Generality
Dust mite allergy is one of the most important and widespread allergies in Western countries. The person responsible is a microscopic arthropod ( Dermatophagoides pteronissinus and farinae ), widely distributed in the environment and able to cause, in sensitive subjects, a powerful immune reaction (often mistakenly called "dust allergy").
So it is an allergy
Allergy is an abnormal and excessive response of the immune system ( hypersensitivity of the allergic subject) to substances that are usually harmless, called allergens .The immune system has the task of protecting the body from the attack of harmful elements, such as viruses, bacteria and toxins. Other substances are harmless and, if they come into contact with the defense apparatus, they are ignored.
In predisposed people, the body triggers an immune reaction to specific allergens . The allergy consists, therefore, in an abnormal and exaggerated response of the immune system to contact with foreign substances, normally harmless and well tolerated by non-allergic subjects, to which they do not cause any problems.
The allergic reaction is mediated by class E immunoglobulins ( IgE ). In the allergic individual, these antibodies are produced when he comes into contact with the allergen to which he is sensitized, causing an abnormal response that induces the typical disorders of allergies.
The allergic process develops in two distinct phases:
- Sensitization : the immune system identifies the substance as an allergen. This phase takes place silently after the first contact. Macrophages identify the substance penetrated into the body and induce the reaction of T lymphocytes, which produce specific IgE against the allergen. IgE circulates and adheres to the mast cell membrane, defense cells located in the skin, lungs and nose. The mast cells will have the task of identifying the allergen when it comes into contact with the organism for the second time ( immunological memory ).
- The real allergic response appears on the occasion of a subsequent contact with the allergen, giving rise to the typical manifestations of allergy. The IgE present on the mast cell membrane recognize and capture the substance, causing the immune system to react and release various active chemicals (histamine, leukotriene and other elements). Prolonged or regular exposure to the allergen can cause the inflammatory response to become chronic and lead to disorders such as asthma.
Dust mites
There are different species of mites, but the most common allergic reactions are the Dermatophagoides mites . These microscopic animals feed mainly on small organic fragments that continually detach from the surface of the human body and domestic animals. The Dermatophagoides Mites are very small arachnids (measuring 200 to 600 µm), not visible to the naked eye, belonging to the family of ticks and spiders, which are found in many places commonly inhabited by people.
Note. Mites Dermatophagoides
As their name says, the Acari Dermatophagoides (skin eaters), feed mainly on human desquamations, which continually detach from our body. This species remains alive only eight weeks but, under favorable conditions, it reproduces very easily. Females can lay an egg a day.
Where are
In every home, even the cleanest, mites are present: in the beds there are over 94% of their allergens, in every gram of dust there are from 2, 000 to 15, 000 mites.
Mites find in our homes an ideal environment and the conditions necessary for their existence:
- Absence of sunlight . The mites do not tolerate light, for this reason they nest in the cushions, in the inner layers of the mattress, in the carpets, in the cuddly toys, in the curtains, in the carpet and in all the other objects that hold dust easily, but also between the flakes of skin dead and dandruff.
- The high temperature and humidity promote its growth. The microscopic arthropods proliferate better at temperatures above 20 ° C and relative humidity between 60-80%.
- Food in large quantities. Mites can feed on everything they can find organic in the home, such as mold spores, hair and dead skin cells from people and pets.
Note. Allergies are caused only by some species of mite.
As many as 50, 000 species of mites have been identified: however, the most widespread in our homes belong to the family of Pyroglyphidae (or domestic mites), whose most allergenic members are:
- Dermatophagoides pteronissynus;
- Dermatophagoides farinae;
Rarely, the following species are also encountered, also called minor mites or foodstuffs:
| 1-15% of the population of house dust mites. They prefer particular environments (food warehouses, barns, barns). They are less powerful allergens. |
Mite allergens
It is not the mites themselves that cause the allergic reaction, but the "major allergens", substances present mainly in the dejections, in the secretions and in the dead body of the mite.
In particular, allergenic particles can be made up of enzymes present in faecal mite particles; these, once released in the air, are easily inhaled, triggering respiratory allergies. Allergens remain deposited in the place where they are produced from the mite (mattresses, pillows etc.) and accumulate in quantity. Contact with allergenic particles occurs through the respiratory tract, since the movements of the human body lift them up, allowing their uptake.
Period of exposure to allergens
Dust mite allergy belongs to the group of perennial allergies, which occur throughout the year . There is no fixed periodicity, but the symptoms can intensify especially in the winter period, when, inside the houses, heated and poorly ventilated, ideal conditions are created for the growth of the mites.
