Posts Tagged ‘House-dust’

Because house-dust mites are a major source of allergic reactions they have been studied intensively, and various ways of killing them devised. But simply killing the mites is not enough. Their allergens will remain, and continue to cause allergic reactions for years. The allergens have to be either removed or inactivated — that is, changed chemically so that they are no longer recognised by the immune system.
Tackling dust mite is easier if you know certain key facts:
1 Dust mites prefer humid conditions. They do not drink, but absorb water from the air. When the relative humidity falls below 50%, the mites gradually dry out and are killed.
2 Mites feed on our skin scales, but only if they have been broken down first by moulds. High humidity (70-90% relative humidity) is a particular problem, for anyone with an allergy to house-dust mites, because it favours the mould that suits dust mites best.
3 Dust mites live inside mattresses, pillows, upholstery, cushions and soft toys. The allergens are blasted out when you settle into an armchair, get into bed, or turn over in the night.
This is when you inhale the biggest dose of allergen, or get the maximum dose to your skin. Carpets also contain dust mites, but the numbers are generally lower.
4 Dust-mite allergen is relatively heavy, compared to cat or mould allergens for example. Little of it floats around in the air, and the most significant exposure is inhaling it close to the source — from a pillow, mattress or teddy bear. This is why air filters are of little value for anyone with dust-mite allergy.
5 Dust mites are everywhere, and are carried around in clothing. Even if you could eliminate all the mites from your house, new ones would soon appear. A new mattress will usually be colonised by dust mites within four months.
The size of the allergen particles
The droppings of the dust mite, not the mites themselves, are the main cause of symptoms. The droppings are 4-20 microns in size, but they can crumble into fragments of 1-3 microns, and the tiniest bits are only 0.5 microns across. The pores of mite-proof covers (which really means mite-allergen-proof) should be less than one micron across, and preferably less than 0.5 microns. Dust masks (see p. 109) should also filter out particles of this size to be effective. The mites themselves are much bigger, 200-300 microns long, (A micron is one thousandth of a millimetre.)
The basics of mite warfare
• A temperature just above boiling point kills dust mites and inactivates Der pl, which is the troublesome allergen for most asthmatics. However Der p2, the other mite allergen, is not affected by heat. (Note that the carpet treatments advertised as ’steam cleaning’ generally just use hot soapy water, not steam. Because they leave the carpet very damp, they can increase the numbers of dust mites.)
• Washing with detergent at 55′C (130′1 or above (i.e. a 60′C wash cycle) kills mites and removes the allergen.
• Cooler washes will not kill mites, but will remove the allergen. This can be useful if the mites have already been killed by some other means. Regular cool washes of clothing or sheets will also remove human skin scales, reducing the mites’ food supply. (This is beneficial if you have eczema, because flaking skin adds to the problem by giving dust mites even more to eat.)
• You can buy mite-killing substances (see p. 255) to add to cooler washes, so that the mites are killed - the chemicals are rinsed out at the end of the wash, so are pretty safe.
• Dry-cleaning kills mites and it removes some of the allergen, but the amount removed is variable (20-70%).
• Freezing for more than six hours kills mites. Three hours’ strong direct sunlight in dry air will kill mites living in rugs and blankets. Neither treatment removes allergen.
• Mites hang on to the carpet fibres when the vacuum cleaner passes overhead, and about 65% of them remain afterwards. An ordinary vacuum cleaner sprays mite allergen into the air as it goes. The amount in the air - and therefore available to be inhaled - is three times higher after vacuuming.
Combating mites
Bear in mind that mites are the enemy - not dust itself. A house may be thick with dust but, because the windows are open a lot and the air is dry, it will have few mites. Another house may look perfectly clean, but be seething with mites because it is thoroughly draught-proofed, warm and slightly humid. The mites will be thriving in the carpets, beds and upholstery. Vacuuming and dusting every day, if done with an ordinary type of vacuum cleaner and a dry duster, will stir up the allergens and ensure that the air is full of them. So a person with mite allergy would feel far worse in the apparently very clean house than in the dusty one.
One crucial aspect of a mite-reduction programme is making the air drier - see p. 119 - so that mites no longer flourish.
Most of the other measures - described below - will involve stirring up dust-mite allergens, so the allergic person should not do the work, nor be in the house (see p. 109).
Too dry or too moist?
It is a well-established fact that the air in most modern houses is too humid, encouraging dust mites and moulds. Yet many people fit humidifiers because they believe that the air is ‘too dry’ and that this irritates the nose. Some very good scientific studies have shown it is indoor pollutants plus overheating that is the problem here, not dryness - even very dry air is not irritating as long as it is clean. Should your nose feel dry and ticklish, try to reduce indoor pollution (see pp. 128-9).
