Generality
Dust mite allergy is one of the most important and widespread allergic forms in Western countries. The culprit is a microscopic arthropod (Dermatophagoides pteronissinus And flour and), widely spread in the environment and capable of provoking, in sensitive subjects, a powerful immune reaction (often erroneously defined as "dust allergy").
What is an allergy
Allergy is an abnormal and excessive response of the immune system (hypersensitivity of the allergic subject) to usually harmless substances, 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 instead harmless and, if they come into contact with the defense system, they are ignored.
In predisposed people, the body triggers an immune reaction to specific allergens. Allergy therefore consists of an abnormal and exaggerated response of the immune system to contact with foreign substances, normally harmless and well tolerated by non-allergic subjects, to whom cause no problem.
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 that has entered the body and induce the reaction of T lymphocytes, which produce specific IgE against the allergen. IgE enters the circulation and adheres to the membrane of mast cells, 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, leukotrienes 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 frequently causing 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 from 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. The Mites Dermatophagoides
As their name says, the Acari Dermatophagoides (skin eaters), they feed mainly on human desquamation, which continually detaches from our body. This species is only alive for eight weeks but, under favorable conditions, it reproduces very easily. Females can lay one egg per day.
Where are
In every home, even the cleanest, there are mites: in the beds there are over 94% of their allergens, in every gram of dust there are from 2,000 to 15,000 mites.
The mites find in our homes an ideal environment and the conditions necessary for their existence:
- Absence of sunlight. Mites do not tolerate light, which is why they nest in cushions, in the inner layers of the mattress, in carpets, soft toys, curtains, carpets and all other objects that easily retain dust, but also among the flakes of skin death and dandruff.
- The high temperature and humidity favor its growth. Microscopic arthropods proliferate best at temperatures above 20 ° C and relative humidity between 60-80%.
- Food in large quantities. Mites can feed on anything organic they can find 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 mite have been identified: however, the most common in our homes belong to the god family Pyroglyphidae (or house mites), the most allergenic members of which are:
- Dermatophagoides pteronissynus;
- Dermatophagoides farinae;
Rarely, however, the following species are encountered, also called minor or foodstuff mites:
- Blomia tropicalis
- Acarus Siro
- Tyrophagus putrescentiae
1-15% of the housing dust mite population. They prefer particular environments (food warehouses, granaries, barns). They are less potent allergens.
Allergens of the mite
It is not the mites themselves that cause the allergic reaction, but the "major allergens", substances present mainly in the droppings, secretions and dead body of the mite.
In particular, the allergenic particles can be made up of enzymes present in the fecal particles of the mite; these, once released into the air, are easily inhaled, triggering respiratory allergies. The allergens remain deposited in the place where they are produced by the mite (mattresses, pillows, etc.) and accumulate in quantity. Contact with the allergenic particles occurs through the respiratory tract, since the movements of the human body lift them, allowing their uptake.
Period of exposure to allergens
Dust mite allergy belongs to the group of perennial allergies, which occur all year round. There is no fixed periodicity, but the symptoms can intensify especially in the winter period, when the ideal conditions for the growth of mites are created inside the heated and poorly ventilated houses.
Other articles on "Allergy to Dust Mites"
- Allergy to dust mites: symptoms, diagnosis and treatment
- Allergy to mites - Remedies and Prevention
