The possibility of developing an allergy to dust mites is practically the only danger to humans from these microscopic creatures. In this case, an allergic reaction is an excessively acute response of the human immune system to contact with certain substances secreted by ticks and contained in the integument of their bodies.
Pathology can manifest itself with symptoms of varying severity - from minor nasal congestion or subtle skin irritations to severe bronchial asthma and deadly anaphylactic shock.
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According to statistics, it is allergy to house dust mite antigens that is the most common cause of bronchial asthma worldwide. It is also the leading etiological factor in a huge number of cases of chronic rhinitis and other pathologies of the respiratory tract. Often people do not even suspect that the reason for their regular nasal congestion is precisely house dust with the waste products of dermatophagous mites contained in it.
At the same time, dust mites are not human parasites, they do not bite him, do not settle on his body and do not spoil food. For people who do not suffer from tick allergies, they do not pose any danger at all.
The photograph below, taken with an optical microscope, shows the dust mite Dermatophagoides pteronyssinus:
And this is what it looks like under an electron microscope:
Nevertheless, the epidemiological significance of dust mites is very high: the number of cases of allergy to them is in the millions around the world, and not a single person is immune from its development, no matter how strong his health (immunity) is and no matter how clean his housing is . Moreover, as we will see later, the cleanliness of the house and strong immunity are factors that contribute to the development of allergies rather than protect against it ...
The mechanism of development of allergy to dust mites
It is known that the immune system develops a specific immune response to many substances that enter the blood or internal tissues of the body and are genetically alien to it. If this substance enters the body again in the future, agents of the immune system quickly neutralize it and prevent a possible threat to the body from this substance.
Substances with a foreign genetic structure that the immune system identifies as suspected to be dangerous are called antigens.
The immune system overreacts to some of these substances. When an antigen enters the blood or any tissue, an overly violent reaction of the immune response immediately starts, the manifestations of which often turn out to be more harmful and dangerous than the antigen itself. And in many cases, the antigen does not pose a threat to the body at all (for example, the waste products of dust mites), although it is identified by the immune system as a dangerous substance.
Such an excessive reaction is called an allergic reaction, or more simply, an allergy.Antigens that cause this overreaction are called allergens. In fact, based on modern understanding of physiology, allergies can be considered an error of the immune system in distinguishing between dangerous and harmless foreign particles.
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Why do such errors occur? It is believed that this is due to the excessive "sterility" in which people live. The human immune system, adapted over millions of years to contact and neutralize a huge number of antigens, in the conditions of modern civilization is "underloaded". As a result, it begins to overreact to relatively safe substances.
Confirmation of this hypothesis is the fact that the frequency of allergy development is inversely correlated with the standard of living in a given area. Simply put, the worse the sanitary conditions in which people live, the lower their likelihood of developing an allergy to any substance. At the same time, statistics clearly show that the frequency of allergies in adults who emigrated, for example, from Africa or India to the United States, increases after moving compared to the same frequency among their peers who remained at home.
Typical allergic rhinitis is a truly "adult" disease. Children practically do not get sick with them, since their immune system is already loaded with adaptation to unfamiliar antigens.
The occurrence of an allergy to a particular substance is called sensitization of the body, and a person with such an allergy is called sensitized. Accordingly, when an allergy to dust mites occurs, they speak of tick sensitization. These terms come from the English word "sensibility" - sensitivity, and allergy itself in scientific circles is often referred to as hypersensitivity.
To make the mechanism of development of dust mite allergy even more understandable, it is worth taking into account the following fact: the more complex the structure of the antigen and the more biological activity it has, the higher the likelihood that it will cause an allergy. That is why allergies are most often caused by plant pollen, animal hair and bird fluff, various berries and fruits - they all contain complex functional proteins with a large molecular weight, which the “idle idle” immune system will most likely pay attention to.
Three types of allergens are associated with dust mites:
- Digestive enzymes contained in the gastrointestinal tract of these arthropods and excreted in feces. Due to their microscopically small size and negligible weight, such feces easily rise into the air with dust and are just as easily inhaled by a person, and then cause a hypersensitivity reaction in the upper respiratory tract or in the bronchi;
- Particles of chitinous covers (cuticles) of ticks that enter the air along with dust during the molting of these creatures, as well as after the death and drying of their bodies;
- Substances contained in the internal organs of ticks that enter the human digestive tract when live ticks are swallowed with dust and food.
It is believed that the largest number of cases of allergy to dust mites are associated with two digestive enzymes contained in feces - Der f1 and Der f2. These enzymes are very aggressive towards the cells of the skin and mucous membranes, since they are designed specifically for the digestion of particles of the dermis (skin) - the main food of mites. For this reason, these allergens can cause allergic dermatitis.
