or confusion. If you are unsure, remember that, unless you have a heart condition, it is usually better to overreact (i.e. use the adrenaline unnecessarily) than under-react.
If you’ve had a severe systemic reaction (i.e. anaphylactic shock) in the past, use an adrenaline injector at the first sign of any reaction other than immediately around the sting.
If there is a honeybee stinger left in the skin, scrape or flick it out sideways using a fingernail, knife blade or credit card – the venom sac is attached and will go on injecting venom for up to 10 minutes if you leave it there.
Don’t try to pull the stinger out – this squeezes the venom sac and pumps more venom into the skin.
Get emergency medical help, and follow the other measures for dealing with anaphylactic shock (see left).
Don’t go alone
If you suffer vomiting or diarrhoea during anaphylaxis, and have to go to the toilet, tell someone to call an ambulance and take someone else with youto the toilet. Do not go in alone and lock the door, in case you collapse.
Asthma attacks
Even those with mild asthma, who have never had a serious attack before, can quite suddenly get into difficulties and require emergency treatment. Don’t be over-anxious about this, because it is unlikely to happen – but do be prepared. Not having your reliever inhaler with you when a severe attack starts is a recipe for disaster – always take it, wherever you go.
Deal with an attack promptly. The sooner you act, the fewer drugs you’ll need in the long run to control the attack. Most asthmatics wait too long and then under-treat their asthma.
The important thing is recognising an asthma attack, and knowing when it is getting out of control. Not all attacks are the same – some come on fast, some come on slowly.
Rapid asthma attacks come on in a matter of hours. You may have been fine all day, but then start to feel very breathless and wheezy, or begin coughing badly. Less than an hour later, despite using the reliever, the breathlessness is worse and it is a struggle to speak or walk across the room. This is a severe attack: don’t delay in getting medical help.
Slow asthma attacks come on over a period of days. At first you are more breathless and wheezy than usual, and your reliever inhaler is not helping much. Asthma wakes you up at night, and you are far more breathless than usual in the morning. This could be the beginning of a severe attack, so don’t delay in getting medical help. If you get to the point where your asthma is disturbing your sleep every night, and in the morning you have difficulty in speaking or walking about, this is a very serious situation – you must see your doctor or go to the hospital now.
A few asthmatics have great difficulty recognising when they are increasingly breathless, and for them, using a peak-flow meter (see p. 97) every day is essential. Indeed, most asthmatics find
Recognising an asthma attack in a very young child
With a young child, these signs indicate a severe asthma attack:
• the nostrils are flared
• the shoulders are unusually high
• the child can say only one or two words between breaths
• the ribs are pushed out, and the spaces between the ribs, and below the chest cage, are sucked in during breathing
• you can hear wheezing (a whistling noise)
• the lips, tongue or fingernails are blue.
If wheezing stops, without any other apparent improvement, this is a very bad sign — it may mean that the airways are now so narrow that no air is passing through them. This is called a ’silent chest’, and indicates an urgent need for medical attention.
that monitoring peak flow is a valuable way of spotting attacks in advance. However, if your peak flow seems normal, and yet you feel breathless and have a tight feeling in your chest, pay attention to your symptoms and get medical help.
Your response to your reliever inhaler is another helpful sign assessing asthma attacks. Things are serious if:
• the reliever inhaler does not seem to be working at all within 10 minutes of taking a puff
• it does not work as well as usual
• it works, but the effect wears off in less than three hours. If you have an asthmatic child, give everyone who normally takes care of the child detailed written instructions for recognising and dealing with an asthma attack. People forget verbal instructions especially in an emergency. A child who is exhausted or upset c. an attack should always be given medical care.
Taking action
If your reliever inhaler is not working well (see above), take another puff to open up your airways – and then take further action. as described below.
If you seem to be in the early stages of a slow asthma attack check your management plan, and if your peak flow has fallen below the recommended level, double the dose of inhaled steroids (twice as many puffs each time) now. Add any other medicines (e.g. steroid tablets) as recommended by the management plan.
Those who don’t have a peak-flow meter or management plan should double the dose of inhaled steroids and make an urgent appointment to see the doctor.