It is true that during an asthma attack, dry air does make matters worse, and very moist air helps. Inhaling steam from a bowl of hot water can be used to ease the attack.
The bed
Begin with the bed because this is the main exposure zone. A Danish study showed that just fitting mite-allergen-proof covers to the mattresses and pillows of dust-allergic children worked well. After a year the children had much less asthma at night, used half as much inhaled steroid, and gave better peak-flow readings.
The best approach is to buy a new mattress and new pillows before putting anti-mite coverings on them. These covers keep skin scales and mites out, which should prevent a new mattress or pillow becoming recolonised. The modern covers have tiny pores which allow perspiration to evaporate - this makes them comfortable to sleep on.
These pores are small enough (see box on p. 114) to keep any mite allergens inside, so they will also work with an old mattress, keeping the existing allergen inside. But the mites themselves will also thrive inside (there’s enough old skin there to keep them in business for years) and there is always the risk that, if a small tear develops, the stores of allergen in the mattress will come pouring out again. So start with a new mattress if you can.
Another possible option is to arrange for a contractor to heat-treat the bed, the mattress and all bedding. This is a new specialist treatment (see p. 255), where the bed is enclosed in a plastic tent and heated to very high temperatures. It is designed to kill all mites, even those right inside the mattress, and inactivate the allergen. (The contractor can also do your living room suite.)
If the covers are for a small child, check with the manufacturer that they pose no threat of suffocation. Mattresses and bedding with built-in covers may be safer.
Buy a new duvet (or wash or dry-clean your existing one) and put an anti-mite cover on it. Alternatively, buy a duvet and pillow that can be washed at 60′C (130′F), and wash them once a month. You must have the use of a tumble dryer, because mites will flourish if bedding is not completely dry.
An upholstered bed base will have its own (much smaller) population of mites. Buy a simple wooden or metal bed frame if possible. Or you could enclose the upholstered base in a mite-proof cover, or in plastic sheeting completely sealed with heavy-duty tape.
Wash all sheets and blankets at 60°C or more, or have blankets dry-cleaned – or buy new ones. From now on, wash sheets once a week and blankets once every two weeks.
Get rid of any other bedding such as patchwork quilts or fleecy underblankets. Alternatively, you can wash or dry-clean them regularly.
Electric blankets can be cleared of mites by washing them, and are very useful in keeping the bed free from moisture. This prevents mites from setting up home in the outer surface of your new mite-proof covers, so that you don’t need to wash the covers, sheets and underblankets so frequently. Leave the electric blanket on at a high setting, with the bed made, for at least twelve hours (check that there is no fire risk first). Note that some mite-proof covers might be damaged by this procedure – check with the manufacturer. If you have not yet purchased mite-proof covers, there are some made from Egyptian cotton which can tolerate this level of heat without damage (see p. 255).
Children’s beds and toys
Where children share a room, all the beds and bedding should be dealt with. Even then, an asthmatic child should never sleep in the lower half of a bunk bed, because mite allergens will shower down from the bed above.
Ali soft toys should spend at least six hours in the freezer once a week, to kill the mites. The first time, wash the toys
immediately afterwards to remove any existing allergen and dry thoroughly in a tumble dryer.
A hot wash, or the freezing/washing treatment, should also be used for ‘comfort blankets’, dressing-up clothes, dolls’ clothes and any other fabric items.
Sheepskins, sometimes used for babies’ cots, especial,. New Zealand and Australia, contain huge amounts of dust-mite allergen. It is advisable to discard these.
The next steps
Clothing is often full of mites, especially sweaters, coats and woollen trousers. Dry-clean all such items, or wash using a m –e-killing wash, then store them in a well-heated place so that they are always very dry.
Dandruff consists of skin flakes, and may help to feed mites Using an anti-dandruff shampoo may help. Semen also gives mites nourishment.
From now on, be careful about exposing your airways to dust. Get someone else to empty the vacuum cleaner bag – and they should, of course, do it outdoors. If you are stripping wallpaper, wash it down first to remove dust. Moving house, going into the attic, spring cleaning, turning out cupboards or moving furniture should all be avoided – unless you have a good mask on.
Do not use fan-heaters or convector heaters which churn up mite allergens from the carpet. Seal off any hot-air ducts from centralised heating systems, as these blow mite allergens around the room.
If possible, invest in a vacuum cleaner that keeps in all the allergens, or vents them outside, rather than spraying them out into the air. Make sure that the vacuum cleaner you buy really
What about sprays?
Chemicals that kill mites (known collectively as acaricides) are sometimes useful but have various limitations. They do not penetrate inside upholstered furniture, cushions or mattresses, so make little difference to the total population of dust mites. Even on carpets, sprays won’t reach most of the mites unless you rub the spray in really hard. (And ‘anti-mite’ carpet shampoos are completely ineffective.)
