Why does a child have an allergy to dust mites? - briefly
Dust mite allergy occurs when a child's immune system mistakenly recognizes proteins in mite feces or body fragments as threats, leading to IgE‑mediated inflammation of the respiratory tract and skin. Genetic predisposition and early, frequent exposure heighten the risk of this hypersensitivity.
Why does a child have an allergy to dust mites? - in detail
Dust‑mite allergy in children arises when the immune system mistakenly identifies proteins from the mites as harmful invaders. The body produces immunoglobulin E (IgE) antibodies that bind to these proteins, triggering the release of histamine and other mediators that cause allergic symptoms.
The sensitisation process involves repeated inhalation of mite allergens such as Der p 1 and Der f 1. Upon first exposure, antigen‑presenting cells present the proteins to T‑helper 2 cells, which stimulate B‑cells to generate specific IgE. Subsequent contacts cause cross‑linking of IgE on mast cells, leading to rapid degranulation.
Factors that increase the likelihood of developing this hypersensitivity include:
- Family history of atopy (asthma, allergic rhinitis, eczema)
- Early and prolonged indoor exposure, especially in humid environments where mite populations thrive
- Presence of carpeting, upholstered furniture, or bedding that retain dust
- Inadequate ventilation and high indoor humidity (>50 %)
Typical clinical manifestations are:
- Nasal congestion, sneezing, itchy eyes (allergic rhinitis)
- Wheezing, coughing, shortness of breath (allergic asthma)
- Itchy, inflamed skin lesions (atopic dermatitis)
Diagnosis relies on objective testing:
- Skin‑prick test with standardized dust‑mite extracts – a wheal diameter ≥3 mm indicates sensitisation.
- Serum measurement of dust‑mite‑specific IgE – quantitative values guide severity assessment.
Management strategies focus on reducing exposure and controlling immune response:
- Encase mattresses and pillows in allergen‑impermeable covers; wash bedding weekly at ≥60 °C.
- Maintain indoor humidity below 50 % using dehumidifiers; vacuum with HEPA‑filter devices regularly.
- Remove carpets or replace with hard flooring; clean upholstered furniture with steam.
- Pharmacologic therapy: intranasal corticosteroids for rhinitis, inhaled corticosteroids or bronchodilators for asthma, topical steroids for dermatitis.
- Allergen‑specific immunotherapy (subcutaneous or sublingual) for children with persistent symptoms despite environmental control.
Effective control requires a combination of environmental measures, targeted medication, and, when appropriate, immunotherapy to modify the underlying allergic response.