If you are suffering a rapid attack, or a slow attack that has got out of control, you need emergency medical help. Ring for an ambulance, ring your doctor, or go to the hospital – the ideal course of action will vary, depending on where you live (see p. 98).
Use your reliever inhaler until medical help arrives. You can take a puff every 5-10 minutes if needed, but keep a count of how many puffs you’ve had and stop after 30. Some doctors suggest taking up to 30 puffs all at once. (If you have a heart condition, this dose might be dangerous: follow your doctor’s advice.)
If it is difficult to inhale, use a spacer – this can make all the difference, especially for children.
You can improvise a spacer from a plastic cup, a plastic bottle, or a paper bag. Make a hole in the bottom of the cup or bottle, or in one corner of the paper bag, and insert the mouthpiece of the inhaler here. The open end of the cup, bottle or bag goes in or over the mouth – with the bag, you have to bunch it up and hold it around the mouth. Squirt the inhaler repeatedly into the improvised spacer, while breathing steadily in and out.
The six golden rules for asthma attacks
• Breathe as slowly as possible and concentrate on breathing out, not on breathing in. Exhale as fully as you can and your in-breath will follow automatically.
• Never panic – if you do, you may start hyperventilating, and this makes matters much worse (see p. 226). Panicky parents are the worst possible thing for an asthmatic child during an attack.
• Adopt a position that makes breathing as easy as possible. Propping your arms up at about shoulder height can help – for example, sit back-to-front on a dining chair, with your arms folded and resting on the back. Or put pillows on a table, sit in an upright chair, and rest your head and arms on the pillows. Don’t lie down, as this makes matters worse. Open a window, as long as the air outside is not cold, polluted or loaded with pollen.
• Avoid factors that can make an asthma attack worse, for example, vigorous activity, cold air, irritants and allergens.
• Drink plenty of water, fruit juice or other liquids as a lot of water is lost through the surface of the airways during an asthma attack, and you can become dehydrated.
• Don’t take anything to help you sleep, even herbal pills. If your asthma gets worse during the night, you need to wake up so that you can get more air.
After an attack
Asthmatics who have suffered a severe attack are occasionally sent home from hospital before they are completely better. A few people have died as a result of being discharged too soon. So if you feel breathless or otherwise unwell after you leave hospital, don’t hesitate to go back – or seek other medical help.
See your GP or specialist within a few days of any emergency treatment. Don’t be over-confident just after a severe attack – this can be a very vulnerable time. Take more rest than usual and drink plenty of fluids, as you may be dehydrated. Keep taking your preventer inhaler at the increased dose – reducing the dose now could lead to another severe, possibly fatal, attack. Keep taking steroid tablets if you have been given them.
If you produced a lot of mucus during the attack, try to clear it, but without violent coughing. Mucus can sometimes form solid plugs which block small airways. Treatment by a physiotherapist would help, and expectorants – drugs which help loosen mucus –can also be useful (ask your pharmacist about these). Don’t take ordinary cough medicine (see box on p. 163). There are also some breathing exercises which can help to clear mucus (see p. 231).
An asthma attack represents a chance to learn more about preventing asthma – so think about what went wrong. Had you forgotten to take your preventer inhaler regularly? How long is it since you had your medicines reviewed by the doctor or asthma clinic? Have you been using your peak-flow meter daily? Were you exposed to a high dose of allergen or an irritant?
A reaction to aspirin-like drugs
Aspirin sensitivity can begin quite suddenly in someone who has previously taken aspirin without trouble. If you have unexplained chronic urticaria, or polyps in the nose, plus asthma and/or rhinitis, the development of aspirin sensitivity at some time in the future is a distinct possibility (see p. 151).
A sensitivity reaction to aspirin or aspirin-like drugs usually begins between 30 minutes and two hours after the drug is taken. You will have some or all of these symptoms:
• a runny or badly blocked nose, and red eyes
• a feeling of warmth, flushing and sweating
• a general rash
• a sensation of tightness in the chest, a dry cough, increasing breathlessness
• malaise and exhaustion
• vomiting or diarrhoea
• swelling (angioedema) and/or nettle rash (urticaria). If you have such symptoms get emergency medical help immediately because the reaction can quickly develop into severe asthma, shock, collapse and unconsciousness.
If you have asthma, use your reliever inhaler as much as required (up to 30 puffs) until medical help arrives. Anyone who has an adrenaline (epinephrine) auto-injector, or an adrenaline inhaler, can use this as well – up to 30 puffs of the inhaler, or whatever maximum dose is given in the instructions. Tell the ambulance crew and doctors exactly what you have taken.