In most cases, house dust mite allergy is cross-species. That is, if sensitization has occurred, for example, to the antigens of the European dust mite Dermatophagoides pteronyssinus, then when meeting with the American Dermatophagoides farinae, a person will also develop an allergy.
Less common is cross-allergy to antigens of ticks and various synanthropic insects - cockroaches, bedbugs, fleas. In this case, sensitization occurs not to species-specific enzymes, but to certain components of the chitinous integuments that are present both in ticks and other arthropods in the room. It is less likely to develop a cross-allergy between mites and other components of household dust.
Like any allergy, only a part of people develop a reaction to dust mites, and the likelihood of development and its strength do not depend on the general state of human health and the strength of his immunity. There is even an opinion that the stronger the immune system of a particular person, the more likely it is that he may develop an allergy (however, this hypothesis has not yet been sufficiently confirmed by special studies).
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Similarly, there is reason to believe that the cleaner the rooms in which an adult has lived most of his life, the higher the risk that this person will develop an allergy when encountering dust mites.
Studies have shown that the development of allergy to dust mites most often occurs when their number increases to a level of more than 100 individuals per 1 g of house dust. At the same time, on average, in all the apartments examined in the framework of the experiments, the number of ticks exceeded these indicators and amounted to 400-500 individuals/g, and in some apartments it reached 3500 individuals/g.
It is important to understand that dust mites and their waste products are found in almost every living space in the world without exception (and also outside of human habitation, if conditions with a suitable microclimate and food are available). This means that most people have some form of exposure to dust mites, and there is always a risk of developing allergies.
Typical symptoms of an allergic reaction to dermatophagoids
Manifestations of allergy to dust mites differ little from the symptoms of other allergic diseases, but according to certain signs, the corresponding reaction can be recognized even without special instrumental diagnostics.
Most often, an allergic reaction to dermatophagoid mites occurs in the form of one of the following diseases:
- Allergic rhinitis, which develops frequent severe cough, runny nose, nasal congestion, pain in the eyes, sneezing;
- Chronic rhinitis, in which some of the symptoms may be absent. For example, a person has only nasal congestion without a runny nose (especially at night), or a runny nose, but without conjunctivitis and cough;
- Rhinoconjunctivitis, in which the leading symptoms are a runny nose and nasal congestion, redness of the eyes, tearfulness, pain in the eyes and the appearance of thick discharge from them;
- Atopic dermatitis, which develops in different parts of the body in the form of redness, cracking crusts, itching and cracks in the skin.
If a person has tick sensitization, each new episode of allergy is usually more severe than the previous one.The difference in severity is not always noticeable, but over time, the patient notes that the symptoms of the reaction have become more pronounced, and the general condition worsens much more.
For example, it is in this scenario that asthma develops. Initially, only the mucous membrane of the upper respiratory tract is involved in the allergic reaction. Then the process spreads to the middle and lower parts of the respiratory tract until swelling of the inner surfaces of the bronchi begins.
Similarly, atopic dermatitis can be complicated by, for example, urticaria.
Anaphylaxis due to contact with dust mites was registered only in cases where mites in large numbers entered the digestive tract. Life-threatening conditions that have developed when tick-borne allergens come into contact with the skin or in the respiratory tract are not described.
An important feature of allergy to dust mites is its confinement to living quarters, most often to a person’s house. In this, it differs significantly from most other allergies: for example, it happens that a person feels normal at home, but begins to sneeze or choke only on the street - with poplar fluff flying or in the spring when certain plants bloom. Conversely, with tick-borne allergies, symptoms appear or worsen precisely at home, where a person comes into contact with dust. In the fresh air in such cases, a person feels better.
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It is not uncommon for a child to have an actual allergy when parents keep him indoors for a long time "with a cold."Parents are afraid to let a “cold” child out into the street so that it “does not blow” again, they are waiting for the runny nose to pass, and the runny nose not only does not go away, but is aggravated precisely because of constant contact with the allergen.
It is only possible to make sure that the allergy is caused by tick-borne antigens only with the help of special studies (see below).
Diagnosis and confirmation of the etiology of the disease in the clinic
Allergy to dust mites must be differentiated from sensitization to other allergens present in the living room: various chemicals, pet hair, house plants, paints, fluff from pillows and much more.
Most often, this problem is solved by conducting skin allergy tests, also known as prick tests. Their principle is simple: if you deliberately introduce a small amount of an allergen into the body, then an unambiguous reaction will appear, while substances that are not allergens for a particular organism will not cause such a reaction. In this case, even if the allergy is usually manifested, for example, by rhinitis, then even subdermal administration of the allergen will cause an obvious skin reaction.
