Dust Mites: Do They Bite and How Does Allergy Manifest

You wake up with a runny nose or sneezing, and red spots have appeared on your skin — and your first thought is: something bit you during the night. In fact, the reaction is mainly caused by mite allergens, not proven bites. Let's sort out where the myth about bites ends and allergy begins.

What dust mites are and where they live

House dust mites (Latin Dermatophagoides) are microscopic arachnids measuring from 0.1 to 0.5 mm. About 150 species of such mites have been found in house dust. They live in upholstered furniture, mattresses, carpets, bedspreads, and paper books, and they feed on dead human skin particles — a person sheds approximately 1.5 g of such particles daily. Their comfortable environment is an apartment with a temperature of 18–25 °C and humidity above 55 %. The mite life cycle is about 65–80 days, and the female lays approximately 60 eggs.

Do dust mites bite: what actually causes the reaction

The reaction is mainly caused by mite allergens, not proven bites: mite feces about 30 micrometers in diameter containing digestive enzymes (proteins Der f1 and Der p1) and antigen P1. These enzymes break down the skin cells that the mites feed on and trigger allergy in sensitive people. That is why "dust mite bites" is an inaccurate name for what is actually mite sensitization. There is also evidence that Dermatophagoides mites can parasitize humans, but the main mechanism of the reaction is allergic. Dermatophagoides mites play a leading role in the development of year-round allergic rhinitis.

What a dust mite rash looks like

The reaction more often manifests as raised rash (urticaria) or as itchy or reddened skin; on brown and black skin, redness is harder to notice. In people with atopic dermatitis, mite antigens can provoke flare-ups.

Symptoms of dust mite allergy

An allergic reaction may appear within minutes or several hours later. Typical symptoms of dust mite allergy:

• runny nose or sneezing
• red or watery eyes
• cough, wheezing, shortness of breath
• raised rash (urticaria), itching or redness of the skin
• pain or tenderness around the cheeks, eyes or forehead

In mite-related bronchial asthma, flare-ups occur in the spring-autumn period, especially at night. In 70 % of children with bronchial asthma, mite allergy is detected. Dust mite symptoms occur year-round, not only during the pollen season.

How allergy to house dust mites is diagnosed

Examination is prescribed by a doctor, if necessary an allergist. They may refer you for a skin prick test — when a small amount of allergen is applied to the skin and the reaction is observed — or for a blood test. Based on the results, the doctor draws up an allergy management plan.

When to see a doctor

See a doctor if you suspect an allergy in yourself or your child: they will decide which examinations are needed. Emergency help is needed for signs of a severe reaction — anaphylaxis.

By itself it is not a reason to call an ambulance; 103 or 112 — if your lips, mouth, throat or tongue suddenly swell, you are breathing very fast or gasping for air, you feel a tightness in your throat or cannot swallow, the skin, tongue or lips have turned blue, gray or pale, you have suddenly become very confused, drowsy or dizzy, a person has fainted and cannot be woken up, a child is lethargic and does not react as usual.

The material is for reference and does not replace a doctor's consultation — if in doubt, it is better to see an allergist than to guess from photos on the internet.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer