The house mite (Dermatophagoides pteronyssinus) belongs to the family of arachnids. These creatures are microscopically small (about one-third of a millimetre) and invisible to the naked eye. The term for the most important dust mites in our latitudes is “Dermatophagoides”, which means “skin eater”. In fact, the mites feed mainly on human and animal dander, but also on natural fibres, feathers, wool, and food scraps. Associated allergies aside, dust mites are harmless creatures. The substances responsible for triggering the allergy are mainly contained in the excretions of the mite. In a gram of house dust from upholstery or mattress are, depending on the mite count, about 10,000 such faeces. These disintegrate, get picked up along with the house dust, are inhaled, and lead to allergy symptoms of the mucous membranes of the respiratory tract in people with a dust allergy. In addition, intensive contact (for example, in bed) can lead to allergic rashes (urticaria, hives). The diagnosis of dust mite allergy relies on a corresponding medical history and further investigative steps, such as a skin test and laboratory examination. Studies have shown that the allergen concentration, which causes the complaints of allergy sufferers, takes place mainly during sleep. High humidity and room temperatures of over 22 degrees create optimal living conditions for mites. During sleep, the temperature in bed increases to 25-30 degrees and our body releases moisture – the ideal conditions for the dust mite to feed and to multiply. Therefore, all efforts to reduce allergen exposure should focus on the bed. The highest mite concentrations are found in bedrooms: specifically in comforters, pillows, and mattresses. Upholstered furniture is also a preferred habitat for mites. Carpets and rugs are also populated, but they are only of secondary interest. The highest levels of mites are to be expected in autumn (beginning of the heating season) and in spring. Despite the greatest cleanliness, mites from textile furnishings cannot be completely eliminated with normal methods once they have colonized them.
- Avoid carpets and indoor plants in the bedroom.
- Do not keep dust collectors such as heavy curtains, throws, and throw pillows.
- Soft toys often cause problems for children, so the number of stuffed animals in bed should be reduced. These should also be stored regularly in the freezer for 24 hours and then cleaned precisely with the vacuum cleaner. Alternative: tumble dry for 1 hour at 60 degrees.
- Keep the temperature in the bedroom at approx. 18° - 20°C and the humidity below 50%.
- Very old mattresses (> 10 years old) should be replaced.
- Replace upholstered furniture with wood or plastic furniture, with leather upholstery in preference to fabric.
- If this is not possible, regularly use special cleaning sprays (acaricides) to kill the mites.
- Vacuum cleaners should have special microfilters (HEPA filters) so as not to stir up the allergens.
- Dust mite covers are an effective mite reduction measure; however, these are not cheap (the fitting of a double bed with mattress, blanket, and pillow covers can cost several hundred euros). It is advisable not to save here, because cheap coverings are usually ineffective.
If you cannot buy mite-proof covers, then
- Use only duvets and pillows that are washable at 60°C or higher.
- Wash the sheets weekly if possible, and duvets and pillows once a month.
- Alternatively, you can treat blankets and pillows in the dryer for 1 hour at 60°C even when dry.
In any case, the remedial measures summarised here bring a clear improvement, and in some cases a complete normalisation of one’s state of health can be achieved. If these measures do not succeed within about six months, a medical check-up is required to discuss further therapeutic approaches (medication, vaccine treatment).