scabies
SCABIES
Scabies is a contagious disease caused by the mite Sarcoptes scabiei var hominis.
The affected individual usually complains of having a highly pruritic rash that occurs at night.
It occurs more often in children <15 years of age, sexually active young adults, the immunocompromised and in persons living in crowded living conditions (eg nursing homes, military barracks).
Transmission is typically by direct skin contact with an infected person and in adults, sexual transmission is common.

Introduction

  • Diagnosis is made based on clinical presentation and can be confirmed by microscopic identification of mites, eggs or mite feces
  • Scabies should be suspected in a patient who presents with a highly pruritic rash with nocturnal predominance
    • Scabies is highly suggested if there is also a history of contact with an infected person or if there is a history of contact with family member or sexual partner who has pruritic lesions with nocturnal predominance
  • Scabies is caused by the mite: Sarcoptes scabiei var hominis
  • Occurs more often in children <15 years, sexually active young adults, the immunocompromised and in persons living in crowded living conditions (eg nursing homes, military barracks)
  • Transmission is typically by direct skin contact with an infected person and in adults, sexual transmission is common
    • Though there is limited documentation, transmission by fomites may be possible (especially in cases of crusted scabies where a large amount of parasites are involved)
    • The mites can live for up to 30 days on a host and remain alive for 3 days on furniture, bedding, etc

Signs and Symptoms

  • Primary symptom is generalized pruritus, which is usually worse at night
    • Pruritus is caused by a delayed (type IV) hypersensitivity reaction to the mite and its products (saliva, eggs and feces) once the host becomes sensitized
    • Hypersensitivity occurs 3-6 weeks after infestation but occurs in 1-3 days with re-infestation because the host has been previously sensitized
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