Scabies

Definition

A contagious, intensely pruritic human skin disease caused by infestation with the itch mite *Sarcoptes scabiei* var. *hominis* (Arachnida: Sarcoptiformes: Sarcoptidae). The female mite excavates epidermal burrows to lay eggs, triggering a hypersensitivity reaction that produces papules, vesicles, and linear burrow tracks, typically on finger webs, wrists, axillae, and genitalia. Transmission occurs primarily via prolonged skin-to-skin contact; fomite spread is less common. Secondary bacterial infection frequently complicates excoriated lesions. In veterinary contexts, related *Sarcoptes* varieties cause sarcoptic mange in domestic and wild mammals.

Etymology

From Latin *scabere*, 'to scratch', referring to the characteristic intense pruritus.

Example

In a refugee-camp outbreak, entomologists confirmed *Sarcoptes scabiei* by skin scraping microscopy and implemented mass drug administration with permethrin to interrupt transmission.

Synonyms

• the itch
• seven-year itch (historical)
• sarcoptic mange (when referring to animal variants)

Related Terms

• Sarcoptes scabiei
• sarcoptic mange
• acariasis
• Ectoparasite
• hypersensitivity reaction
• pruritus
• epidermal burrow
• skin scraping
• permethrin
• ivermectin

Usage Notes

Distinguish from 'scabies' as a genus of freshwater mussels (Bivalvia: Unionidae) or fungal/plant pathogen names—homonyms unrelated to the medical condition. In clinical and entomological literature, 'scabies' without qualification refers exclusively to the human disease. Animal infestations are properly termed 'sarcoptic mange' to avoid ambiguity. Diagnosis requires demonstration of mites, eggs, or fecal pellets (scybala) in epidermal scrapings, though experienced clinicians may diagnose clinically in classic presentations. The 2–6 week incubation for primary infestation reflects sensitization time; re-infestation produces symptoms within 24–48 hours due to established hypersensitivity.