In practice, skin allergy tests are carried out as follows:
- An allergist examines the anamnesis and narrows down the spectrum of possible allergens. For example, if it is known that allergy symptoms appear mainly in the house, then allergens that the patient can only encounter on the street (plant pollen, for example) are not included in the experiment;
- An area of skin on the arm or back of the patient is cleaned with ethanol, and drops of solutions of histamine, sodium chloride and a set of alleged allergens are applied to it in the form of a mesh;
- A special lancet is applied to the site, which makes light, insensitive punctures of the upper layer of the skin precisely at the locations of the drops. In this case, the liquid with the allergen from each drop penetrates the skin;
- After a certain time (from several minutes to an hour), the doctor evaluates the reaction of the skin. Normally, histamine causes the most violent allergic reaction in any person, sodium chloride does not cause it at all, and at the site of its application, one can evaluate the skin's response to a puncture. The reaction at the injection sites of different allergens is compared with these standards. As a rule, during a standard test, redness of 3-4 mm in diameter appears at the site of exposure to the allergen, and redness does not develop at all at the injection sites of substances that are neutral for the body.
The results of such a study require professional interpretation. Not always a positive reaction to an allergen is evidence of an allergy. Therefore, the doctor should compare the results of the prick test with the data obtained during the collection of an anamnesis, the study of the symptoms of the disease, and the analysis of the reaction to other substances.
The photo below shows an example of the results of such a test:
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There are also diagnostic methods in which patients inhale aerosols with an allergen. They are less frequent, more dangerous, but in some cases more revealing.
In some cases, samples for chitin and other components of the outer integument of arthropods can give a positive reaction. In this case, only according to the test results, it is impossible to unequivocally state which specific “neighbors” in the apartment provoked an allergy. You can get an answer by conducting a survey of the premises: you can simply visually detect bedbugs, cockroaches or other insects visible to the naked eye.Here you should also examine the dust from several places in the room using a special test for dust mites - such a test allows you to determine the presence and concentration of mite antigens in the dust.
It is necessary to definitely suspect dust mites in the development of allergies when such a dust analysis gave a positive result, but no other insects could be found in the apartment.
In any case, all the results of such studies should be interpreted only by a doctor who understands the mechanism and causes of the development of allergies.
Treatment of dust mite allergy: desensitization as the main treatment
To date, there is only one method of completely curing dust mite allergy and several ways to relieve symptoms that give a temporary result.
A complete or sufficient cure is provided by antigen-specific immunotherapy (ASIT, or more simply - SIT), otherwise called desensitization. Its principle is that the patient is consistently injected with an allergen solution under the skin every 1-2 weeks for several months.
At first, the concentration of the allergen is very small - it is selected so that the body practically does not respond to it. With subsequent injections, the concentration is slowly increased, bringing in the last injections to significant amounts. With the correct implementation of such a series of injections, allergies never occur, and the body eventually adapts to large amounts of the allergen and no longer reacts to it under normal conditions.
In practice, complete desensitization is not always achieved.In most cases, the procedure is carried out until the body stops responding to the amounts of the allergen that it encounters in real conditions. This is enough for a dangerous allergy to no longer occur in a person, but hypothetically, the situation remains possible when the patient encounters a significantly larger amount of the allergen with the development of an appropriate reaction.
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In some cases, to obtain the desired result, only the initial course of ASIT is carried out. If after it the allergy persists, then a full course is carried out.
Sometimes ASIT is performed with resorption of the solution in the mouth. However, due to the partial breakdown of the allergen in the digestive tract, it is more difficult to accurately vary the amount of the substance, and in this form the procedure is carried out only when injections to the patient are contraindicated for any reason. Nevertheless, such drugs are gaining popularity due to the possibility of home treatment, and even special preparations for sublingual resorption are produced: Staloral "Tick Allergen", Allergovit. Similarly, injectable preparations are commercially available, for example, Alustal "Mite Allergen".
With all the advantages of ASIT, it has two drawbacks: long periods of treatment and relatively high cost. For this reason, it is not always rational to carry out this procedure: if an allergy develops in a person for a couple of days a year, then it is more rational to use means of quick temporary relief of an allergic reaction.
Remedies for relief of allergy symptoms
Antihistamines are considered the gold standard for allergy treatment.The principle of their action is that the active substance of such a drug blocks the receptors that react to histamine and trigger the allergic reaction itself. Even if the allergen enters the body and is recognized by the immune system, at the stage of activation of histamine receptors, the reaction fades and does not develop further. As a result, the external symptoms of an allergy in a person do not appear, and if they already exist, they disappear quite quickly.
Antihistamines come in a variety of forms, but for dust mite allergies, they are most commonly used as a nasal spray. It is these sprays that allow you to quickly stop the manifestations of allergic rhinitis. These include, for example, Histimet, Reaktin, Allergodil and others. The main advantage of such intranasal drugs is the absence of systemic side effects when they are used.