Allergy and Your Immune System
`The summer used to be such a miserable time for me because I’m allergic to grass pollen. For most of

my life I have had dreadful hayfever, and my asthma would get worse during the summer as well.

Antihistamines knocked me for six, and although there were nose drops that helped a little, they

certainly did not resolve the problem completely. Exam time was always a nightmare when I was a student

- then, as now, it coincided exactly with the pollen season.’
‘Getting a job in Chicago was a turning point in my health. My colleagues were amazed to see me

snuffling through the summer and just accepting that nothing could be done to improve matters. The

whole approach to treating allergies is different there. Eventually someone marched me off to see her

allergist, who said that I should have “allergy shots” and that my health insurance would cover it. The

process was very time-consuming at first, and it took a while to work, but the change is remarkable.

I’ve never regretted having the treatment. Summer is a time I can actually enjoy now.’
Not everyone responds this well to immunotherapy, but for those allergy sufferers who do benefit, this

is an excellent treatment. It tackles allergies right at their source, by teaching the immune system to

react differently to the allergen.
Also known as Specific Immunotherapy (SIT), Incremental Immunotherapy (11T) or simply as

hyposensitisation, this form of treatment was devised by two English medical researchers, Leonard Noon

and John Freeman, who reported their successes with hayfever patients in 1911. Ironically, their

treatment is now less readily available in Britain than in any other industrialised nation. Only a

small minority of British allergy patients receive immunotherapy. The cause of this strange situation

is a ruling made in 1986 by the Committee on the Safety of Medicines (CSM). This states that

immunotherapy must only be given where there is resuscitation equipment available, and that all

patients must wait for an hour after each injection, in case of
side effects. In addition, immunotherapy cannot be used for severe asthma.
The requirement for resuscitation equipment rules out most GP surgeries, and this effectively puts

immunotherapy beyond the reach of many allergic individuals in Britain, owing to the extreme shortage

of allergists and hospital allergy clinics (see p. 89). (In the past, the lack of allergy specialists

meant that most immunotherapy in Britain was given by GPs.)
The CSM ruling was triggered by a number of deaths due to immunotherapy: there were eleven fatalities

between 1980 and 1986, with five of these in the eighteen months just before the report. But almost all

these deaths were due to very basic errors in the way the injections were given – tragic as the deaths

were, the official response to them was inappropriate. Fatal reactions to immunotherapy can be avoided

with close attention to ordinary safeguards (see p. 166-7).
Allergen immunotherapy is still freely available elsewhere in the world, and is regarded as a key part

of allergy treatment. Britain is now out of step with all other developed countries, and most doctors

feel that British restrictions are far too strict.
There are hopes that this situation may change within the next few years, and that more allergy

sufferers may be able to take advantage of this valuable treatment. This could be achieved, in part, by

investing more National Health Service money in allergy clinics and allergy specialists. In addition,

there should be a relaxation of the regulations, so that properly trained GPs can give immunotherapy to

patients who are not at high risk of a fatal reaction. For people whose lives are affected by

allergies, the reintroduction of this treatment (with appropriate safeguards) would be a huge boon.
The uses of immunotherapy
Immunotherapy is mainly used for airborne allergens such as pollen, house-dust mite and mould spores.