The safest chemical is benzyl benzoate — so safe that it is used directly on the skin for treating scabies infections. It can cause skin irritation at these doses, but rarely does so at the concentrations used in anti-mite sprays.
However, the idea of constant spraying, over a period of months or years, is worrying. Doctors generally advise against spraying bedding, and carpets or furniture where babies or small children play, to avoid close and prolonged contact with the spray residue.
Even more alarming are sprays containing a pyrethroid (pyrethrum) compound. The latter is derived from a plant and is therefore sold as ‘natural’, but pyrethroids are potentially toxic with prolonged exposure, and they quite often provoke allergic reactions too. They should definitely be avoided.
Sprays that inactivate allergen (rather than killing mites) sometimes have their uses. There are two kinds and both should work against a variety of allergens, not just dust mite. Polysaccharide sprays stick the allergen particles together, so that they don’t float about and get inhaled. Tannic acid sprays change the allergen chemically, making it non-allergenic. Because tannic acid is found in tea it is assumed to be harmless, but the sprays available vary a lot and often contain many impurities, so it is hard to be sure about their long-term safety. Don’t use these sprays on bedding.
Carpets and bedding covers with built-in pesticide are also on sale, but are probably best avoided.
does its job well – a lot of machines now claim to be ‘allergy’ vacuum cleaners but they are not all equally good. Very few have been adequately tested (see p. 255). Alternatively, cover the bed with a clean sheet and open the windows whenever you vacuum, leaving them open for half an hour afterwards. After closing the windows, allow the dust to settle for another half hour, then carefully remove the dust-cover from the bed.
For dusting, use a damp cloth and add a few drops of eucalyptus oil which deters mites. Alternatively, use a special anti-mite duster with an electrostatic charge that holds the dust.
Above all, keep the moisture levels in your house down. Ultimately, this is the key to eliminating dust mite. Look at p. 119 and check you are doing everything possible.
The bedroom in particular should be kept dry. Air your bedroom whenever it’s dry and sunny. Remove pot plants and fish tanks. Don’t dry clothes in the room and don’t shampoo the carpet. Avoid using Calor gas heaters, as these produce a lot of moisture. If your bedroom has an en suite shower, fit a powerful extractor fan, or open a window wide during and after showers – or just stop using this shower. En suite basins may also generate moist air.
Do you need to do more?
Give it some time before deciding if you have done enough. In one study, it took eight months for the full benefits of an anti-mite campaign to be seen.
If you are still not as much improved as you hoped, then you could try a more drastic mite-elimination programme.
Thoroughly clean the bedroom, getting rid of any dust along skirting boards or picture rails, on top of wardrobes or behind furniture. Remove anything stored under the bed, so that vacuuming is easier in future. During this cleaning operation, completely cover the bed.
Get rid of the bathroom carpet, if you have one. In the bedroom, either remove the carpet or buy a special anti-mite steam cleaner that kills mites in the carpet and inactivates the allergen. To work properly, the device must produce steam at a temperature above boiling point, by means of high pressure. Make sure you are buying the right kind of device.
If you take out the carpet, you will need to mop the floor, with a wet or oiled mop, several times a week, as the dust will quickly build up, and is easily made airborne from an uncarpeted floor. One of the advantages of carpet is that it ‘holds’ dust at floor level.
Wash the curtains, or dry-clean them, or replace them with blinds of a kind that can be easily wet-dusted. If you have bought an anti-mite steam cleaner for the carpet, use this on the curtains every 2-3 weeks.
Remove dirty clothes from the bedroom, clean out drawers and shelves, and dry them thoroughly. Only store freshly laundered clothes in the room.
Remove all upholstered items from the bedroom, such as padded headboards, cushions, armchairs, or stools with padded seats. Draught excluders, fabric lampshades and anything covered in velvet should also go.
A different approach
If you are even more allergic to housework than you are to dust mites, consider buying a really powerful dehumidifier, designed for killing mites. This makes the air too dry to breathe (its relative humidity or RH goes down to 25%), so you leave it on in the bedroom during the day, with the bedroom door closed. You must eliminate all sources of moisture that will counteract the dehumidifier, and have fairly tight seals around your windows and doors for it to work. In the evening, turn the dehumidifier off and leave the bedroom door open for an hour or so before going to bed.
Of course, all the allergen which was already there in the bed, carpet, curtains, clothes and soft toys will still be present. You need to either eliminate or inactivate this allergen using the methods described above. But once you have got your daily dehumidifier routine going, you do not need to rewash everything regularly because mites will be a thing of the past, so no new stocks of allergen will be produced.
