An allergy to dust mites is an oversensitivity of the body to the excretions of the super-small arachnids. It is not the mites themselves that are responsible for the symptoms: Their droppings trigger symptoms such as sneezing, itchy eyes and ears, asthma and skin rashes when those affected breathe them in or come into contact with them.
House Dust Allergy Causes And Risk Factors
People with a house dust mite allergy are hypersensitive to certain proteins in house dust mite faeces. The small arachnids themselves are harmless. They don't sting or bite, they don't suck blood, and they don't transmit disease. They are too small to be visible to the naked eye. Their favorite food is human dander. That is why they mainly stay in beds, i.e. in mattresses, pillows and duvets. They also like to be in upholstered furniture and carpets. Dust mites feel most comfortable at temperatures above 25 °C and humidity between 65 and 80%.
The symptoms often peak in late autumn, when the heating season begins. The reason for this is that the humidity in the rooms drops. The majority of the mites die off, and more allergy-causing substances are released in the process. At the same time, the rooms in many households are only slightly ventilated in winter. The allergens therefore remain in the home for a long time.
Dust mite allergies have increased in recent years. The reason may lie in the structurally more effective insulation of apartments in order to save energy. At the same time, this increases the humidity in the rooms. If there is not enough ventilation, the house dust mites will be happy.
Risk factors
Genetics often determine which people develop allergies and which do not. If one parent has allergies, the children have a 30% risk of also developing allergies. If both parents are plagued by allergies, the risk increases to 50 to 70% that the offspring will also become ill. The symptoms are not limited to allergies, because the house dust mite allergy is one of the so-called atopic diseases.
Atopy includes allergic rhinitis (e.g. in house dust mite allergy, hay fever), conjunctivitis, neurodermatitis (atopic dermatitis) and asthma. That is why many people affected by allergies suffer from all diseases of the atopic type.
House Dust Allergy Symptoms
Do you have sneezing attacks when you wake up in the morning?
Do you often get itchy nose, mouth and throat in autumn and at the beginning of the heating period?
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| House dust allergy symptoms |
These symptoms are typical when house dust mites are responsible for an allergic runny nose (allergic rhinitis). The symptoms tend to appear in the morning after getting up and become worse in autumn and at the beginning of the heating season. Other symptoms include a runny nose, stuffy nose and itchy ears. In addition, the eyes are usually itchy and watery, they are red and sensitive to light, and even the eyelids can be swollen (allergic conjunctivitis, conjunctivitis). When symptoms in the nose and eyes occur at the same time, doctors speak of rhinoconjunctivitis.
Floor change
If those affected ignore their chronic cold, there is not only the danger that the immune system will react allergically to more and more substances. If symptoms such as coughing, wheezing, rattling breath appear, possibly combined with shortness of breath, allergic asthma may have developed. Then the allergy has migrated from the upper respiratory tract, such as the nose, down into the lungs. Doctors call this phenomenon floor change. Changing floors can possibly be avoided if allergic colds are treated in good time.
Symptoms in detail:
- Nose: Persistent runny nose and sneezing fits, itching and swelling of the nasal mucosa
- Eyes: itching and swollen, watery, red conjunctiva, swollen eyelids
- Ears: itching
- Throat and throat: itching and sore throat
- Lungs: asthmatic reaction such as coughing, wheezing, shortness of breath
- Skin: itching, rash and hives, eczema can worsen in people with neurodermatitis
Many of the symptoms are similar to those of the common cold, but there are differences. Colds usually announce themselves with a headache or scratchy throat, an allergy begins suddenly with sneezing attacks. The itching in the nose, eyes, mouth is often absent with a cold. In addition, the nasal secretion is very viscous in the case of an infection, and thin in the case of allergies.
Differentiation from other allergies
All substances inhaled that cause allergies (technical term: allergens) trigger similar symptoms, one speaks of inhalation allergies. It is therefore not always easy to differentiate between hypersensitivities to pollen, house dust mites, animal dander and mold.
