Allergies

Allergies are excessive responses of our immune system that cause symptoms of illness. There are many different types of allergy; however, these can be put down, generally speaking, to 4 different immunological responses, only 2 of which actually appear on the skin and mucous membranes, namely the so-called type I reaction (immediate-type reaction) and the type IV reaction (delayed-type reaction).
Immediate-type reactions occur within an extremely short time after contact with only the smallest amount of the allergen, The clinical symptoms are hay fever, allergic cold, allergic asthma, allergic weals and flares, and insect toxin reactions and food allergies, both of which may be accompanied by shock.

Type I reactions can be accompanied by relatively harmless, albeit unpleasant, symptoms such as classical hay fever, but also by life-threatening conditions such as allergic shock reactions. Also immediate-type I reactions to foodstuffs, e.g. the protein in nuts or fish, can trigger life-threatening shock responses.

Type IV or delayed-type reactions are allergic contact eczemas, i.e. allergic reactions caused by contact of the skin, or more rarely of the mucous membranes, with certain substances (contact allergens). The patients may suffer itching, redness, swelling, scaling, blistering and even chronic thickening of the skin. Typical examples of this form are nickel allergies (caused by “fashion jewellery”) or allergic reactions to hair colouring agents or the fluids used for permanent waves. In this case, the skin changes do not occur immediately after contact with the allergen but only a few days later, which can sometimes make it difficult to discover the cause. An allergic contact eczema usually needs a longish sensitisation period during which the excessive immune reaction gradually builds up. It is not uncommon for allergic responses to perfume agents or preservatives in cosmetics to occur only after use of the product for many years. The time needed for a potential allergen to trigger an allergic response varies strongly. There are substances with a very high allergenic potential, and others that cause allergies only after very long contact, and even then only in very few people. The development of contact eczema is fostered by pre-damaged skin, e.g. that is very dry through frequent contact with water.

To identify the causes of allergies, various test systems are used. In the case of allergic colds, droplets of highly purified allergens are applied to the skin of the forearm; the skin is then superficially punctured with a needle so that the allergen can penetrate the skin more easily. Following this prick test, an allergic response, if any, will develop after a waiting time of only 10 to 15 minutes in the form of an itching bump, similar to a mosquito bite. Another possibility is a RAST test, a special form of blood analysis, which allows IgE antibodies against certain allergens such as pollen, house dust mites or animal hairs, to be identified in the blood.

Type I allergies are a very common condition today. It is believed that about 15 % of the population are sensitised to some degree. In the case of severely allergic people, as few as 20 grains of rye pollen, for example, can already trigger an allergic reaction. A single ear of rye contains approx. 20 million grains of pollen.

Common inhalation allergens

Seasonal allergens: hazel, alder, birch, grasses, rye, mugwort
Perennial (year-round) allergens: house dust mites, mould, animal hairs or animal saliva.

Type IV reactions can be identified by epicutaneous testing (plaster test) on the skin of the back or the upper arms. As these are delayed-type reactions, the contact between the potential allergen and the skin must be maintained for a considerable period.

Samples of the suspected substances are applied using special test plasters, which have to be left in place for 48 hours. On removal of the plaster, any positive test response can then be seen, i.e. an eczema reaction with redness, scaling, swelling or blistering. As some allergens, especially metals, take even longer to cause a response, a second inspection must be carried out after 72 hours. Unlike type I allergies, there is no reliable routine blood test for identifying type IV reactions.

The number of occupational contact eczemas has risen sharply in recent years. In the industrialised countries, some 2 % to 9 % of the population are affected by them. Professions that are particularly frequently affected are the building trades, the healing professions, and people working in the wood processing and the metal, rubber and food industries. Among the healing professions, an increasing number of latex allergies can be observed.

Therapy

As with all allergic reactions, the most important thing for type I allergy sufferers is, if at all possible, to avoid contact with the allergen. In the case of allergies against animal hairs, for example, this can usually be achieved over time. Contact with house dust mites can be reduced by taking appropriate measures. Against grass or tree pollen, however, patients are virtually unable to protect themselves.

Patients with less severe symptoms such as blocked or runny noses, sneezing attacks, or red and watering eyes can be initially treated with antiallergic medication in the form of eye or nose drops and/or tablets (antihistamines). These drugs are very low in side-effects. As most antihistamines cannot penetrate the blood-brain barrier, they do not cause tiredness. In the case of more severe symptoms, this medication can be combined with local cortisone nasal sprays. In the case of very severe symptoms or patients whose symptoms become increasingly worse over the years, the best treatment is hyposensitisation. This is currently the only causal therapy that offers the chance of getting rid of the allergy. All the other therapies such as nasal sprays, tablets etc. only suppress the symptoms but do not cure the causes.

Hyposensitisation is a form of “inocculation therapy” with highly purified allergen extracts, usually performed over a period of 3 years. The allergen extracts are injected at regular intervals with a thin needle into the dermis of the upper arm. Apart from a slight local reaction in the form of swelling, redness and itching, there are usually no side-effects. Allergic shock reactions after hyposensitisation have today become extremely rare.
The success rate with hyposensitisation is about 80 % in the case of pollen allergies, and slightly lower in the case of patients with allergies to house dust mites.

Hyposensitisation is also recommended because some patients, after suffering hay fever for many years which has only been treated symptomatically, undergo a “change of storey”. This means that the allergic reaction no longer just affects the eyes and nose, but also the lungs, possibly resulting in bronchial asthma.
Patients with a year-round allergy are strongly recommend to buy an “allergy sufferer’s bed”. The traditional core spring mattress should be exchanged for a latex mattress. Pillows and duvets with synthetic filling should be used to avoid contact with the mites that live in feathers. The synthetic filling should be cleaned chemically once a year or, depending on the material, washed in the washing machine.

Tips for people with a pollen allergy
Ventilation: Only open windows in the evening or after heavy rain. Close the windows again by 3.00 a.m. at the latest as that is when the pollen starts flying again.

Clothing: Pollen collects in textiles and in the hair. Therefore do not dry clothes outside. Do not undress in the bedroom or hang clothes that have been worn during the day in the bedroom. Wash your hair before going to bed to remove pollen and prevent it getting on the pillow. Also clean glasses, if worn, several times a day to remove pollen.

Driving: Drive with the windows closed during the day, and allow fresh air to enter only through a pollen filter.

Holidays: Take your allergy into account when planning your holiday! Ideal holiday destinations for allergy sufferers are the seaside and the mountains.

Hyposensitisation is virtually vital for people with severe insect toxin allergies, which can often be accompanied by life-threatening shock reactions. Although such patients are provided with emergency medication, fatalities nevertheless repeatedly occur. Only successful hyposensitisation can give reliable protection against bee and wasp stings.

Allergic contact eczema, i.e. type IV reactions, can only be treated symptomatically. The allergic reaction will continue for life. Acute allergic contact eczemas are normally treated with cortisone ointments, which eliminate the reaction within days or possibly a few weeks. To prevent constant recurrence of the allergic reactions, with increasing deterioration and scatter reactions, it is essential to avoid all contact with the allergen throughout life. The more frequent the contact, the more severe the allergic reaction becomes. Ultimately, the allergy may spread beyond the points of direct contact with the allergen to the whole body (scatter reactions). If allergen contact is not interrupted, very severe reactions can occur over the whole body. These reactions can occasionally be seen in the case of nickel allergy sufferers who had repeated contact with the metal over a long period of time. As nickel also occurs in certain foodstuffs such as tea and chocolate, even drinking a single cup of tea can trigger a reaction over the whole body in people who are highly sensitised.