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Sarcoptes scabiei

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Sarcoptes scabiei Jeffery Cote Biology 4800 March 18, 2011 Cause of Scabies and Mange First identified by Aristotle 1868, formal discovery of scabies causative agent ... – PowerPoint PPT presentation

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Title: Sarcoptes scabiei


1
Sarcoptes scabiei
  • Jeffery Cote
  • Biology 4800
  • March 18, 2011

2
Cause of Scabies and Mange
  • First identified by Aristotle
  • 1868, formal discovery of scabies causative agent
  • Ectoparasite
  • Class Arachnia
  • Family Scaroptidae
  • Sarcoptes scabiei var (variety) hominis.
  • Mite, feeds on skin and blood

3
Mite life cycle
  • Eggs Hatch
  • 1st instar, nymphs dig into stratum corneum with
    mandibles, moult after 3-4 days
  • 2nd instar, protonymphs, moult after 2-5 days
  • 3rd instar, tritonymphs, moult after 5-6 days
  • Adult males and females
  • Females moult once more

4
Life cycle continued
  • Females, twice as big as males
  • Female 0.5mm long
  • Male 0.25mm long
  • Larvae have 6 legs, other stages have 8.
  • No respiratory tract
  • Mating occurs after females second adult moult.
  • Female produces approx. 40 eggs after
    fertilization
  • Male dies after fertilization
  • Fewer than 1 of eggs develop into adult mites.
  • Females live in burrow for 30-60 days

5
Transmission
  • Transmission via close sustained contact with
    infected individuals, takes at least 30 min to
    become infected.
  • Most common route in adults is sex, thusly lumped
    in with STDs.
  • Secondary transfer can occur via contact with the
    clothes or towel of an infected person, not
    likely unless individual has crusted scabies.
  • Largely caused by crowding and poor healthcare,
    no link to hygiene.
  • Outbreaks occur in prisons, nursing homes,
    hospitals.

6
Symptoms
  • Itching, Rash
  • Pimple like rash (immune reaction to females
    feeding, tunnelling and crapping).
  • Severe itching at night
  • Itching can occur in one or more areas.
  • Scratching can lead to bacterial infection by
    Staph. Aureus or Streptococcus

7
Scabies rash
8
(No Transcript)
9
Crusted Scabies (Norwegian Scabies)
  • Normal infection 12-15 mites
  • Crusted infection millions of mites
  • Immunocompromised patients, elderly, and
    paralyzed (unable to itch or scratch).
  • 45 of cases have advanced AIDS.
  • Vesicles and thick crusts over skin.
  • Very contagious and hard to treat.

10
Crusted scabies on feet
11
Mange
  • Caused by other varieties of Sarcoptes scabiei in
    some cases.
  • Sarcoptic mange affects dogs, wolves, coyotes,
    red foxes, pigs, dogs, horses, and cattle.
  • Intense itching and hair loss.
  • Sarcoptes scabiei are host specific, wont
    survive long on improper host.
  • Mice and cats afflicted by different genera
    Notoedres

12
Mange
13
Treatment
  • Acaricides (substances that kill mites)
  • Scabicides (substances that kill scabies mites)
  • Topical creams
  • 5 permethrin, 1 lindane, 0.05 malathion, 10
    crotamiton, 25 benzyl benzoate.
  • Applied for 8-12 hours, then removed
  • Oral medication
  • Ivermectin (200µg/kg)
  • Animal treatment
  • Ivermectin or insecticides

14
References
  • Elmer, N., N. Glenn, S. Gerhard, and M. Austin.
    1989. Parasitology The Biology of animal
    Parasites. Sixth edition. Lea and Febiger,
    Philadelphia.
  • Karthikeyan, K. 2009. Crusted scabies. Indian
    Journal of Dermatology Venereology Leprology
    75340-347.
  • Tjioe, M. and W. Vissers. 2008. Scabies outbreaks
    in nursing homes for the elderly. Drugs Aging
    25299-306.
  • Walton, S. F. 2010. The immunology of
    susceptibility and resistance to scabies.
    Parasite Immunology 32532-540.
  • Walton, S. F. and B. J. Currie. 2007. Problems in
    diagnosing scabies, a global disease in human and
    animal populations. Clinical Microbiology Reviews
    20268-.
  • Walton, S. F., S. Pizzutto, A. Slender, L.
    Viberg, D. Holt, B. J. Hales, D. J. Kemp, B. J.
    Currie, J. M. Rolland, and R. O'Hehir. 2010.
    Increased Allergic Immune Response to Sarcoptes
    scabiei Antigens in Crusted versus Ordinary
    Scabies. Clinical and Vaccine Immunology
    171428-1438.
  •  
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