Allergies to animals can also be treated with immunotherapy, but the treatment cannot work miracles –

if a cat-allergic person decides to keep the cat, the high dose of allergen inhaled every day limits

the impact of immunotherapy treatment.
People with straightforward allergic reactions affecting the nose and eyes (allergic rhinitis and

conjunctivitis) respond well to immunotherapy. In patients with hayfever, for example, the success rate

(patients showing some degree of improvement) is about 80-90%. When nasal allergies are complicated by

chronic sinusitis or nasal polyps, the chance of success is a little lower.
Some studies of the long-term effects of immunotherapy suggest that, if it is given to children with

hayfever or perennial rhinitis, those children are less likely to develop asthma.
The benefits of using immunotherapy to treat established asthma are less certain. Asthma is a more

complex disease than hayfever, and allergies are only one factor among many (see p. 36), which may

limit the impact that immunotherapy can make. Experience suggests that immunotherapy can be a great

help for an asthmatic with a strong allergic reaction to a single airborne allergen, such as grass

pollen or house-dust mite, but not for other asthmatics. Asthmatics with aspirin sensitivity or chronic

sinusitis are unlikely to benefit.
The value of immunotherapy to children with asthma is a subject of great debate among doctors in the

United States. Some studies suggest that it is of little real benefit, while others are more positive.

One interesting study, that followed asthmatic children for 15 years or more, found that if they were

given a full five-year course of immunotherapy when young, they tended to have fewer asthma symptoms

and need less medication in their late teens and early twenties.
Chronic urticaria (nettle rash) is occasionally due to airborne allergens, in which case immunotherapy

may help. However, immunotherapy is not recommended for atopic eczema. When people with both eczema and

rhinitis try immunotherapy for their nasal allergies, some find that their eczema gets worse.
Insect-sting allergy is a prime candidate for immunotherapy (see pp. 167-8) but food allergy is a

different matter, and is not treated with immunotherapy at present (see p. 168).
Who can get immunotherapy?
As a result of the CSM ruling (see p. 164) remarkably few allergy sufferers in Britain receive

immunotherapy.
Those with insect-sting allergy, who have suffered anaphylaxis (see p. 58), are the most likely to be

offered this treatment. However, even with this frightening and life-threatening problem, which can be

treated with almost 100% success by immunotherapy (see p. 167-8), such treatment is not automatically

available.
A few people with severe hayfever that does not respond well to drug treatment may also be given

immunotherapy. It is worth asking your doctor about such treatment if you feel you would benefit.
How immunotherapy works
Immunotherapy consists of a series of small injections, just under the skin. The liquid that is

injected contains an extract of the offending allergen, for example house-dust mite. The injections are

given at regular intervals, usually once a week, although other schedules are possible (see p. 167-8).
At the outset, a very dilute version of the allergen extract is used, way below the threshold for an

allergic reaction. People who seem highly sensitive, on the basis of their skin tests, start on an

extract that is even more dilute.
For the next injection, a slightly higher concentration of the allergen extract is used, and the

concentration goes on increasing with each successive injection. The idea is to habituate the immune

system to the offending allergen, by very gradually raising the dose. Eventually, when the dose reaches

a level which generally gives beneficial effects, no further increases are made.
If an allergy sufferer reacts badly to immunotherapy injections (see p. 166) on several successive

occasions, the dose may be levelled off before the ideal maximum dose is reached. However, a good

allergist will persist for some time in trying to increase the dose because stopping at a lower level

often results in the treatment being ineffective.
The first stage of immunotherapy, when the concentration of allergen is being increased week by week,

is referred to as the build-up stage. The second stage, when the dose is being kept at the same level,

is called maintenance therapy, and the dose used is the maintenance dose.
There is sometimes an obvious improvement by the time the build-up stage is complete, but not always.

The benefits of the treatment generally appear within six months of reaching the maintenance dose, but

some people have to wait a year or even two before things improve. As the immunotherapy begins to take

effect, symptoms decline and there is often less need for drugs.
A great deal of research effort has gone into finding out what lies behind these changes – in other

words, what is actually happening to the immune system when immunotherapy is effective. The answer is

that a surprising number of different changes may occur and no two allergy sufferers react to

immunotherapy in quite the same way. Frequently there is a shift in the kinds of antibodies the body

produces against the offending allergen. Levels of IgG antibodies (which help to block the allergic

reaction) go up, while levels of the allergy antibody, IgE, tend to stabilise and eventually go down.

