Allergy: what is a dust mite?
Mites belong to the arachnid family, like spiders and scorpions. These tiny organisms invisible to the naked eye (they measure approximately 0.3 mm in length, less than the thickness of a fingernail) feed on skin debris and proliferate in our homes: in one gram of dust, we can find up to 10,000 mites!
If there are more than 50,000 species of mites listed, the most widespread in Europe are Dermatophagoides pteronyssinus (DP), Dermatophagoides farinae (DF) and, more rarely, Euroglyphus maynei.
To know : in a house (even a clean one!) dust mites mainly develop in mattresses, rugs, upholstered furniture, carpets, soft toys and bedding (duvet, pillowcases, sheets, etc.) .
What attracts dust mites? What causes an allergy?
Certain conditions favor proliferation of mites :
- A room temperature above 20°C,
- A humidity level greater than 60%,
- A poorly ventilated bedroom,
- The presence of “dust nests” (thick carpet, curtains, large numbers of soft toys in the child’s bed).
Dust mite allergy is caused by inhaling fecal particles emitted by these tiny organisms. Concretely, in certain people, the immune system will react abnormally when an allergen emitted by a dust mite (there are at least 21 different ones) is found in a contact area: respiratory and ocular mucous membranes.
What are the reactions in someone allergic to dust mites?
Dust mite allergy can manifest itself differently depending on the patient: in some, symptoms will only appear in situations where they are exposed to high allergen concentrations – between spring and autumn, in cases work at home, in the event of a night spent in an old house, in a confined or rarely ventilated space, during a cleaning session, etc.
In others, the symptoms will appear regularly, even when the environment seems less loaded with allergens – the dust mite allergy can thus manifest itself permanently.
The main symptoms of dust mite allergy are allergic rhinitisL’allergic asthma and the allergic conjunctivitis.
Allergic rhinitis
Allergic rhinitis is caused by allergic inflammation of the upper airways (nose, nasopharynx and larynx), due to the inhalation of allergens.
The four main symptoms are runny nose (the fluid is clear: this is rhinorrea), itchy nose (pruritus), sneezing (often in bursts) and stuffy nose (obstruction). More rare, a loss of smell (anosmia) is sometimes present in children. Dust mite allergic rhinitis is often seen in the morning, upon waking up.
Allergic asthma
Allergic asthma is a inflammatory bronchial diseaselinked to the inhalation of allergens, particularly present on pillowcases and soft toys.
The asthma attack manifests itself – at the end of the night and upon waking – by difficulty breathing (dyspnea), wheezing, a feeling of chest tightness, sudden and recurring coughs, shortness of breath after exercise, and sometimes abnormal fatigue and/or paleness.
Allergic conjunctivitis
More rare, allergic conjunctivitis in the context of dust mite allergy is characterized by red, itchy and/or watery eyes, with swollen and/or stuck eyelids. Here again, allergic conjunctivitis due to dust mites is usually seen in the morning.
To know : in France, 20% to 30% of the population has a respiratory allergy and dust mites are the primary cause.
How to treat a dust mite allergy?
Firstly, the aim is to reduce the number of mites present in the environment.
What to do against mites? Eviction measures
These very simple preventative measures can considerably improve the quality of life of patients allergic to dust mites :
- Vacuum 1-2 times a week throughout the house, paying particular attention to carpets and rugs.
- Ventilate the sleeping area twice a day all year round (at least twice for 10 minutes). In winter, keep the temperature between 18°C and 20°C. If you have a humidifier, set it to no more than 50%.
- Avoid plants in the bedroom.
- Keep one or two washable stuffed animals in the child’s bed, no more.
- Put an anti-mite cover on the mattress.
- Wash bedding (sheets, duvet covers, pillowcases, etc.) once a week at 60°C,
- Wash pillows and duvets/blankets/plaids… every 6 to 8 weeks at 60°C.
To know : “anti-mite solutions” (sprays with acaricidal essential oils, etc.) sold commercially can also be effective in reducing allergy symptoms. To test !
What medications for this allergy?
The medical treatment of dust mite allergic rhinitis is based on local antihistamine and/or corticosteroid treatments. The goal: to quickly stop rhinorrhea, sneezing and nasal obstruction. The latest generation molecules have almost no side effects; older medications could cause drowsiness.
In the event of allergic asthma, regular monitoring is essential! Drug treatment includes bronchodilators (β2-mimetics) and inhaled corticosteroids. Finally, in the event of allergic conjunctivitis, eye drops (antihistamines, anti-inflammatories, etc.) may be prescribed.
Desensitization as a treatment for severe allergies
Patients suffering from a severe dust mite allergy, which resists avoidance measures and drug treatments, may benefit from immunotherapy (also called “desensitization”) prescribed by a doctor specializing in allergology.
Concretely, this treatment consists of injecting the patient with progressive doses of allergens subcutaneously – first every week then monthly for 3 to 5 years.
Source :
French Journal of Allergology 53 (2013)
Immunology and Allergy Department – Vaud university hospital center (CHUV)
Read also :
⋙ Mite allergens in breast milk
⋙ Mites: advice from the allergist to get rid of them
⋙ Mites: these little creatures that sleep with us (video)