Hair follicle mites
| Hair follicle mites | ||||||||||||
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Demodex canis (250 to 300 µm long) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Demodex | ||||||||||||
| Owen , 1843 |
As demodex is called mites , which in the hair follicles (follicles) of mammals parasitize . The numerous, mostly host-specific species all belong to the single genus Demodex (from ancient Greek demos 'tallow' and dex 'woodworm') in the family Demodicidae. They were discovered by Gustav Simon in 1842.
Hair follicle mites are small, conical mites about 100 to 400 µm in length. They consist of the mouth area ( Gnathosoma ), the front part ( Podosoma ) with four stocky pairs of legs, which have small blunt claws at the end , and the abdomen ( Opisthosoma ). The body and legs have no bristles. Trachea are missing, the intestine is rudimentary and has no anus, so the feces remain in the body for life.
From their developmental stages of egg, larva , protonymphe , nymph and adult , the protonymphe stage is occasionally omitted. Under special conditions, an infestation in the host can lead to skin disorders known as demodicosis .
The two species that colonize human skin , Demodex folliculorum and Demodex brevis , are mostly to be regarded as harmless (ecto-) commensals . The almost transparent, up to 0.4 mm long animals can be found in almost all people of older age and feed on the secretion of the sebum glands . A connection with rosacea and inflammation of the Meibomian glands (a type of gland that is responsible for the thick part of the tear fluid that serves as protection against evaporation) via cross-contamination with the bacterium olerinus is under discussion.
The eradication of the mites with the help of intense light pulses instead of chemical therapeutics has been confirmed in small studies.
Systematics
In 2009, Clifford Desch gave the number of species as 86, including:
- Demodex antechi
- Demodex brevis : human hair follicle mite
- Demodex bovis : hair follicle mite of cattle
- Demodex canis : hair follicle mite of the dog, see also Canine demodicosis
- Demodex caprae : hair follicle mite of goats
- Demodex cati : hair follicle mite in cats, see also demodicosis in cats
- Demodex caviae : hair follicle mite of guinea pigs
- Demodex cornei : hair follicle mite of the dog (→ Canine demodicosis)
- Demodex equi : hair follicle mite of the horse
- Demodex folliculorum : human hair follicle mite
- Demodex gapperi
- Demodex gatoi : hair follicle mite in cats (→ demodicosis of cats)
- Demodex injai : hair follicle mite in dogs (→ Canine demodicosis)
- Demodex ovis : hair follicle mite of sheep
- Demodex phyloides : hair follicle mite of pigs
literature
- Clifford E. Desch: Human hair follicle mites and forensic acarology. In: Experimental and Applied Acarology , Volume 49, No. 1/2, 2009, pp. 143-146, doi: 10.1007 / s10493-009-9272-0 .
Web links
Individual evidence
- ↑ a b Tanja Töpfer: Diagnosis and therapy of demodicosis in dogs and cats . In: Kleintierpraxis Volume 65, 2020, Issue 8, pp. 444–459.
- ↑ Richard Wall, David Shearer: Veterinary Ectoparasites. Biology, Pathology and Control. 2nd Edition. John Wiley & Sons, New York NY 2008, ISBN 978-0-632-05618-7 , p. 44.
- ↑ Clifford Desch: Human hair follicle mites and forensic acarology. In: Experimental and Applied Acarology. Volume 49, Issue 1/2, October 2009, pp. 143–146.
- ^ A b Steven J. Dell: Intense pulsed light for evaporative dry eye disease. June 20, 2017, accessed October 27, 2019 .
