House dust mite

House dust mite
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Subclass: Acarina
Order: Acariformes
Family: Pyroglyphidae
Genus: Dermatophagoides
Species: D. pteronyssinus
Binomial name
Dermatophagoides pteronyssinus
(Trouessart, 1897)

The house dust mite (HDM) is a cosmopolitan pyroglyphidae that lives in human habitation. Dust mites feed on organic detritus such as flakes of shed human skin and flourish in the stable environment of dwellings. House dust mites are a common cause of asthma and allergic symptoms worldwide. The mite's gut contains potent digestive enzymes (notably proteases) that persist in their feces and are major inducers of allergic reactions such as wheezing. The mite's exoskeleton can also contribute to allergic reactions. The European house dust mite (Dermatophagoides pteronyssinus) and the American house dust mite (Dermatophagoides farinae) are two different species, but are not necessarily confined to Europe or North America; a third species Euroglyphus maynei also occurs widely. Unlike scabies mites or skin follicle mites, house dust mites do not burrow under the skin and are not parasitic.[1]

Description

House dust mites, due to their very small size and translucent bodies, are barely visible to the unaided eye.[2] A typical house dust mite measures 0.2–0.3 millimetres (0.008–0.012 in) in length.[3] For accurate identification, one needs at least 10× magnification. The body of the house dust mite has a striated cuticle.

Life cycle

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.[4]

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.[5] 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.[6]

House dust mites consume minute particles of organic matter. Like all acari, house 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 already partially decomposed by fungi.

Asthma and allergies

A scanning electron micrograph of a female dust mite
Main articles: Asthma and Allergy

House dust mites are associated with allergic rhinitis and asthma.[7] Efforts to remove these mites from the environment have, however, not been found to be effective.[7] Dust covers have also not been found to be effective.[8] Immunotherapy may be useful in those affected.[7] Subcutaneous injections have better evidence than under the tongue dosing.[9]

See also

References

  1. ↑ Barb Ogg. "Managing House Dust Mites". University of Nebraska-Lincoln. Retrieved 29 March 2015.
  2. ↑ "Why Study the Mite". Retrieved September 29, 2013.
  3. ↑ "The House Dust Mite". Retrieved March 29, 2015.
  4. ↑ "Allergia agli acari" (in Italian).
  5. ↑ "House Dust Allergy". American College of Allergy, Asthma & Immunology. Retrieved September 12, 2012.
  6. ↑ G. Daniel Brooks & Robert K. Bush (2009). "Allergens and other factors important in atopic disease". In Leslie Carroll Grammer & Paul A. Greenberger. Patterson's Allergic Diseases (7th ed.). Lippincott Williams & Wilkins. pp. 73–103. ISBN 978-0-7817-9425-1.
  7. ↑ 7.0 7.1 7.2 Biagtan, M; Viswanathan, R; Bush, RK (December 2014). "Immunotherapy for house dust mite sensitivity: where are the knowledge gaps?". Current allergy and asthma reports 14 (12): 482. PMID 25354663.
  8. ↑ Whitton, JL; Gebhard, JR; Lewicki, H; Tishon, A; Oldstone, MB (March 1988). "Molecular definition of a major cytotoxic T-lymphocyte epitope in the glycoprotein of lymphocytic choriomeningitis virus.". Journal of virology 62 (3): 687–95. PMID 2448497.
  9. ↑ Eifan, AO; Calderon, MA; Durham, SR (November 2013). "Allergen immunotherapy for house dust mite: clinical efficacy and immunological mechanisms in allergic rhinitis and asthma.". Expert opinion on biological therapy 13 (11): 1543–56. PMID 24099116.

External links