The rest of the house
A completely mite-free house is hard to achieve, but if you are determined, you can come close. Everything so far described for the bedroom, such as reducing moisture in the air, and dealing with carpets and curtains, is applicable to the rest of the house.
The exception – and the toughest nut to crack – is the upholstered furniture in the living room. Fixed upholstery (i.e. everything other than removable cushions) is a safe haven for mites that is especially hard to deal with.
One option is to give all such furniture a specialist heat-treatment, if this is available locally (see p. 115). The mites inside will be killed, and the allergen inactivated. If you drastically reduce moisture levels at the same time – with a powerful dehumidifier used at night, perhaps – you should avoid serious reinfestation.
Alternatively, you could replace all your existing upholstered furniture with leather-covered or vinyl-covered furniture. Both are impenetrable to mites. Furniture made of wood or bamboo with loose cushions and no fixed upholstery can also work. Fit the cushions with tailor-made mite-proof covers (hard to get, but ask around) when new. Then put the ordinary covers on top, and wash these regularly.

FOOD SENSITIVITY IN ASTHMA, ECZEMA AND OTHER ALLERGIC DISEASES
In 1995, medical researchers in North Carolina, USA, asked over a hundred dermatologists how they treated atopic eczema. All used standard treatments such as moisturisers and steroid creams, but only 14% mentioned the possible role of food to the parents of children with eczema.
Between them, the dermatologists in this study treated about 17,000 children with atopic eczema per year. Using the most widely accepted estimates for food sensitivity in atopic eczema –38% of eczematous children are sensitive to food – one can calculate that there were over 5000 children in this study area who might perhaps have benefited from avoiding a problem food, but whose parents were never told about this treatment option.
North Carolina is by no means unique. The situation is much the same in other parts of the world, which adds up to millions of children and parents not even being told about a treatment that is frequently effective.
Other allergic diseases (see right) can also be triggered by food, although the percentage of patients affected is much lower than for atopic eczema. Here too, many doctors are unaware of (or sceptical about) the possible role of food.
These reactions are best described as ‘food sensitivity’. They cannot be called food allergy (see p. 62) if there are no symptoms in the mouth or gut and if skin-prick tests are negative – as is often the case. Negative skin tests suggest that the reaction is not IgEmediated (see box on p. 12).
However, in some children with atopic eczema. the skin-prick tests to culprit foods are positive. When these foods are eaten after a period of avoidance, such children sometimes suffer an
immediate reaction, with symptoms typical of true food allergy. For these individuals, their atopic eczema seems to be a symptom of IgE-mediated food allergy.
How can an atopic eczema reaction in response to food be IgE-mediated in one individual and not in another? Research is finally beginning to answer this question (see pp. 18-19).
The allergic conditions that may sometimes be induced, or simply aggravated, by a non-immediate reaction to food are:
• atopic eczema (atopic dermatitis)
• asthma
• perennial allergic rhinitis (constantly blocked or runny nose)
• chronic sinusitis
• secretory otitis media (’glue ear’).
In all of these conditions, many other causes exist. Except in the case of eczema, the other causes are far more likely than sensitivity to food. This fact will weigh heavily with your doctor, whose instinct, quite sensibly, is to look for likely causes first.
Taking asthma as an example, food sensitivity is relatively unusual as a primary cause, whereas allergy to airborne items. such as pollen or house-dust mite, is very common. Food probably affects only 8-10% of asthmatics overall, but is much more important for those with brittle asthma (the most severe and unstable form), affecting as many as 60% in a recent study.
The pollen connection
People who suffer from both birch-pollen allergy and atopic eczema may have worsening eczema when they eat certain fruits and vegetables, e.g. apples and carrots. These same foods cause Oral Allergy Syndrome (see box on p. 63) in some with birch-pollen hayfever, but they can aggravate eczema without causing Oral Allergy Syndrome.
Diagnosis
Consider other likely allergens first. Look at p. 28 for the airborne allergens that could play a part in perennial allergic rhinitis, chronic sinusitis, secretory otitis media (’glue ear’), and asthma. Only in the case of children with atopic eczema is food a prime suspect (between 38% and 69% of children with atopic eczema are affected by food), but even here there are a lot of other factors to consider (see pp. 43-4).
If you do decide to investigate the role of food, don’t abandon basic treatments in the meantime. By neglecting these. you could make the whole problem a great deal worse.
There are various clues that food is at fault:
• If you have other symptoms that suggest food intolerance (see p. 76). These problems often seem to go together with food-induced asthma or rhinitis.
• If you have noticed that a particular food makes your symptoms worse. Where there is intolerance to one food, there could well be intolerance to another, which you have not noticed.
