What are mites?
The order of Acari (or Acarina) is divided into 5 families, 18 genera and about 50,000 species. This order belongs to the Arachnida Class, meaning that mites are of the same class as spiders and scorpions. There are about ten species of dust mites that are particularly well-known, and that are responsible for allergies. Currently, it is estimated that ten percent of the population is positive to skin allergy tests for dust mites.
Dust mites are 200 to 500 µm (2 to 5 tenths of a mm) in size and are therefore only visible under a microscope: it is their small size, and more precisely that of their excrements, which allows them to pass through our respiratory tract and make them antigens that can trigger the development of antibodies in the respiratory mucosa. These antibodies are responsible, during further contacts with the antigen, of the reactions that cause rhinitis or asthma.
Starting at 800 meters above sea level, mites gradually disappear (the effect of altitude on mites is mainly due to more severe climatic conditions in the mountains). Low temperatures require heating in all seasons, which considerably reduces air humidity.
House dust is a mixture of various elements, in which we always find mites, but also textile fibers, hair, human skin fragments, insect waste, cat and dog hair, molds, pollens, and so forth. According to some authors, house dust is responsible for 50% of allergies, and it contains up to 45 different allergens.
A mite can drop more than 20 excrements with a diameter of about 10 µm per day. These may be inhaled, in whole or in part, through the respiratory tract and release their allergenic enzymes. It can be assumed that the risk of clinical sensitivity arises when we reach an equivalent amount of about 100 mites per gram of dust. Asthma is triggered when this amount reaches 500 mites per gram.
How do we fight dust mites?
We can deal with them at several levels and, first of all, limit their number by maintaining “climatic” conditions that are unfavorable to their development. The temperature should not exceed 20°C, 18°C being ideal in the bedroom, preferably constantly heated to maintain low humidity. Since is humidity, more than temperature, that must be strictly controlled, a reduction of 10 to 15% in relative humidity produces a high decrease in the allergenic material excreted by the mites.
Prevention will also consist in eliminating all places where the mite is housed, like carpets, rugs and upholstery (mattresses, cushions, sofas filled with kapok, feathers, hair, straw, etc.), especially in the room of the person with allergy.
The bed must be made of smooth material with a bottom of slat or wire mesh; the mattress must be sufficiently ventilated, hence the need for a space between the floor and the mattress of at least 25 cm, not occupied by drawers or other bulky material. Do not use drawers under beds, bunk beds, mattresses with springs or box springs.
The mattress should be made of a synthetic material made of foam or synthetic fibers, polyether, latex or bultex. Any mattress, even made of synthetic material, can be heavily infested by Dermatophagoids after one year. It must be regularly turned, aerated and vacuumed. Mattresses with a wool side, often called winter side, should be avoided.
The pillow and any other cushions must be stuffed with synthetic fibers or foam; they must be regularly washed with water and renewed every year.
The sheets and pillowcase should be made of cotton or a synthetic material that allows it to be washed at over 60°C; they should ideally be changed weekly.
Bedding must be very carefully cared for. A priority should be given to regular and thorough care of quilts, blankets and mattress protectors. They constitute a real “storage room”, sometimes as much as the mattress, mainly where there are topstitching, hems, buttons and so forth, in short in any tight place where dust can resist the mechanical action of leaching.
How to eliminate dust mites?
In the case of allergic people, dust mites must be carefully eliminated in order to limit their action. Many products are available on the market, generally containing synthetic pesticides such as deltamethrin or permethrin, which eliminate the famous mites. Regrettably, their long permanence in mattresses and sheets also generates sensitivity in the people who breathe these molecules.
In fact, even if mites will inevitably recolonize the bed, is it necessary to maintain a high level of pesticide after killing them? NO!
It is much better to use products without long-lasting pesticides, that will kill dust mites but will also disappear quickly enough to avoid people to get a sensitivity to another type of allergen like the pesticides.
To do this, it is preferable to use a product without pesticides, but based on essential oils that will kill dust mites and will also quickly vanish from textiles.
However, the treatment should be repeated approximately every 15 days and a vacuum cleaner, specially equipped with dust mite filters, should be used to vacuum the dead bodies of the mites.