Scabies is highly contagious via direct skin-to-skin contact. It is most common in overcrowded living conditions and in developing countries.
Caused by Sarcoptes scabiei, a 0.3- to 0.5-mm mite that can burrow and deposit eggs in the human stratum corneum.
Microscopic visualization of mites, their eggs, or feces in skin scrapings is helpful but not essential to initiation of treatment.
Most popular treatment options include topical permethrin and oral ivermectin.
Primarily considered a nuisance in the developed world. Children in the developing world can contract secondary streptococcal infection in their skin lesions, with potential complications of rheumatic heart disease or poststreptococcal glomerulonephritis.
Scabies is caused by infestation with the ectoparasite Sarcoptes scabiei, a mite that burrows through the human stratum corneum. Spread is primarily via direct contact with an individual with scabies. Clinical clues to diagnosis include intense pruritus and linear erythematous burrows, particularly on the extremities, or erythematous papules and nodules elsewhere such as in the axilla or genital area. Rarely, it can present on the neck and scalp. Diagnosis is based on history and clinical appearance.
History and exam
Key diagnostic factors
- infants, children, and older adults
- history of overcrowding
- history of itching in family members or close contacts over the same period
- generalized and intense pruritus, typically worse at night
- papules, vesicles, excoriations
- positive ink burrow test
Other diagnostic factors
- papules on face, neck, palms, and soles in children
- thick, crusted lesions occurring on elbows, knees, hands, and feet with dystrophic nails
- overcrowded living conditions/poverty
- living in close quarters with others who are infected
- age under 15 or over 65 years
- sexual contact with new or multiple partners
- poor hygiene
- contact with an infected animal
- contact with contaminated clothing, towels, and bedding
- winter season
1st investigations to order
- ectoparasite prep
Investigations to consider
- skin biopsy
- epiluminescence light microscopy
nonpregnant/nonlactating adults or children over 5 years
infants and children 2 months to 5 years and pregnant or lactating females
infants under 2 months
Ryan Harris, MD
Treasure Valley Dermatology and Skin Cancer Center
RH declares that he has no competing interests.
Dr Ryan Harris would like to gratefully acknowledge Dr Pooja Khera and Dr Laura Korb Ferris, previous contributors to this topic.
PK and LKF declare that they have no competing interests.
David Cassarino, MD, PhD
Department of Pathology and Laboratory Medicine
University of California
DC declares that he has no competing interests.
Roderick J. Hay, DM, FRCP, FRCPath, FMedSci
International Foundation of Dermatology
RJH declares that he has no competing interests.
- Xerotic dermatitis
- Sexually transmitted infections treatment guidelines, 2021: ectoparasitic infections
- European guideline for the management of scabies
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