Sarcoptes scabiei.ppt
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Transcript of Sarcoptes scabiei.ppt
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Sarcoptes scabiei
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Taxonomic classification
Class Arachnida Sarcoptes scabiei (sarcoptic mange mite, itch mite)
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Host spectrum
Domestic (sheep, goats, cattle, pigs, equids, dogs , rabbits) and wild animals, humans, other primates Each host is considered to have its own strain or variety, e.g. Sarcoptes scabiei var. equi and Sarcoptes scabiei var. hominis
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Geographic distribution
Probably worldwide
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Morphology
Adults - rounded body; females 0.33-0.6 mm long and 0.25-0.4 mm wide, males 0.2-0.24 mm long, 0.15-0.2 mm wide; 8 short legs, posterior 2 pairs do not extend beyond the body margin; unsegmented pedicels; mouthparts have a rounded appearance.
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Sarcoptes scabiei, the scabies or itch mite
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Life cycle (stages) Female mites tunnel into the epidermis , lay 3-5 eggs per day for a total of 40-50 eggs Six-legged larvae hatch from eggs Larvae and nymphs (proto- and deuto-) burrow into the stratum corneum and form pockets where they molt and feed Adult males and females develop and mate Life cycle requires 2-3 weeks to complete
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Site of infestation
Skin (epidermis); females, eggs, larvae and nymphs in tunnels or pockets, males on the skin surface.
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Pathogenesis/clinical signs
Initial lesions occur on the hand, elbows, axillary or inguinal regions Lesions are initially erythematous, then become papular; papules rupture and skin becomes crusty Alopecia, thickening of the skin, pruritus Secondary bacterial infection, allergic reaction, self-mutilation may occur
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A severe case of scabies of the hand.
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Crusted appearance on hands
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Treatment
Lindane shampoo or dip, phosmet (ParamiteR), or Amitraz (MitabanR) ivermectin weekly for four weeks orally or subcutaneously
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Public health significance
Humans may be infested with the strains from animals and these infestations may be mild to intensely pruritic, but they are self-limiting.