A house dust mite allergy is triggered by house dust mites and their faeces. House dust mites are among the most important allergy triggers.(1) A characteristic of a mite allergy is that it causes allergic symptoms all year round.
House dust mites occur almost everywhere where people live. They cannot be seen with the naked eye. They are small, eight-legged arachnids of 0.2-0.4 mm in size, living at temperatures of 15-32 degrees Celsius and need a high humidity of 70-80%. House dust mites are a natural part of the "home" ecosystem. Their occurrence has nothing to do with a lack of hygiene and they do not transmit diseases. The lifespan of these tiny creatures is between two and four months. During this time they produce 200 times their own weight of allergen-containing mite faeces.
In the dwelling we find mites everywhere, where they find the necessary humidity, warmth, darkness and food. Mites feed on skin flakes. An adult person loses about 1.5g of skin scales per day. About 100,000 mites can feed on this. Mites find ideal living conditions in bed. Mites and faeces accumulate mainly in the pillow, bedspread and mattress. But they also get into the house dust and are thus distributed on carpets, floors, curtains and sofas. Every time we move, the dust is stirred up. Vacuuming in particular increases the allergen load of the room air, as the excrement particles are so small that they are blown out again into the room through the exhaust air filter. Mites can hide particularly well in long pile carpets. These offer mites excellent protection and good chances of survival, as they can cling to the fibres and are thus hardly caught by the vacuum cleaner.(1)
With the beginning of warmer and humid weather in early summer, the mites begin to reproduce. The highest population number is reached in midsummer and the first months of autumn. In autumn, with the beginning of the heating period, most house dust mites die due to decreasing humidity. Nevertheless, it is at this time that the symptoms of a mite allergy climax. Now a maximum amount of mite excrement has accumulated, which disintegrates and is distributed with the dried mite particles through the heating air in the apartment. If these harmless substances are inhaled by a mite allergy sufferer or reach his mucous membranes, allergic symptoms can be triggered.