• If you have exercise-induced asthma (see p. 41) and sometimes respond severely to exercise but sometimes have little or no reaction. Sensitivity to a food or foods may be instrumental in changing the response to exercise.
• If you have brittle asthma – but you must get your doctor’s consent for an elimination diet. Foods must be tested under medical supervision as severe life- threatening asthmatic reactions can occur on testing.
• If there are also digestive problems such as diarrhoea, vomiting or belching. This is a strong clue in the case of children with atopic eczema. Symptoms such as diarrhoea frequently precede atopic eczema, and it seems likely that a reaction to food in the gut increases the leakiness of the gut wall, allowing more food molecules through to the blood.
• If there is pronounced eczema around the mouth in children (but this can also be due to constant licking),
• For adults with atopic eczema, if there is a persistent rash on the hands, or the lips. Where there is a blistering rash on the hands that erupts at regular intervals, food is often the problem – or it may be metal contaminants of food such as nickel (see pp. 55-6). In general, food sensitivity is rarer among adults with atopic eczema than it is among children.
Skin-prick tests (see p. 91) for commonly eaten foods are worth
trying in all the diseases – if they give a positive result, they should
be noted, but if they give a negative one, they should be disre-
garded. The many alternative tests being marketed (see p. 93) are
highly inaccurate and unlikely to help.
Research from Tampere University Hospital in Finland suggests that babies are much more likely to give false-negative skin-prick tests for food than older children and adults with atopic eczema. The Finnish researchers found that 52% of babies with atopic eczema give a negative skin-prick test despite having a genuine reaction when tested by food challenge. In an attempt to tackle this problem, they have devised a patch test, similar to those used for contact dermatitis. The patch test, in which food is applied to intact skin and left there for two days, gives false negatives in only 39% of babies.
The best way to detect food-sensitive eczema, according to Dr Erika Isolauri. who heads the Finnish research team, is to use both tests, and take note of a positive reaction to either. This detects 80-90% of eczema-causing food reactions in infants.
Few other doctors are currently using patch tests for atopic eczema; because so much controversy surrounds this topic, and no standardised method has yet been devised. You may be lucky and find a specialist who does these tests.
To confirm the role of particular foods in atopic eczema, a food challenge test is essential, having first avoided the food carefully for two weeks. Great care is needed in testing (see p. 198).
If you cannot get suitable tests done. a simple elimination diet will be needed (see p. 198).
Treatment
There is a choice here, between avoiding the offending food, or eating normally and controlling the symptoms with drugs.
The difficulty comes when parents have to make this decision on behalf of their children. Unfortunately, there is insufficient evidence as regards the consequences of this decision. Treating food sensitivity can reduce the eczema symptoms substantially in the short term, but it does not necessarily improve the long-term prospects for the child. Orthodox doctors tend to think that eating a normal diet is much better for a child nutritionally and socially, and they have a point.
Doctors with a special interest in food sensitivity generally believe that treating the problem at source, rather than just suppressing the symptoms with drugs, must take the pressure off the child’s immune system, and give the child a better chance of growing out of sensitivity reactions in the long run.
The decision is yours – but it is vital that the diet is not more of an encumbrance than the disease itself, and that the child’s interests come first (see pp. 170-71). Whatever you do, don’t allow a child to become malnourished (see p. 198).

Atopic eczema
A Greek word meaning ‘to boil over’ or ‘to erupt’ is the source of the medical term ‘eczema’. It refers, of course, to the way in which the skin erupts into a rash, but it could equally well describe the eruption of controversy around this disease. No other allergic disease is quite such a cauldron of dissent - indeed, even the question of whether it is an allergic disease remains unresolved. These controversies directly affect the treatment of atopic eczema, so it is useful to understand them if you or your child have eczema.
The disagreement begins with the question of what causes atopic eczema.
Let’s start with the one point that everyone agrees on: dry skin plays a fundamental role. Those with atopic eczema have dry skin, not just in the eczematous areas, but in other parts as well, sometimes all over the body. The skin cells are less efficient than normal skin cells at retaining water.
Everyone would also agree that there is inflammation of the skin – a reaction that is produced by the immune system. But when it comes to the question of what starts off the inflammation there are huge differences of opinion among specialists treating atopic eczema – these specialists include dermatologists, allergists and paediatricians.
Since people with atopic eczema are atopic (allergy-prone), and most have
huge amounts of the allergy antibody, IgE, going round in their blood, it might
seem plausible that an allergic reaction to some external item kicks off the
inflammation. And when skin-prick tests (see p. 91) to common allergens such
as house-dust mite are tried, there are usually a large number of positive results.
But many of these turn out to be false positives – when tested more directly,
the allergen concerned does not actually play a part in causing the skin symptoms.