With dermatitis, rhinoconjunctivitis or urticaria, systemic antihistamines are prescribed in the form of tablets or syrups (for children). The principle of their action is similar to that for sprays, but they are active in all tissues of the body, and not just locally. The most famous systemic antihistamines include Suprastin, Diphenhydramine, Erius and some others.
Usually, antihistamines begin to act 30 minutes after ingestion, and the effect of their use lasts for 12-24 hours.
In allergic rhinitis, the following are also effective:
- Sprays based on corticosteroid hormones - they stop the allergic reaction at the injection sites, while they are quite safe, despite the seemingly dangerous "hormonal" nature. Their active ingredients do not penetrate into the blood and tissues and do not have any systemic effect on the body.Examples of such funds are Nasonex, Alcedin, Flixonase and others;
- Nasal decongestants - Naphthyzin, Galazolin, Tizin, which stop the symptoms of an allergic reaction for 3-6 hours and act very quickly. The effect of the use of the same Naphthyzinum appears within 2-3 minutes after administration. These drugs are very cheap and available, but chronic allergic rhinitis cannot be treated with them because of the risk of tachyphylaxis. It is noteworthy that some drugs contain both decongestants and antihistamine components (an example is Vibrocil).
On sale today there are also drugs that provide isolation of the surface of the nasal mucosa from allergens. These include, for example, Nazawal. However, studies have not shown significant improvement in the condition of patients with allergic rhinitis with the use of such agents.
If you are allergic to dust mites, washing your nose with a 0.9% solution of common salt is definitely useful, since this procedure cleans the nasal mucosa from allergens. However, not all people can carry out such washing (many are afraid of it) and, moreover, it does not provide complete relief of unpleasant symptoms.
Finally, folk remedies for treating tick allergies are ineffective, and sometimes even dangerous to health. To date, there is not a single natural remedy that would completely and quickly stop the symptoms of allergies. At the same time, most folk remedies positioned as anti-allergenic, in fact, can themselves cause severe allergic reactions.
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A striking example of a pseudo-drug in this case is chamomile.Her preparations are unknowingly considered hypoallergenic and are often used to treat allergies. At the same time, a significant number of people develop an allergy to chamomile, even at least one case of the death of a child from anaphylaxis is described, when parents tried to treat allergic rhinitis in an 8-year-old girl with chamomile.
As a result, if you need to get rid of the symptoms of an allergy to ticks here and now (as quickly as possible, in just a couple of minutes), then vasoconstrictor drugs are used. Antihistamines and hormonal sprays are used as means for a more or less "long distance". For a complete cure of allergies, specific immunotherapy is carried out.
Prevention of tick sensitization
Studies show that with the development of an allergic reaction to dermatophagous mites, simply removing them from the premises will no longer provide complete relief from unpleasant symptoms. This is due to the fact that both the mites themselves and their antigens are found almost everywhere, and therefore, even feeling normal at home, a sensitized person will feel signs of allergies in other places - at work, at a party, in many other rooms.
Therefore, tick-borne sensitization is wiser to prevent, instead of then being treated for a long time.
What you need to do for this:
- Remove as much dust as possible from your home. If there are suspicions of the presence of mites in it, it is useful to check the dust using special test systems, analyze the bed, sofa, bedding, pillows and mattresses for the presence of dermatophages, if necessary, replace or treat with hot steam those items from which mites cannot be removed ( the same mattresses).After removal, it is useful to use special agents that destroy antigens that remain in the apartment after the removal of the ticks themselves. An example of such a drug is Easy Air Allergy Relief Spray;
- Regularly carry out wet cleaning and ventilation in the apartment;
- If possible, eliminate unnecessary dust accumulators - open bookshelves, carpets and rugs;
- Use bedding with certain parameters: pore diameter no more than 10 microns, fabric impermeability for allergens - 99%, dust permeability no more than 4%, air permeability - 2-6 cm3/(sec*cm2);
- If pets live in the room, conduct a study of their hair, and if dust mites are found in it, remove them (mites of some species often settle in the hair of dogs, less often on cats).
If there are a lot of dust mites in the room, and even thorough cleaning does not significantly reduce their number (this happens extremely rarely), then arthropods are destroyed by chemical means - preparations based on pyrethroids, organophosphorus compounds, neonicotinoids. These include, among other things, such common means as the Executioner, Get, Xulat Micro, Raptor aerosols, Raid and others.
However, with a responsible approach to cleaning the apartment, the need for such a serious treatment of the premises almost never arises.
Useful video about dust mite allergy
And this is what dust mites look like inside the pillow