The numbers of mast cells (see box on p. 12) may also decline, and they can become less responsive to

the allergen. The balance of power between Th1 cells and Th2 cells may also shift, with the pro-allergy

Th2 cells (see p. 11) becoming less influential.
What can go wrong
The secret of safe immunotherapy is to go at exactly the right speed for the immune system of the

individual being treated. The doctor should look for feedback from the immune system – signs that show

how well it is coping with the steadily increasing dose of allergen – and use these to pace the

immunotherapy schedule.
Going too fast – getting ahead of the immune system’s ability to cope – is hazardous. A major allergic

reaction, called anaphylaxis (see p. 58), can occur, and this is the cause of deaths during

immunotherapy. However, as long as there is injectable adrenaline (see p. 150) and resuscitation

equipment available, even such an extreme crisis can be dealt with safely.
Serious reactions to immunotherapy usually occur:
•    during the initial build-up phase; maintenance therapy is much safer
•    during the pollen season, for those with pollen allergy
•    when a new vial of allergen extract is first being used, because of variations in concentration

(see p. 168-9).
Those most vulnerable to severe reactions are:
•    people with asthma, especially severe or unstable asthma
•    those who have experienced systemic allergic reactions in the past
•    anyone who appears to be extremely allergic, on the basis of skin tests
•    anyone taking beta-Mockers (see box on p. 150).
With care, these fatalities can be avoided. Patients who are given immunotherapy can ensure their own

safety by being well informed about the procedure (see p. 167).
The timing of immunotherapy
There are various different approaches to the timing of immurotherapy. The basic method (which has a

good safety record in the United States where it is very commonly used) starts with injections once a

week. After the maintenance dose has been reached, maintenance injections are given once every 2-4

weeks. The frequency of these may be increased during the pollen season, for people with pollen

allergies.
It is the regularity of the injection schedule that gradually creates, and then sustains, immune

tolerance, so the treatment is only of value to patients who can reliably keep their appointments.
When immunotherapy is successful, it can eventually be discontinued without any reappearance of the

allergic reaction. It usually takes 4-5 years of regular therapy, from the time of the first injection,

to get to this point. The benefits then persist for many years, perhaps indefinitely in some people,

even without any further injections.
Rush immunotherapy
Trying to speed up the process of immunotherapy greatly increases the risk of a severe reaction

(anaphylaxis). However, there are some situations where fast results are needed, and in such cases rush

immunotherapy, also called accelerated immunotherapy, may be used.
During the build-up stage of rush immunotherapy, injections are given every day, or even several times

a day. All the usual safety procedures (see below) are observed with particular care, to reduce the

chance of a severe reaction.
In semi-rush immunotherapy, the build-up injections are given twice a week, and the risks are lower

than with daily injections, but still higher than with weekly injections.
Minimising the risks
If you are lucky enough to be offered immunotherapy treatment under the National Health Service, you

should not feel concerned about accepting the offer. There is very little risk of a bad reaction

because safety procedures are now so stringent.
To minimise the risk of suffering a severe reaction, the doctor will ask you, at each visit, about any

reactions that occurred after your previous injection. Reactions might include redness, itching or

swelling around the injection site, or (more seriously) symptoms elsewhere on the body, such as nettle

rash (urticaria), itchy skin, sneezing, a runny nose, red or itchy eyes, tightness in the throat or

chest, coughing or wheezing. Always make a note of such symptoms, so that you don’t forget to mention

them at the next visit. This is crucially important, as such reactions can indicate that the immune

system is being hurried along too fast.
The doctor will also ask if you have an infection of any kind, as this can alter your reaction. You

should also tell the doctor about any new medicines being taken, as some, such as betablockers (see box

on p. 150), can make a bad reaction to the injection more likely to occur.
Asthmatics can expect the doctor to ask about current asthma symptoms, and to check their peak flow

both before and after an injection. If there are any symptoms, or if the peak flow is less than 70% of

the best-ever value, the injection won’t be given.
Severe reactions can sometimes begin several hours after the injection, so stay within reach of a phone

for about 24 hours. Among United States allergists (who don’t require their patients to wait after the

injection for more than 20-30 minutes) there are some who believe that everyone undergoing

immunotherapy should carry an adrenaline (epinephrine) auto-injector (see p. 150) on the day an

