Macro shot of a house dust mite - House dust mite allergy - aha! Swiss Allergy Centre - Info on allergies - © Image: Sebastian Kaulitzki / Fotolia

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.

Contents overview:
Causes and triggers of house dust mite allergy
Symptoms of house dust mite allergy
Diagnosis and differential diagnosis
Therapy and treatment
Tips and tricks
Facts and figures
Supporting offers

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

When the allergens come into contact with the mucous membranes in the eyes, nose, mouth and throat, sufferers develop symptoms typical of an allergic cold (allergic rhinitis) or an allergic inflammation of the conjunctiva (allergic conjunctivitis): blocked or runny nose, sneezing, red, itchy eyes. If all of these symptoms are present, then the condition is also known as rhinoconjunctivitis. Often, the upper respiratory tract becomes chronically inflamed, primarily because house dust mites are present all year round.

The symptoms of house dust mite allergy typically occur in the morning and are more frequent in the cold months of the year.

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%.
  • When staying overnight in other accommodation, we recommend taking your own bed linen and the above anti-mite mattress covers with you.
  • Ideally, thoroughly air your home two to three times a day for 5 to 10 minutes each time.
  • It is advisable to wash nightwear and pyjamas at 60°C.
  • In general, try and buy only nightwear that is washable at 60°C.
  • Remove dust from furniture with a damp cloth and regularly wet mop floors.
  • Do not put pot and hydroponic plants in the bedroom and also avoid putting too many in living areas, as they increase room humidity.
  • Ideally, use sealed parquet or laminate flooring, cork tiles or flooring made of novilon, PVC etc.
  • 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.
  • You should therefore consider taking holidays in the mountains. Holidays in subtropical and tropical countries and on a farm are less advisable.

Facts and figures

Holidays at altitudes above approximately 1200 metres above sea level are advisable. However, mites can survive for up to 6 weeks in hotel beds (every guest introduces mites). A dry climate is basically hostile to mites. In Switzerland 6.5 % 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. For prevalence figures, see source references.

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