This has led some specialists working with eczema, mainly dermatologists, to
What the words mean
Eczema is not a disease in itself. The word refers to a certain type of reddish rash — a rash which can be caused in a variety of ways. The type of eczema that affects people of an allergic disposition (atopics), is called either atopic eczema or atopic dermatitis.
The word dermatitis just means inflammation of the skin. Most doctors consider it to be synonymous with eczema, but some give it a slightly broader meaning.
believe that allergic reactions play little part in either initiating or perpetuating atopic eczema. In their view, the basic cause of atopic eczema is dry skin and a generally overwrought immune system, not specific allergic reactions.
To some of these doctors, positive skin-prick tests are all false positives in atopic eczema – that is, irrelevant to the disease process. A positive skin-test result, in their opinion, simply indicates that the skin of atopic eczema sufferers is in a highly sensitive state, not that the allergen concerned plays any causative role.
Allergists tend to take a different view of this, as you might expect. And recent research shows that they are correct – allergens often do play a significant part in provoking atopic eczema.
Research using direct challenge tests (see p. 90) has identified some of the things that could provoke such sensitivity reactions:
• house-dust mites, pollen or moulds
• cats, dogs, rabbits and other furry pets
• cow’s milk or other food – a prime suspect in babies and young children (see p. 68). The response to food is usually delayed, occurring some hours after the item is consumed.
With mite, pollen and pet allergens, the eczema symptoms can be provoked either by allergens falling on the skin, or by direct contact (e.g. mite allergens in the bed, skin contact with pets, or lying on grass for those with grass-pollen allergy).
The rash tends to occur on skin not covered by clothes, as you would expect. But it can sometimes occur only on particular exposed areas – usually the most sensitive areas of skin. For example, there are people who react to house-dust mite but have eczema on the eyelids only.
Additionally, experiments show that even when an airborne allergen is only inhaled it can sometimes provoke eczema symptoms. The allergen probably reaches the skin in the bloodstream. (Alternatively, it might provoke an immune reaction in the airways which generates chemical messages of the kind that promote inflammation – these then reach the skin in the blood.) This means that the skin reaction could occur anywhere on the body, not just on exposed skin.
In the case of food, the molecules of food that cause the trouble are probably being absorbed from the stomach without being completely broken down. They then reach the skin via the blood to provoke a reaction there. (Or, again, it could be an inflammatory messenger chemical travelling from the gut to the skin in the blood.)
When food gets directly onto the skin – which it frequently does with small children, of course – it can provoke a reaction that way too. This may be a slow eczema-causing reaction, or a much faster reaction known as contact urticaria (see pp. 50-51). Reacting to food with contact urticaria is quite common in children with atopic eczema – but the same food doesn’t necessarily provoke atopic eczema when it is eaten. (However, eating these foods can sometimes trigger anaphylaxis – see pp. 58-9. They should therefore be treated with great caution.)
At the same time as all this research – which shows for sure that allergens play a part in atopic eczema – others have been asking what actually happens when skin reacts to an allergen. Their studies have turned the accepted understanding of allergies upside-down. They show that when something like egg or pollen provokes atopic eczema, what is occurring isn’t necessarily an allergic reaction of the usual sort, with IgE and mast cells (see
box on p.12). Instead, other immune cells are causing the trouble. Sometimes IgE is involved, but without mast cells. Sometimes neither is involved. These revolutionary discoveries are described in more detail on pp. 18-19. One interesting realisation from this research is that in different eczema sufferers, different immune reactions may be producing the rash – even if they are reacting to the same allergen! This helps to explain why the results of skin tests are so inconsistent and puzzling.
The wandering rash
For a baby with atopic eczema, the face, and especially the cheeks, are commonly affected, but there may be a rash all over the legs, the backs of the arms, and the back. As the months go by, the rash settles on the lower legs, and spreads to the fold of the elbow, and then the fold at the back of the knees — by about three years of age, this flexure eczema is the main problem for most children.
In adults, eczema is often found in quite restricted areas, such as the hands, scalp, lips, eyelids or chest. It may be located around the nipples — a sensitive spot where rubbing by clothing is enough to initiate a rash.
Atopic eczema is always in a process of change, and different parts of the body may display different stages of the rash:
• The rash is red and usually dry at first, and there may be not a great deal to see. In this early stage the visible signs may be minimal, while the itchiness can be colossal. Sometimes there is oozing of clear fluid.
• Occasionally the first phase is more marked, with dense patches of small red bumps or tiny blisters. On the hands, these may merge to form larger blisters.
• Infections tend to change the appearance of the rash (see p. 44).
• With time the skin becomes thicker, paler and scaly. It may form leathery patches (called lichenification), especially if there is habitual scratching or rubbing. This is chronic eczema.