injection has been given, for use in the event of a severe reaction. Anyone who has suffered

anaphylaxis in response to an insect sting will probably have an adrenaline auto-injector anyway, and

this can certainly be used to treat anaphylaxis following immunotherapy. Note, however, that using the

adrenaline is just the first step in treating anaphylaxis (see p. 98) and you must then go back to your

allergist, or to the nearest hospital emergency department, without any delay.
It is sensible to avoid exercise for two hours after an injection. Be extra-cautious during the pollen

season if you are receiving immunotherapy for pollen allergies.
Immunotherapy for insect-sting allergy
`Our daughter has had two really bad reactions from being stung by a wasp. After the second one, the

doctor at the accident and emergency department told us that she nearly died. We got so anxious about

it that we worried every time we left the house in the summer, and it was even worse if she went out

without us. My wife got so upset about it that she wasn’t sleeping well. It was affecting the whole

family badly.
‘Then we heard about desensitisation treatment, and asked our GP, but he said he couldn’t do it.

According to him, they might be able to do it at the hospital, but it might not work, and it was risky

too. We accepted that at first, but then I started doing some research on the Internet, and discovered

that in America and Germany this treatment is absolutely standard – someone like our daughter would

automatically be given it. We felt very angry when we found this out, and went back to the doctor.

Eventually Ann was referred to the allergy department at a hospital, and now she is getting this

desensitisation treatment. I’m pleased about that, obviously, but I still think it shouldn’t have been

such a fight to get it.’
Immunotherapy provides highly effective protection for those with insect-sting allergy, and should be

given to anyone who has had a severe systemic reaction (see p. 60). Some United States allergists also

recommend it for adults who have had a cutaneous systemic reaction (see p. 60), on the basis that they

may well progress to a severe systemic reaction with the next sting.
Studies of people who have suffered severe systemic reactions, and are then treated with immunotherapy,

show that 97% have no systemic reaction to future insect stings. For the 3% who are not fully

protected, the severity of the reaction is much reduced and far less likely to be life-threatening. In

other words, this is an excellent treatment which can save lives.
Targeting the treatment
Choosing the right venom for immunotherapy can sometimes be difficult. Not everyone with insect-sting

allergy sees the insect that caused the reaction. Skin tests may not give the answer either, because

there are often positive reactions to several different venoms. Some of these may be false positives

(see box on p. 91) and it is impossible for the allergist to say which one(s) are actually relevant.

Most allergists will recommend immunotherapy for all of them, using a mixture of venom extracts.
Where the guilty insect was seen and identified, but other venoms also give positive skin tests, a more

difficult decision has to be made. Many allergists carry out immunotherapy for all the venoms that gave

a positive skin test, on a ‘better safe than sorry’ basis. Since there are cross-reactions between

venoms (see box on p. 113), there is some sense in this. Other allergists just give immunotherapy for

the insect that did the deed.
Will immunotherapy against one insect protect against a related insect? With two closely related

insects such as wasps and hornets, which have many allergens in common, it might do – but there is no

guarantee. The problem is that, as well as the shared allergens, each venom also has its own unique

ingredients. It’s impossible to say, with the kind of tests available at present, if an allergic

reaction was to shared allergens or unique ones. So immunotherapy against wasp venom may give

protection against hornet venom, but it will not necessarily do so – and vice versa.
In the case of bumblebee allergy (seen almost exclusively in those, such as horticulturalists, whose

work involves handling bumblebees) a more definite answer can be given – honeybee immunotherapy does

not work. Immunotherapy with bumblebee venom does work, fortunately. The bumblebee extract has to be

obtained from specialist sources.
Injections are given weekly during the build-up phase, unless protection is needed urgently, as with

work-related sting allergy, in which case rush immunotherapy may be used. Once the maximum dose has

been reached, a maintenance injection is needed every four weeks. After a year, this maintenance dose

can be given every 6-8 weeks.
After 3-5 years of immunotherapy, skin tests with insect venoms are usually tried again. If the results

are negative, the immunotherapy will stop. Research now shows that, even if skin tests are still

positive when immunotherapy ends, there’s an 8090% chance that no systemic reaction will occur to

future stings. Some people are not reassured by this, and prefer to continue with immunotherapy for

their own peace of mind. Indeed, research shows that a near-fatal systemic reaction has a long-lasting

psychological impact, and that many people continue to feel anxious despite completing immunotherapy

and reacting negatively to skin tests.
At one time, challenge stings with live insects were given to check whether immunotherapy had actually

worked. Few doctors do this now, but your allergist may be prepared to do a challenge test if you ask.

