Caused by infestation with Sarcoptes scabiei, a 0.3- to 0.5-mm mite that can burrow and deposit eggs in the human stratum corneum.
Transmission usually occurs via direct skin-to-skin contact, seen most commonly in overcrowded living conditions.
Clinical features include pruritus, erythematous papules, and linear burrows in the interdigital web space and red nodules on the penis, with patients often reporting history of exposure to an infested individual.
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 mite under 10× power
From the personal collection of Laura Ferris, MD, PhD
- infants, children, and the elderly
- hx of overcrowding
- hx 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
- thick, crusted lesions occurring on elbows, knees, hands, and feet with dystrophic nails
- papules on face, neck, palms, and soles in children
1st Tests To Order
- ectoparasite prep
Other Tests to Consider
- skin biopsy
- epiluminescence light microscopy
nonpregnant/nonlactating adults or children over 5 years
- noncrusted scabies
- permethrin or ivermectin
- malathion or benzyl benzoate
- crusted (Norwegian) scabies
- combination therapy with permethrin or benzyl benzoate plus ivermectin
infants and children 2 months to 5 years and pregnant or lactating females
- precipitated sulfur compounds 10% to 25%
infants under 2 months
- precipitated sulfur 6% in petroleum