• When the eczema clears, there may be an area of skin that is lighter in colour, or darker, than the surrounding skin.
The next step
Whatever causes atopic eczema, it provokes the most horrendous itching, as every eczema sufferer knows. The itch cries out to be scratched, and scratching is the major cause of the visible rash. If left untouched, the skin does not erupt into eczema, although it may well turn red, and there are still distinct changes in the skin that can be seen with a microscope.
Once eczema has erupted, the skin is no longer an intact protective layer that neatly separates ‘in-here’ from ‘out-there’. The skin becomes more permeable and loses its own natural moisture far more readily, so the dryness gets worse. At the same time allergens and irritants penetrate far more easily, causing yet more inflammation.
Something else compounds the damage: once atopic eczema is established, the immune system starts making IgE antibodies to the body’s own proteins, especially those found in skin cells. This helps explain why atopic eczema can become so severe and so entrenched.
Infections — another vicious circle
When eczema erupts and the skin barrier is breached, infections often become a problem. A regular source of trouble is the bacterium Staphylococcus aureus, a cause of the infection impetigo. This microbe invades eczematous skin far more readily than healthy skin, causing a prolific ooze with golden-yellow crusting.
Staphylococcus aureus produces a toxin known as a ’super-antigen’ which revs up the immune system to even more furious effort. This effort does not, unfortunately, oust the bacteria, but it does make the skin inflammation even worse. To add to their woes, many who are afflicted with atopic eczema start making IgE antibodies against Staphylococcus aureus toxins.
Infection with fungi (yeasts and moulds) is also a problem in atopic eczema (see p. 49), and there may be sensitivity reactions to these fungi.
The herpes virus, responsible for causing cold sores, can also invade eczematous skin, though this is much rarer. It worsens the eczema and produces fever and general weakness. There may also be flocks of small red bumps, each with a tiny dimple or blister at the centre. Any symptoms of this kind indicate that the patient needs urgent treatment.
Irritants and stress
People with atopic eczema are far more susceptible to everyday irritants such as wool and rough synthetic fabrics, soap, and traces of detergent left behind in clothes. Chlorinated water, either in swimming pools or from the tap, can also aggravate the skin, and even ‘hard’ water (found in areas with chalk or limestone bedrock) may be a factor.
Some air pollutants may play a part in atopic eczema. Researchers in Germany have found that children living close to busy trunk roads, or in homes with a gas cooker and no extraction hood (see pp. 128-9), were more likely to develop eczema. Formaldehyde fumes, often found in modern houses (see p. 129), are sometimes a factor when eczema affects the face and hands.

A blocked or runny nose in Allergy
THAT LASTS ALL YEAR
`Everyone has heard of hayfever, but it’s news to most people that you can have this sort of problem all year round,’ complains Elizabeth. ‘Before we got the treatment sorted out, Benny was “the kid with the constant cold”, and I did notice other mothers looking less than enchanted at the prospect of his coming over to play.’
Benny suffers from allergic reactions to house-dust mites and cats which cause hayfever-style symptoms (26) all year round. This condition doesn’t even have a common name – the medical one is perennial allergic rhinitis – yet it is one of the most common allergic diseases.
Any airborne allergen that is found in the air all year round can cause perennial allergic rhinitis:
• House-dust mite is the number one suspect in most parts of the world. Particles from other insects, such as midges and mosquitoes outdoors, and cockroaches, house flies, bloodworms (used for fish food) or carpet beetles indoors, can also cause nasal allergies.
• Mould spores can be the problem: they are found both indoors and out.
• In some regions, certain types of pollen are airborne all year round (27).
• All pets other than fish produce allergenic particles (even snakes).
• Allergens encountered at work (133) can also produce symptoms in the nose. This is a warning sign gn you should not ignore – it often means that occupational asthma is on its way (132).
Occasionally, the offending substance is being eaten not inhaled. This is less common, so you should investigate inhaled allergens first, before trying an elimination diet (29).
Skin-prick tests (91) will help to identify any airborne allergens that are responsible, but where food is the culprit, skin-prick tests are often negative (69)
Triad and NARES
Diagnosis of perennial allergic rhinitis is complicated by the fact that there are two other conditions – called triad and NARES – which produce similar symptoms and involve the immune system but are not, strictly speaking, allergies.
Triad is so called because it involves three distinct symptoms:
• perennial rhinitis
• polyps in the nose – little fleshy growths that can kill your sense of smell
• asthma.
People with triad tend to collect all three symptoms gradually, in no fixed order, over a period of years or even decades. Many are sensitive to aspirin and related drugs, and almost everyone with triad develops this sensitivity eventually.