While hay fever usually occurs when it is blooming outside and the pollen is flying, a house dust allergy generally affects those affected all year round and when staying in closed rooms. Allergy to mold can also occur all year round. Mold allergies primarily affect those affected in places where mold is found, such as in basements or on compost heaps.
Animal allergies also occur all year round, but usually after or during contact with animals that have hair or feathers. Skin scales, saliva, sebum, urine or faeces are the protein-containing triggers of hypersensitivity.
House dust allergy in children
An intolerance to mite faeces can develop very early in childhood. However, because the symptoms in children are similar to those of other diseases such as respiratory infections or are masked by them, many parents do not think of an allergy at first. If a child from around the age of two often suffers from colds or other infections of the respiratory tract, it could be possible that allergies are behind it. They make the mucous membranes more susceptible to infection, so it is advisable to have the child tested for various allergens.
What happens in the body when you are allergic to house dust mites?
The human immune system has the important task of protecting the body from attackers. It starts checking immediately when the body absorbs a foreign substance through the nose, skin or gastrointestinal tract. Is the foreign substance harmless or dangerous?
If the immune system detects a threat, such as bacteria and viruses, it is its job to start a defense reaction. In people with allergies, however, the immune system cannot always differentiate between harmful and harmless environmental substances. It can accidentally classify harmless substances like house dust mites as dangerous. When they first meet, it forms antibodies (technical term: class E immunoglobulins, IgE). This phase is called sensitization because allergic symptoms do not yet appear.
The actual defense work only begins when there is renewed contact with the alleged attacker. The immune system sends out the precautionary IgE antibodies to stimulate so-called mast cells to act. They release inflammatory messengers such as histamine. Within minutes, but after two hours at the latest, histamine causes the typical symptoms such as sneezing attacks and red eyes. Thus, the house dust allergy belongs to the allergic immediate type (type 1 reaction).
Cross allergies
Many house dust allergy patients also suffer from food allergies. This is due to cross-reactions between the mite excretions and certain foods, because both have allergens that are the same or similar. In the case of house dust allergies, cross allergies with crustaceans such as crabs, crabs and lobsters are known, and molluscs such as mussels and snails also seem to be poorly tolerated.
If those affected eat these foods, red and itchy spots form. Wheals can also develop on different parts of the body. The face, lips, and mouth and throat may swell. Mouth and tongue feel furry, throat starts to itch. The usual symptoms of the eyes and nose can also occur. In the worst case, the circulation crashes and a cold sweat breaks out. Then it is possibly an allergic (anaphylactic) shock.
Immediately to the doctor
Allergic (anaphylactic) shock can be life-threatening. He makes himself felt very quickly. The typical signs include: formation of wheals, the throat swells up, tingling in the hands and feet - the symptoms of an allergic shock are varied. Important: Call an ambulance immediately at the first sign of shock.
House Dust Allergy Treatment
House dust allergy specialists are allergists. They will ask under what circumstances the symptoms occur and how long they last. Is there a specific time when symptoms appear, e.g. more likely in the morning or evening? At home or in nature? Do they show up all year round or are they seasonal, meaning only in spring, summer or fall? If those affected have kept a diary of when they experience which symptoms, the entries can help the doctor with the diagnosis.
Once the preliminary talk (anamnesis) is over, various tests can unmask the triggers:
- Prick test: Various allergens are dripped onto the forearm. The skin below the drops is then superficially scratched or punctured with a fine lancet or needle, which is generally painless. If itchy wheals and redness form in certain marked areas, the allergist can see which sensitizations have taken place.
- Blood test: Blood tests provide information about the presence of class E antibodies (immunoglobulin E, IgE). The total amount of IgE antibodies (RIST test) can be determined. Since the total amount of IgE antibodies is not only increased in allergies but also in other diseases, this value only serves as a guide. In a second blood test (RAST test), the blood can be examined for specific antibodies that have been formed against the proteins of the house dust mite.
- Provocation test: If the diagnosis is difficult, there is the option of carrying out a provocation test. The doctor tries to provoke an allergic reaction under supervision in a practice or clinic. The allergen is dropped onto the nasal mucosa, for example. However, provocation tests are rarely carried out today because it is not possible to estimate how strong the allergic reaction will be.
