Sarcoptes

Sarcoptes is a genus of small, obligate parasitic mites of the family Sarcoptidae. Species are adapted to dwell in the epidermis of mammals, feeding on skin and producing itch through inflammatory responses. Adults are oval, about 0.3–0.4 mm in length, with a rounded carapace and short legs. The legs bear specialized pedicels and piercing mouthparts; females tunnel under the stratum corneum to lay eggs.

Of the species in this genus, Sarcoptes scabiei is the best known and causes scabies in humans. It also infests a wide range of mammals, with host-adapted varieties occurring in dogs, pigs, cattle, and other animals.

Transmission occurs mainly through prolonged close skin-to-skin contact; fomite transmission is less common. The life cycle takes about 10–14 days to complete and includes egg, larva, and nymph stages before adulthood. Females burrow into the epidermis, laying eggs in tunnels; hatchlings mature into breeding adults, causing intense itching and a vesiculopapular rash, especially in finger webs, wrists, elbows, and genitals.

Diagnosis relies on demonstration of mites, eggs, or fecal pellets in skin scrapings or via dermoscopy; clinical features with pruritus and typical distribution can support diagnosis. Treatment includes topical scabicides such as permethrin cream 5% applied to the entire body and repeated after 1–2 weeks, or oral ivermectin; simultaneous treatment of close contacts and decontamination of clothing and bedding are recommended.

Crusted (Norwegian) scabies is a more severe form occurring in immunocompromised individuals or the elderly. Prevention relies on prompt treatment and minimizing transmission. Taxonomy: S. scabiei is the principal member affecting humans; the genus contains several species parasitizing different hosts.