House dust mite allergy T78.4

Type I allergy to the components in house dust. The most important allergens are the house dust mite (above all Dermatophagoides pteronyssinus and its main allergens Der p1, Der p2, Der p 23) and above all its excretion products, as well as feathers, animal hair and moulds. S.a. Papain.

Remark: The recently discovered allergen Der p23 belongs like Der p1 and Der p2 to the main allergens of Dermatophagoides pteronyssinus. S.a. mite allergens

Medical history; prick test (sensitivity > 90% and specificity > 80% for mite asthma compared to specific bronchial provocation - see also house dust mite allergens); provocation test (see nasal provocation test, methacholine provocation test), intradermal test, RAST, atopy patch test.

Determination of house dust mite load, detection of house dust mites or excrement using the Acarex test (1 g of house dust can contain 500-10,000 mites).

There is no causal therapy.

The main therapy is to reduce the house dust mite load, especially in areas where the patient frequently spends time. Sanitation and hygiene is particularly important where the mite concentrations are high (e.g. mattresses, pillows).

Bed accessories: Foam mattresses do not wick away moisture well. This encourages mold growth. Horsehair and kapok mattresses, sheep's wool and camel hair comforters, down and feather comforters should be eliminated. Prophylactic use of mite and dandruff-impermeable but air-permeable covers (Allergocover from Allergopharma; Curaderm Protection from Lohmann; see below. Encasing).

Please note! Mattress covers should be impermeable to mites and dandruff, but permeable to air!

Miticides: Benzyl benzoate (e.g. Acarosan foam, moisturizing powder, spray solution) or disinfectants based on carboxylic acid esters. Used as a foam spray for upholstered furniture and mattresses and as a moist powder for large surfaces such as carpets. They are available in pharmacies. The disinfecting effect is sufficient for almost 1 year. In the case of mattresses, repeated applications of Acarosan are necessary because mattresses are contaminated down to the deepest layers. It is advisable to get rid of old mattresses and disinfect new ones (see below) from the outset. Acarosan is non-irritating to the skin and mucous membranes.

Bedroom: Regular cleaning of the sleeping area (people spend about 1/3 of their lives in the bedroom). Wipe the floor with a damp cloth, do not use the bedroom as a living room during the day, no combing or personal hygiene in the bedroom (shedding). Blankets and pillows should be washed thoroughly twice a year with water and detergent. Dry cleaning is not sufficient to remove dander. Mattresses, all comforters, molleton sheets, pillows and sheets should be aired daily, outdoors in dry weather. Mattresses and pillows should also be vacuumed daily if possible, but at least once a month. No flowers in the bedrooms. Keep doors closed if possible.

Living room: Do not remove dust with a cloth (which stirs up dust), but with a vacuum cleaner. No carpets. If carpets are present, they should be vacuumed frequently. Use vacuum cleaners with fine dust filters and allergy filters.

The installation of an air filter device that removes dust from the air by ionization using high voltages has also proved effective. Such devices are suitable for pollen allergy sufferers and are offered by companies such as Braun, Miele, Honywell and Venta.

Bookshelves should be dusted with a damp cloth, preferably glazed. Carpet beating, making beds, handling dusty cloths, brushing or sweeping as well as vacuuming must not be carried out by allergy sufferers themselves, not even in their presence! Noticeable success in the renovation of the apartment can only be expected after weeks.

Walls should be painted with washable paint. Blinds or roller blinds instead of fabric curtains.

Choose smooth-surfaced furniture. No ornate, dust-carrying furniture, especially no plush furniture, armchairs, blankets, mattresses, head and couch cushions. Upholstered furniture should be fitted with plastic covers and smooth covers, e.g. leather. Metal furniture made of chrome steel, plastic seat parts and polyethylene foam with smooth, impermeable covers are recommended.

Lifestyle: Pets attract moisture and dirt, and also shed hair, feathers and dander. This encourages both mite growth and mold growth. With prolonged, intimate contact, there is always the additional risk of sensitization, the development of an allergy to the animal hair itself. Bird nests, dog and cat baskets, hamster and guinea pig cages can be assumed to be particularly rich in mites. Patients should not clean such places themselves (the ideal situation is, of course, a pet-free home).

Climate: Humidity is not only conducive to the growth of dust mites, but also of mold. It is important to keep the home dry. It makes sense to purchase a hygrometer and thermometer. The room air should be kept below 60% humidity and around 16-20 °C. Underfloor heating is the most suitable form of heating, followed by central heating with radiators under the windows. Individual stoves and fireplaces are less advantageous because they create cold and therefore damp areas in the room. To maintain a constant bedroom temperature, it is useful to have continuous heating during the day and night. Air conditioning systems are often breeding grounds for mold. Air conditioning filters need to be cleaned frequently.

When building a house, the first thing to look out for is dryness. Porous, air-permeable bricks are most favorable. Concrete is never completely dry. Wood absorbs moisture and should therefore be varnished. A basement is always useful. Effective drainage at the foundation wall and good insulation are recommended. In damp old buildings, these measures should be carried out retrospectively. Place the bedroom in a dry, well-sunlit room on a higher floor, away from the kitchen and bathroom, and never on the first floor without a basement.

Low-allergen environments such as the North Sea, desert climates and high mountains (Alps) have proven to be ideal for vacations.

In principle, the complete elimination of the causative allergen is the most efficient form of treatment.

Specific immunotherapies (SCID) now show clinically acceptable response rates and are recommended for asthmatic and rhinitis symptoms. Corresponding studies have led to the approval of allergen extracts (Depigoid [contains trees/grains/grasses/herbs/mite allergen]; Depigoid-Mite-Mix [contains equal parts D. pteronyssimus and D. farinae]; Depigoid D. pteronyssinus [contains chemically modified allergen extracts from Dermatophagoides pteronyssinus]) for long-term therapy.

Alternative - SLIT tablet: In a larger multicenter, ramdomized, placebo-controlled, double-blind study, the effect of SLIT was demonstrated (500IR or 300IR/day p.o. - note IR=Index of Reactivity). The positive effect of hyposensitization was maintained during the one-year observation period.

The preparation ^Acarizax® is approved for the indication "allergic rhinitis".

Since July 9, 2021, the sublingual preparation ^Orylmyte® (from 12 years of age) has also been available on prescription. Both preparations show a robust immune response to all relevant major allergens and therefore increase the likelihood of successful hyposensitization.

Allergic bronchial asthma is not a contraindication.

Dust mite allergy sufferers seem to benefit from SLIT. Retrospectively, a clinical improvement for 2-3 years after the end of SLIT could be recorded in a study with 53 test persons. An influence of SLIT on bronchial hyperreactivity or one-second exhalation capacity was not found.

Caution! Cross-reactions in clinically manifest house dust mite allergy and food allergy (see also mite crustacean mollusc syndrome) should be noted! These are based on a high homology of tropomyosin of mites, crustaceans and molluscs (see also house dust mite allergy).

A clinically relevant sensitization to house dust mites has a significantly increased risk of developing bronchial asthma compared to a pollen allergy.

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