Dust Mites Up Close and Personal

The dust mite, a cosmopolitan guest in a human habitation. Dust mites feed on organic detritus such as flakes of shed human skin and flourish in the stable environment of dwellings. Dust mites are a common cause of asthma and allergic symptoms worldwide. The mite’s gut contains potent digestive enzymes that persists in their feces and are major inducers of allergic reactions such as wheezing. The mite’s exoskeleton can also contribute to allergic reactions.

The body of a dust mite is just visible against a dark background in normal light. A typical dust mite measures 0.4 millimetres (0.016 in) in length and 0.25-0.32 millimetre (0.0098-0.013 in) in width. Both male and female adult dust mites are creamy blue and have a rectangular shape. The body of the dust mite also contains a striated cuticle. Dust mites have eight legs

The average life cycle for a male dust mite is 10 to 19 days. A mated female 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 dust mite will produce approximately 2,000 fecal particles and an even larger number of partially digested enzyme-covered dust particles.

Dust mite survives in all climates, even at high altitude. Dust mites thrive in the indoor environment provided by homes, specifically in bedrooms (mattresses) and kitchens. Dust mites survive best in mattresses, carpets, furniture and bedding, with figures around 188 animals/g of dust. Even in dry climates, dust mites survive and reproduce easily in bedding (especially in pillows), deriving moisture from the humidity generated by human breathing, perspiration and saliva.

Dust mites consume minute particles of organic matter. Dust mites have a simple gut; they have no stomach but rather diverticulae, which are sacs or pouches that divert out of hollow organs. Like many decomposer animals, they select food that has been pre-decomposed by fungi.

Allergens produced by dust mites are among the most common triggers of asthma. 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.

Typical symptoms of dust mite allergies are itchiness, sneezing, inflamed or infected eczema, watering/reddening eyes, sneezing repeatedly and frequently; e.g., on waking up sneezing 10 or more times, runny nose and clogging in the lungs.

At present, the best form of treatment for dust mite allergies is avoidance of dust mites and their allergens combined with medication such as anti-histamines. The environment of bedding is optimal for most dust mites, and comparative studies have shown that the density of dust mites in mattresses to be on average greater than 2500/gram of dust.  Cleaning beds with most vacuum cleaners will not remove dust mite allergens, but instead throw them into the air and increase their volatility. Some bedding is beneficial as it makes the environment difficult for the dust mites. This bedding should also be breathable (wool) and be able to withstand frequent washing. A home allergen reduction plan has been recognized as being an essential part to the management of asthma symptoms  and therefore all aspects of the home environment should be considered (proper vacuuming, use of air cleaners, etc.)


It is commonly believed that the accumulated detritus from dust mites can add significantly to the weight of mattresses and pillows. Fecal matter of dust mites will increase over time.

Allergy and asthma sufferers are also often advised to avoid feather pillows due to the presumed increased presence of the house dust mite allergen.  Polyester fibre pillows contained more than 8 times the total weight of detritus and 3.57 times more micrograms of detritus per gram of fine dust than feather pillows.

A simple washing will remove most of the waste matter. Exposure to temperatures over 60 °C (140 °F) for a period of one hour or freezing, exposure to temperatures below 0 °C (32 °F), will typically prove fatal to dust mites; a relative humidity of less than 50% may also be fatal. Ten minutes in a household clothes dryer at lethal temperatures has been shown to be sufficient to kill all the dust mites in bedding. Dust mites reproduce quickly enough that their effect on human health can be significant.

As dust mites like warm, fluffy furniture and materials, they are most likely to be found on beds, couches, carpets, rugs, toys, and curtains. Washing will not completely remove all mites or their droppings, but it will remove at least 90%. It is best to have a carpet free house if dust mites or any house pests are dangerous for a person as flat surfaces are easier to clean and vacuum. If a person is allergic to dust mites, anti-mite mattresses or mattresses which prevent any house pests should be used. Rubber mattresses are not dust mite friendly.  Regular cleaning and washing of areas where dust mites thrive is necessary to keep them and their waste to a minimum.

Asthmatic patients should avoid using feather filled pillows. Pillows with synthetic fillings are also a risk factor for severe asthma. Wool or latex pillows are not dust mite friendly.


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