Adrenaline and resuscitation equipment would be available if a challenge test were used, so any severe

reaction could be dealt with promptly and effectively. The fact that the psychological consequences of

insect-sting allergy are so persistent suggests that challenge tests with live insects may have a

particular value, in demonstrating that immunotherapy has worked. Challenge tests are also helpful for

those who work with stinging insects, such as honeybees and bumblebees, and who need to be sure that

they can go back to work safely.
Immunotherapy for food allergy?
Attempts to use standard immunotherapy for food allergy have been made repeatedly, but without success.

The process of giving the injections is nerve-racking because of the constant risk of a severe

reaction. The risks prevent the dose of allergen being increased very much, so the beneficial effects

are small. While there may be some reduction insensitivity, it is not enough – or not reliable enough –

to be of any practical value.
What doctors are aiming for here, incidentally, is simply to protect against the effects of

accidentally eating a tiny amount of the food – no one is expecting that someone with peanut allergy

will be able to eat peanut butter sandwiches as a result.
Some of the new developments in immunotherapy may be useful for food allergy, as described in the next

section.
The future of immunotherapy
Many different research teams are working on ways of improving immunotherapy – making it more

effective, safer to give, and less time-consuming.
One approach involves altering the allergen, so that it only interacts with those parts of the immune

system whose job is to control allergic reactions (and therefore bring about tolerance). The changes

made to the allergen are designed to make it ‘invisible’ to the parts of the immune system that

actually attack the allergen. The idea is to inject something that can’t cause a bad reaction, and is

therefore 100% safe.
The modified allergens are called allergoids. Another term often used is peptide immunotherapy – this

describes a technique in which the allergens are chopped up into small pieces to make them safe

(allergens are proteins, and a fragment of a protein is called a peptide).
Already, researchers in Germany have made an allergoid from birch pollen that can reduce hayfever

symptoms with a series of just seven injections given before the pollen season.
Meanwhile, a research team in London is working on peptides made from cat allergen, with encouraging

results so far. In a group of asthmatics who were allergic to cats, a series of 4-10 injections, over a

period of 2-8 weeks, produced benefits in about half those treated. The researchers believe that they

can improve on this and help the majority of people with cat allergy, at least enough to survive

temporary exposure to cat allergen (when visiting cat-owning friends, for example). They hope to refine

the treatment sufficiently to enable some cat-allergic people to keep their pet, rather than finding it

a new home. This is a relatively safe treatment that might be given by a GP, rather than only by

specialists. The research team hopes the treatment will be available by about 2009.
Could this kind of technique work for food allergy? Doctors believe that it can, and a great deal of

research work is being done, in both Britain and the United States. A major focus of this effort is

peanut allergy, since this puts so many young lives at risk. Even if the research is successful, It

will be several years before such treatments become available.
Researchers are also working hard to produce standardised allergen extracts – in other words, allergen

extracts that always contain a standard amount of the allergen. The aim is not only to reduce the

number of treatment failures (which can occur if the extract does not contain enough allergen) but also

to avoid mishaps when a new vial of allergen extract is used (differences in strength, between one vial

and another, are sometimes a cause of anaphylactic reactions).
Standardisation is difficult, because the starting materials –skin particles from horses, for example,

or dust-mite droppings –are natural materials and therefore variable. Some samples contain far more of

a particular allergenic ingredient than others.
One way around this problem is to develop accurate methods of measuring the amount of allergen in the

extract. Another approach is to abandon the whole business of making extracts, and produce allergens

artificially, in a laboratory. This is done by inserting the gene for the allergen – the gene for the

Der p1 allergen of house-dust mite, for example – into bacteria. These bacteria then act as production

units, manufacturing large amounts of the allergen every day. With this high-tech approach, the exact

content of the allergen preparations can be controlled.
These high-tech allergen preparations are extremely pure, and therefore very effective – as long as the

person receiving immunotherapy really is sensitised to the particular allergen that is included.