Therapy
If house dust mites are responsible for the symptoms, there are several different types of therapy: The most important treatment method is to reduce the trigger, i.e. the mites. This includes renovating the living space with a whole range of measures that can be found under the heading "Prevention".
Acute symptoms can be relieved with medication. Specific immunotherapy, also known as hyposensitization, addresses the cause. In addition to conventional medicine, there are alternative healing methods.
Medical therapy
Antihistamine eye drops and nasal sprays can be used for acute symptom relief. With other active ingredients (e.g. with mast cell stabilizers), sprays and drops are also effective preventively. Antihistamines in pill form combat symptoms throughout the body via the bloodstream. Therefore, they not only help with allergic rhinitis, but also alleviate symptoms of food allergies. In the case of allergic asthma or if these active ingredients are not sufficient, doctors resort to glucocorticoids (e.g. cortisone).
The medications in detail:
- Antihistamines (histamine receptor blockers, histamine receptor antagonists): These active ingredients can be used both for local therapy and systemically for the whole body. Typical symptoms of the nose and eyes respond quickly to antihistamine sprays and drops. Tablets with modern antihistamines such as cetirizine and loratadine rarely cause side effects such as tiredness and drowsiness. However, users react very differently. It is therefore advisable to try out the means before taking part in road traffic. To be on the safe side, they should be taken before bedtime, as their effects generally last for 24 hours. The targeted use of older antihistamines as sleep aids in children should only be done in individual cases and in compliance with age and weight restrictions.
- Mast cell stabilizers: These active ingredients (e.g. cromones such as cromoglicic acid) prevent the mast cells from releasing histamine and other messenger substances. To do this, the drugs need a certain lead time, which means that they do not work immediately, but with a delay. The most common possible side effects include nasal irritation.
- Glucocorticoids (e.g. cortisone): Cortisone preparations are hormones produced by the adrenal cortex or are chemically derived from adrenal cortex hormones. They have a strong antiallergic and anti-inflammatory effect. Specialists recommend them especially when antihistamines and mast cell stabilizers do not help. As a nasal spray, they take a few days to show their full effect. There are now also low-dose nasal sprays that do not require a prescription for adults. But these nasal sprays also have side effects such as headaches, nosebleeds, colds and coughs, which is why they should not be used for more than three months without professional advice. These nasal sprays are not recommended for children and young people. Pregnant and breastfeeding women should seek advice from their doctor or pharmacist before taking them.
- Beta-2 sympathomimetics (e.g. salbutamol, fenoterol, salmeterol): These drugs dilate the bronchi. They are contained in asthma sprays against acute attacks or in longer-acting agents for long-term therapy.
- Leukotriene antagonists (e.g. montelukast): The docking sites of certain messenger substances (technical term: leukotrienes) are blocked by these active substances. Agents such as montelukast take those affected as tablets or chewable tablets once a day and can do without the inhalation that is usual for asthma patients. Therefore, these drugs are often used in children. The most common possible adverse effects include diarrhea, nausea, vomiting, rash, upper respiratory tract infection, and fever.
Specific immunotherapy or hyposensitization
Hyposensitization, desensitization or allergy vaccination is considered by experts to be the only therapy that addresses the cause and not just treats the symptoms (technical term: allergen-specific systemic immunotherapy, abbreviation: ASIT or SIT). Desensitization works in such a way that with slowly increasing doses of the substance causing the allergy, the immune system becomes accustomed to tolerate the allergen. Specific immunotherapy usually lasts three years.
There are two methods: In subcutaneous immunotherapy (SCIT), the allergen is injected under the skin. In sublingual immunotherapy (SLIT), the allergen is given as a tablet under the tongue (active ingredient: Acarizax). Subcutaneous immunotherapy is more complex because the person concerned has to see a doctor for each treatment (weekly at the beginning, monthly or every two months later) to wait for a possible allergic reaction.