Scabies Signs and Symptoms
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