Unfortunately, most natural allergenic materials contain two, three or even more separate allergens. In

house-dust mite droppings, for example, while Der p1 is the allergen that affects most people, there is

also an allergen called Der p2, and a few people are more sensitive to this than to Der pl.
Artificially produced allergen preparations usually include the main allergen only. For the minority of

people who are more severely allergic to one of the other allergens, this extract will not work.

Eventually this problem will no doubt be circumvented by means of more precise skin testing before

immunotherapy begins – skin tests with individual allergens, rather than with allergen extract

containing a mix of allergens.
A third approach is to change from injections to oral immunotherapy – giving the allergen extracts by

mouth. The best results are obtained when the allergen is held under the tongue for a while and then

swallowed. This is known as Sub-lingual immunotherapy or SLIT, and has become very popular in Italy and

France, where it is a common treatment for hayfever. A recent pilot trial among GPs in Britain suggests

that it may be useful, but is not a miracle cure. Overall, the group treated with SLIT had fewer

symptoms during the pollen season, but antihistamines were still needed. There is some evidence from

Italy that SLIT might reduce the likelihood of children with hayfever going on to develop asthma, and

reduce the chance of new sensitivities.
Side effects are unusual with this treatment, and those that do occur are mostly mild – itching in the

mouth, for example. The treatment is safe enough for routine use in children.
Might oral immunotherapy work for food allergy? Other Italian studies suggest that it could. The

objective of these studies is to reduce the risk to children with cow’s-milk allergy from accidental

encounters with ‘hidden milk’ in prepared food or drink. The immunotherapy treatment begins with

miniscule amounts of milk – the doctors start with a single drop diluted in water, each day for a week

– and increase the dose extremely slowly. Antihistamines are given to minimise the risk of a reaction.
The whole process requires enormous patience, but after seven months, the majority of the children

involved can tolerate some milk – between three tablespoonfuls and a small cupful each day.
This is a very encouraging study that should be repeated by doctors in Britain. Because of the risks of

anaphylaxis – which can, of course, be fatal – it does require full medical supervision, and you should

not attempt it at home. Whether this method would work for allergens other than milk is something that

nobody has yet investigated.
A great many other approaches to immunotherapy are currently being tried for food allergy. Many of the

new techniques are highly experimental, and some show great promise, but it will be many years before

they are in use.
One innovation that is closer to being in general use in the United States involves giving the anti-IgE

drug omalizumab (see p. 149) alongside immunotherapy injections. The drug maximises the benefits from

the immunotherapy, and may make the build-up stage (see p. 165) safer, by lowering the risk of

anaphylaxis. For British allergy sufferers, who cannot yet get omalizumab, and whose chances of getting

immunotherapy are vanishingly small, it may seem unkind even to mention such treatments, but we can

only hope that things will improve here in the near future. You might take some comfort from the

thought that, by the time immunotherapy is available again in Britain, there will be a whole host of

highly effective new techniques available for doctors to try.
All the methods described above are forms of specific immunotherapy – they treat an allergy to dust

mites or to grass pollen or some other specific allergen.
A far more radical and ambitious approach to immunotherapy is now the aim of some medical researchers:

blocking the tendency to allergies as a whole.The underlying idea here is to reverse the basic shift in

the immune response, from Th1 cells to Th2 cells. It is this shift to Th2 cells which produces the

allergic tendency (see pp. 11 –13).
Some interesting findings have already been made in this area, including the surprising discovery that

the balance of Th1 cells and Th2 cells can be adjusted even in people with longstanding allergies.

Inspired by discoveries about hygiene and allergy (see p. 21), British researchers have made a vaccine

containing inactivated cells of a harmless bacterium found in the soil, Mycobacterium vaccae. This is

given as a single injection just under the surface of the skin. It has been used for adult patients

with asthma, and for children with severe atopic eczema, with some improvement in both groups. If the

treatment proves as useful as the preliminary studies suggest, this could be a common treatment in a

few years’ time.