House dust mite allergy
The house dust mite is an arachnid about 0.3 mm in size and not visible to the naked eye. There are around 150 species of house dust mites in the world. One mite produces up to 40 faecal droppings a day. One teaspoonful of bedroom dust contains an average of nearly 1000 mites and 250,000 minute droppings.
Causes and triggers of house dust mite allergy
The house dust mite requires a warm, moist environment without light in order to live and reproduce. Our beds are ideal. The mite feeds on human and animal skin scales. The allergen is mainly contained in the mite’s faeces. The faeces contain allergy-triggering constituents which are spread in fine dust, are breathed in and can cause an allergic reaction.
Symptoms of house dust mite allergy
The symptoms of house dust mite allergy are: blocked nose, sneezing, runny nose, red eyes. They mainly occur in the mornings. Skin rashes and allergic asthma are possible delayed reactions.
Diagnosis and differential diagnosis
The diagnosis is based on thorough history-taking with the aid of skin and blood tests. Similar symptoms can occur in cases of pollen or mould allergy. Differences can mainly be identified in the place and time of onset of the symptoms. This is why it is worth observing the symptoms accurately.
Therapy and treatment
As a first step, mattress, pillows and duvet should be placed in mite-proof or anti-mite covers, sometimes known as encasings. At the same time, house dust should be minimised. If necessary, the symptoms can be treated with medication, for example antihistamines in the form of nasal sprays, eye drops and tablets. Desensitisation/specific immunotherapy (SIT) is recommended for house dust allergy.
Tips and tricks:
- Keep room temperature at 19–21°C and relative air humidity at a maximum of 50%.
- Remove dust from furniture with a damp cloth and regularly wet mop floors.
- Medical insurers are not obliged to meet the costs of anti-mite encasings. On a voluntary basis, some insurers will pay at least part of the costs if a medical certificate or prescription is presented.
Facts and figures
Higher than 1200 metres above sea level, mites stop reproducing. However, they can survive for up to 6 weeks in hotel beds (every guest introduces mites). A dry climate is basically hostile to mites. In Switzerland 5–8 % of children and adults are affected by allergy to house dust mite.
Editors: aha! Swiss Allergy Centre in co-operation with the Scientific Advisory Board.
aha! Swiss Allergy Centre helps
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