Mites

All mites (Acari, about 10,000 species) belong to the arthropods (arthropods) and here to the arachnids (Arachnida). They are divided into a number of orders, especially with regard to the formation of their respiratory openings (astigmata: no respiratory openings; prostigmata: respiratory openings in front, cryptostigmata: respiratory openings hidden, mesostigmata: respiratory openings in the middle, metastigmata: respiratory openings behind).

In addition to their infectiological significance in the transmission of various pathogens (e.g. rickettsialpox, tsutsugamushi fever), they can cause skin lesions through bites.

The mites most frequently responsible for allergic diseases belong to the superfamilies Pyroglyphphoidea with house dust mites (Dermatophagoides pteronyssinus, Dermatophagoides farinae, Euroglyphus maynei) and Acarideae(storage mites).

• Human Scabious Mite: The 400 x 300 μm large (Acarus siro var. hominis or Sarcoptes scabiei hominis) has four pairs of legs and very strong jaws. The only host is the human being. Mites survive outside the host (e.g. in clothing and bedding) for 2-3 days. On average, a patient accommodates only 11.3 (!) adult female mites. 3% of the patients have > than 50 mites, the maximum being about 500. For the infestation of a new victim a single mated female is sufficient.
• Generation cycle of the human dross mites:
• Multi-stage metamorphosis. The total development time for males is 9-14 days, for females 12-21 days.
• Female mites are able to move about 2.5 cm/min. on the human skin and drill blind ending corridors parallel to the skin surface into the horny layer. Since the mites breathe through the body surface, they can only penetrate as far as the stratum corneum and not deeper. Only 1 female mite lives in each passage. They feed on drilled skin, lengthen the passage daily by about 0.5-5 mm and lay 2-3 eggs/day as well as debritus and faeces in the passage. 3-7 days later larvae hatch from the eggs. In search of food, larvae leave their passage, shed their skin after about 3 days and reach the protonymph stage. 3 days later, protonymphs either shed their skin and differentiate into adult male mites or enter a second nymph stage (tritonymphs). From tritonymphs either adult sexually mature males or females develop. Adult mites mate on the skin surface or in short (< 1 mm) ducts drilled for mating alone.

• Herb mite (Sarcoptes scabiei var. hominis): Clinic: see below scabies. Worldwide occurrence, usually transmitted directly by physical contact, more rarely also indirectly, e.g. by bedding in hotels.
• Dog mite ( Sarcoptes scabiei var. canis): Worldwide occurrence, living on dogs and causing mange there. Passes over to humans in close contact.
• Horse Cattle Cat Mite: Man is, just as in the case of dogs, also a false host in the case of cat ruff and horse scabies, mites cannot settle down and perish ( pseudoskabies); see mange below.
• Bird mite (Dermanyssus avium): Worldwide occurrence, especially in chickens, also in pigeons and various songbirds, in stables and nests. The mites can, under certain circumstances, penetrate into the house through windows of the ventilation systems. Man is a false host (see below gamasidiosis).
• (Tropical rat mite (Ornithonyssus bacoti ): Occurs in tropical countries, also in Europe. Man is a false host.
• Grave mite (Trixacarus caviae): most common dermatosis (Sarccoptes mange) in small mammals (rabbits, guinea pigs). Rarely transmitted to humans in close contact with infested animals.
• Cheyletiella mite (Cheyletiella yasguri): Occurs worldwide in dogs, rabbits, hares, cats, rarely passes to humans in close contact with infested animals S.u. Cheyletiellosis.
• Harvest mite (Trombicula autumnalis): In Europe mainly in autumn. Humans are attacked by the larvae when walking in the Alps (Clinic: Trombidiosis).
• Grain beetle mite (Pyemotes ventricosus): Occurs mainly in Mediterranean countries and in Northern Europe. The mite feeds on cereal pests and is therefore found in grain stores, barns and on straw mattresses. Woodworms are also infested.
• Other mite species:
  • (House dust mite: Dermatophagoides pteronyssinus, Dermatophagoides farinae) .
  • Acarus firo: flour mite
  • hair follicle mite ( Demodex folliculorum)
  • Cheese mite.

• Scabies mite: S.u. Skabies.
• Dog mite: S.u. dog buildings.
• Cat mites: See also cat nests.
• Horse mite: See and horse scabies.
• Bird mite: Gamasidiosis or bird mite scabies. On uncovered body parts strongly itchy papulovesicular, partly urticarial efflorescences. No mite detection on the skin.
• Tropical rat mite: Small papulovesicular, partly urticarial lesions. Preferably occurring in places with tight-fitting clothing.
• Cheyletiellosis: Predilection sites of cheyletiellosis are arms and trunk. Maculopapular lesions, partly with vesicles and pustules.
• Harvest mite: Trombidiosis; preferentially occurring in places with tight-fitting clothing.
• Grain weevil mite: ( cereal dross) small spotted, usually papular, occasionally urticarial exanthema. S.a. Pyemotes ventricosus dermatitis).
• hair follicle mite ( Demodex folliculorum): pathogen of demodicosis (Demodex folliculitis).
• Cheese mites: S.u. and herbal scabies.

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