Generality
Dust mite allergy is a hyper-reaction of the immune system caused by small arthropods commonly found in the domestic environment.
Mite allergy is one of the most common allergic forms. Mites are responsible for about 75% of respiratory allergies and can cause discomfort at any time of the year.
Symptoms
The manifestation of allergy to dust mites may vary: it may be mild or severe.
The allergic reaction, caused by the inhalation of the remains of dead mites and their defecations, can occur with symptoms mainly respiratory (rhinitis and / or asthma). Sometimes, redness / swelling of the eyes, tearing, light discomfort, a sense of general malaise, weakness and states of anxiety also appear. Allergens cause the release of histamine which causes nasal congestion, swelling and irritation of the upper respiratory tract.
Symptoms of dust mite allergy may appear simultaneously or in later stages:
- Symptoms caused by inflammation of the nasal passages:
- rhinitis: nasal obstruction, sneezing (in rapid succession), runny nose (rhinorrhea);
- conjunctivitis: tearing, redness, itching, swelling and eye irritation;
- itchy nose, palate or throat.
- Symptoms associated with asthma and breathing difficulties:
- chest tightness;
- wheezing (whistle heard during exhalation);
- dry cough;
- difficulty breathing (especially during sleep or during physical exertion);
- sleep disorders due to shortness of breath, coughing or wheezing.
In some cases, allergy to mites can cause:
- atopic eczema, redness, rash;
- skin redness and itching in the face and scalp.
Sleep disturbances and the state of permanent fatigue caused by allergy to mites can negatively affect daily school and professional activities, adversely affecting quality of life.
How to distinguish dust mite allergy from a normal cold?
Some signs and symptoms of allergy are quite similar to those of a common cold. Winter is a time of year when the appearance of symptoms can cause confusion in the allergic subject. Some simple factors that help distinguish allergic rhinitis from a viral airway disease are:
- prolonged persistence of symptoms: a cold does not last several weeks;
- the symptoms become more evident in particular situations (example: stay in rooms that are not properly ventilated).
The suspicion that an allergic reaction is taking place can be confirmed by medical examination, performing skin tests and blood tests.
What can make the symptoms worse?
- Poor ventilation of the rooms;
- High humidity;
- High temperatures (above 20-21 ° C);
- Air pollution (tobacco smoke or gas produced by the car);
- All the operations that allow the dry stools of dust mites to disperse in the air, exposing the allergic subject the most: walking on a carpet, sitting on a chair or shaking the bed linen.
Cross-allergies
A mite allergic patient may also have cross reactivity with certain foods.
Mite allergy can cause a reaction with:
- Crustaceans, mussels and molluscs (shrimps, lobster ...);
- Land and sea snail;
- Tyrophagus putrescentiae (food mite, you can find allergens in wheat, flour, ham, cheese and mushroom cultivation);
- Cockroach.
Diagnosis
The suspicion of dust mite allergy can be confirmed based on symptoms and identification of the allergen involved. To define the diagnosis, a series of checks must be carried out:
- History : the doctor can reconstruct the patient's personal and family medical history, as well as formulate specific questions on symptoms;
- Specialist allergy examination : to assess any clinical signs present;
- Skin tests: first choice tests for allergy diagnosis. In particular, the Prick test identifies most allergens. It consists of applying a drop of the allergen extract, usually on the forearm, and then puncturing the area with a special needle. If the person is allergic, a wheal occurs within a short time (the skin appears to be detected, reddened and itching is felt).
- Blood test : the RAST test (or specific IgE assay) highlights the reaction of antibodies directed towards a particular substance and provides an indication of the degree of sensitivity of the patient with respect to exposure to the allergen. It is used to confirm the Prick test result.
Treatment
"Symptomatic" treatments and specific immunotherapy
The first useful treatment to control allergic reactions caused by dust mites is to avoid or minimize exposure to the allergen as much as possible. However, it is impossible to completely eliminate dust mites from your environment.
To control the symptoms of allergy to mites you can instead rely on different drugs such as:
- Antihistamines : counteract the formation of histamine produced by the immune system, an active substance during the allergic reaction. These drugs help relieve symptoms such as itching, sneezing and a runny nose.
- Local corticosteroids (nasal sprays): may reduce the symptoms associated with inflammation.
- Decongestants : can be used temporarily to provide rapid relief of nasal congestion.
- Antileukotrienes (in case of asthma): they block the action of some chemicals of the immune system. These medications, taken orally, alleviate allergy symptoms such as nasal congestion.
- Cromones : prevent the release of histamine and other chemicals from the immune system.
The results of the diagnosis can favor the development of a desensitization treatment against the allergen (the so-called " vaccine "). This protocol is developed in two phases. At first, minimal and increasing doses of allergen are given (sublingually or subcutaneously). The objective of this first phase is to rehabilitate the immune system to remain insensitive to exposure to dust mites (lasting 3-6 months). The subsequent maintenance phase involves taking a daily dose of preparation, for at least 3-5 consecutive years.
The desensitization treatment has the potential to significantly reduce allergy to dust mites, until it disappears , but must be followed with extreme constancy.