Aspirin sensitivity can come on very suddenly and produces a reaction akin to anaphylaxis (101). This can be fatal, so it is probably best to avoid all aspirin-like drugs if you have triad, even though you have not reacted to aspirin in the past Aspirin-like drugs are found in painkillers, arthritis drugs and cold remedies – check with a pharmacist before you buy (151).
If you have asthma, think twice about operations on the nose to remove polyps – they can make the asthma much worse.
The initial letters of Non-Allergic Rhinitis with Eosinophilia have been stretched a bit to get NARES. (This is a medical joke –the Latin word Hares means nostrils.) The problem is caused by eosinophils (19), which flock into the nose and cause severe inflammation. Some people with NARES go on to develop triad.
Collateral damage
Having the nose swamped with mucus can lead to knock-on problems in the ears, sinuses and airways.
If the tube that leads from the ear to the nose (the Eustachian tube) becomes blocked, then fluid cannot drain away from the middle ear. This is called secretory otitis media, or glue ear - it dulls the hearing and causes an unpleasant ‘popping’ sensation. The ears may also feel blocked and itchy, but if children have had this problem since they were tiny they may not complain because they assume that’s just the way ears are supposed to feel. Deafness is often the first sign anyone notices.
Sinusitis is another possible complication, because fluid from the sinuses should also drain into the nasal cavity. With the ouflow blocked, mucus builds up in the sinuses and can become infected by bacteria (30).
Post-nasal drip can also occur with perennial allergic rhinitis. The over-abundant mucus runs down the back of the nose, into the throat and then the airways. This produces a persistent phlegmy cough, which may occasionally be mistaken for asthma.
When the rhinitis is treated effectively, all these problems should sort themselves out, although additional treatment is usually necessary in the case of persistent sinusitis (33).
Treatment
Where an allergen such as house-dust mite or mould spores has been identified as the source of the problem, eradicating it from your house (see Chapter 4) will make a huge difference, and may avoid the need for drugs. If the allergen is unavoidable, immunotherapy (see pp. 164-8) or some alternative form of desensitisation (see pp. 210-13) could be very helpful.
Where drugs are needed, nose drops are best. They get the drugs right to the target so doses are minimal, which means very few side effects. The drugs used are:
• cromoglycate to prevent the allergic reaction before it starts (148)
• antihistamines to block the allergic reaction before it produces inflammation (138)
• steroids to calm down inflammation (144). Steroid nose drops are also useful for NARES and triad. If you are taking steroid drops continuously, your doctor should check the membranes inside your nose every six months. Make sure you put the drops in correctly, especially if you have polyps (144).
If you suffer stinging, burning or dryness, it might be due to preservatives in the drops, not the drug itself (see box on p. 33), so talk to your doctor about a different formulation.
Don’t use over-the-counter decongestant drops: they do nothing to treat the allergy or inflammation, and are little more than a ‘chemical crowbar’ to open up the nose. Your nose gets addicted to them in a few days, and when you stop using them you get ‘rebound congestion’ - absolute and total blockage. It does wear off eventually, but is unpleasant meanwhile. If you are suffering this problem at this very moment, don’t put more decongestant drops in - your nose needs to go ‘cold turkey’ to recover, not have its addiction fed!
If none of the anti-allergy drugs work, but decongestant drops do, then you probably have a non-allergic disease called vasomotor rhinitis. The symptoms are very similar to allergic rhinitis, but without the sneezing and itching. See your doctor again, because there is an effective treatment that uses anticholinergic drugs (see box on p. 156). Acupuncture (see below) can also be helpful.
An elimination diet (194) will diagnose any food reactions. It works wonders for some people with severe and unexplained perennial rhinitis, Including people with such a flood of mucus that they can scarcely work or live normally. You should certainly give this diagnostic diet a try if there are clues that suggest food is the culprit (69) or if no airborne allergen can be identified. Yeast - found in bread, beer and B-vitamin tablets -is quite often the culprit in rhinitis, but it could be any food.
Acupuncture is worth trying, to reduce the blockage in the nose and stem the flow of mucus, because the autonomic nervous system (see box on p. 235) plays some part in the symptoms of allergic rhinitis (and is the sole cause of the symptoms for those with vasomotor rhinitis). For those with severe sinusitis, osteopathy can be good for draining mucus from the sinuses.
Very occasionally, psychological or emotional reactions play a part in perennial allergic rhinitis, with symptoms getting significantly worse during stressful events. One possible manifestation of this is post-coital rhinitis, where sex brings on rhinitis (and sometimes asthma as well). In such cases, psychotherapy should be considered. (But check you are not just allergic to the dust mites in your bed first…)
A nose by any other name…
Rhinitis means inflammation (-itis) of the nose (rhin-). The same Greek word gives us rhinoceros - ‘nose-horn’.