Dust Mite

House dust mites are microscope bugs that primarily live on dead skin cells regularly shed from humans and their animal pets. Dust mites are generally harmless to most people. They don't carry diseases, but they can cause allergic reactions in asthmatics and others who are allergic to their feces. People sometimes confuse dustmites with bed bugs.

Description

House dust mites, due to their very small size and translucent bodies, are barely visible to the unaided eye.A typical house dust mite measures 0.25–0.3 millimetres (0.010–0.012 in) in length.For accurate identification, one needs at least 10× magnification. The body of the house dust mite has a striated cuticleM

Detecting

House dust mite presence is often suspected before they are actually seen and accurately identified. Requests for control often come from individuals who have been diagnosed by medical personnel as allergic to the house dust mite or the allergens produced. The presence of house dust mites can be confirmed microscopically which requires collecting samples from mattresses, couches or carpets. Also, it requires the use of a microscope with sufficient magnification and the technical ability to recognize house dust mites under the microscope. In general practice, testing is unnecessary. dustmites are extremely common in household environments. They virtually always show up in a test, so testing just adds expense.

Life cycles

The average life cycle for a male house dust mite is 10 to 19 days. A mated female house dust mite can last up to 70 days, laying 60 to 100 eggs in the last 5 weeks of her life. In a 10-week life span, a house dust mite will produce approximately 2,000 fecal particles and an even larger number of partially digested enzyme-covered dust particles.

Habitat and food

The house dust mite survives in all climates, even at high altitude. House dust mites thrive in the indoor environment provided by homes, specifically in bedrooms and kitchens. Dust mites survive well in mattresses, carpets, furniture and bedding, with figures around 100–500 animals/g dust.Even in dry climates, house dust mites survive and reproduce easily in carpets and bedding (especially in pillows), which takes up moisture from body contact.

Common beliefs and misconceptions

It is commonly believed that the accumulated detritus from dust mites can add significantly to the weight of mattresses and pillows. While some recent studies have supported this claim,other reports dispute it.However, more scientific evidence is needed for a complete consensus. Allergy and asthma sufferers are also often advised to avoid feather pillows due to the presumed increased presence of the house dust mite allergen (Der p I). However, according to a 1996 study from the British Medical Journal, the reverse is true. The study showed that polyester fibre pillows contained more than 8 times the total weight of Der p I and 3.57 times more micrograms of Der p I per gram of fine dust than feather pillows.

Eradication

House dust mites reproduce quickly enough that their effect on human health can be significant. Since dust mites depend on moisture to survive, they are most often found in bedding such as pillows and duvets.Dust mites numbers can be reduced by replacing carpets with flat surfaces that are easier to vacuum and maintaining relative humidity below 50%.Existing mites can be eradicated through ten minutes' exposure to the lethal temperatures – near 105 °C (221 °F) – in a household clothes dryer, or using disodium octaborate tetrahydrate (DOT) powder.[25] A side effect of DOT is irritation of eyes. The breakdown of feces produced by dust mite can be accelerated by eucalyptus oil. The eucalyptus oil from an aerosol can, when sprayed into fabric containing the mite feces, acts as a catalyst in the process of the feces's decomposition. The aerosols can be bought from supermarkets and chemists without a script. The use of eucalyptus plus regular vacuuming and insecticides is very effective[citation needed]. One method used to reduce exposure to dust mites and their feces is to encase all mattresses, duvets and pillows in tightly-woven, but not airtight, barrier covers which have been specially designed to be allergen-proof.

Asthma and allergies

Allergens produced by house dust mites are among the most common triggers of asthma. There are at least 15 mite allergens which are subdivided into groups. Group 1 and 2 allergens are the most problematic. Group 1 consists of proteins with a catalytic activity, for example Der p 1 (Dermatophagoides pteronyssinus group 1) allergen is a cysteine protease, as is its American counterpart Der f 1 (Dermatophagoides farinae group 1). Group 2 are proteins important for the mite. Proteins from the other groups affect only few patients.

Studies have shown the mean attributable fraction of adult asthma due to atopic sensitization was 30% and 18% for sensitization to dust mites.Taken into consideration this could mean as many as 1.2 billion people could have some form of chronic sensitization to dust mites.[6] The allergy occurs because the immune system of allergy-affected individuals, for reasons not fully understood, misinterprets a usually innocuous substance as a disease agent and begins producing a type of antibody against it, called immunoglobulin E (IgE).This is called the 'primary antibody response.' The IgE produced during this response binds to basophils in the bloodstream and to a similar type of cell called mast cells in the tissues. When the person again encounters the allergen, these basophils and mast cells that have bound to IgE release histamine, prostaglandins and leukotrienes, which causes inflammation of the surrounding tissues, resulting in allergic symptoms.

Newer methods to try to treat house dust mite allergy involve Allergy immunotherapy. Allergen immunotherapy rehabilitates the immune system by administering increasing doses of house dust mite allergens to accustom the body to the substance and thereby induce specific long-term tolerance.Allergen immunotherapy can be administered under the tongue (sublingually with drops or tablets) or by injections under the skin (subcutaneous). Discovered by Leonard Noon and John Freeman in 1911, allergen immunotherapy represents the only causative treatment for respiratory allergies. Allergy immunotherapy company ALK currently produces subcutaneous immunotherapy (SCIT) and sublingual immunotherapy drop (SLIT-drops) treatments for house dust mite allergy, and is carrying out clinical development work on a new, sublingual immunotherapy tablet (SLIT-tablet) treatment for house dust mite-induced respiratory allergic disease. Conducted as part of partnership agreements with Merck & Co[10] and Torii Pharmaceutical Co,this program is the largest clinical development program in the history of allergy immunotherapy and involves more than 6,000 patients in Europe, Japan and the USA.