Scabies is a parasitic skin infestation caused by the Sarcoptes scabiei var. hominis (S. scabiei) mite, which is primarily transmitted via direct human-to-human contact. The female scabies mite burrows into the superficial skin layer, causing severe pruritus, particularly at night. Primary lesions commonly include erythematous papules, vesicles, or burrows. Treatment involves topical medical therapy (e.g., permethrin) and decontamination of all clothing and textiles.
- Pathogen: Sarcoptes scabiei var. hominis
- Risk factors: crowded living conditions (e.g., institutions such as nursing homes, child care facilities, and prisons) 
- The fertilized, female mite tunnels into the superficial skin layer (stratum corneum), forming burrows in which she lays her eggs and deposits feces (scybala).
- After 2 months, the female parasite dies on site.
- Following a period of 3 weeks, the larvae mature into adult mites, maintaining the infestation cycle.
- The excretions of the mites and their decomposing bodies contain antigens which cause an immunological response (see , presenting as severe pruritus and excoriations.
- Incubation period: approximately 3–6 weeks following infestation.
- Intense pruritus that increases at night 
- Burning sensation
- Skin lesions
- Predilection sites
- Wrists (flexor surface)
- Medial aspect of fingers
- Interdigital folds (hands and feet)
- Male genitalia (e.g., scrotum, penis)
- All other intertriginous areas of the skin (anterior axillary fold, buttocks)
- Areas surrounding the nipple (mamillary region)
- Periumbilical area or waist
- Knees (flexor surface)
- Feet (dorsal and lateral aspect)
- Additionally in children, elderly persons, and immunosuppressed patients: scalp, face, neck, under the nail, palms of hands, and soles of feet
- Typical history and skin lesions on clinical examination (see “Symptoms/clinical findings” above)
- Environmental diagnosis (direct contact with infected persons)
- Detection of mites, larvae, ova, or mite feces
- Pathogen: Cimex lectularius
- Transmission: direct contact with infested furniture, mattresses, bed frames
- Risk factors: crowded, unsanitary living conditions
- Clinical features
- Consult a pest control service
- Detection of bed bugs in the patient's environment confirms the diagnosis
The differential diagnoses listed here are not exhaustive.
Medical therapy: topical application of a scabicidal agent
- Drug of choice: permethrin 5% lotion
- Symptomatic treatment of pruritus
- All close contacts should receive prophylactic treatment.
- Wash all textiles (e.g., clothing and bedding) (day 1 and day 8 post-treatment)
- All contacts within the household should be treated for scabies infestation even if asymptomatic.
We list the most important complications. The selection is not exhaustive.