More About Scabies

John F. Rupp, MD

,
David L. Kaplan, MD

Persistent, unremitting itch-which intensifies at night-is the chief complaint of patients with scabies. The female Sarcoptes scabiei mite (A) burrows into the stratum corneum, where she lays eggs. The parasite is transferred by intimate contact and fomites, such as infested clothing, towels, and bedding.

Persistent, unremitting itch-which intensifies at night-is the chief complaint of patients with scabies. The female Sarcoptes scabiei mite (A) burrows into the stratum corneum, where she lays eggs. The parasite is transferred by intimate contact and fomites, such as infested clothing, towels, and bedding.

Small erythematous papules develop on most patients between 4 and 6 weeks after exposure. Typically affected sites include finger webs, wrists, waistline, nipples, and penis (seen here with a “Prince Albert” penile ring)1(B).

To identify the organism, locate a papule or burrow that has not been excoriated. Obtain scrapings from the lesion; a microscopic examination will reveal the mite or its eggs.

Norwegian, or crusted, scabies may be seen in immunocompromised patients (C and D). The lesions have an eczematous or psoriatic appearance that is thought to be precipitated by the altered immune response.

A common complication of scabies is secondary bacterial infection induced by scratching. Consider scabies as a possible cause of widespread impetigo or folliculitis.

Topical permethrin is the treatment of choice; a single application is effective in more than 90% of cases. To prevent reinfestation, the entire body must be treated; family members, intimate contacts, and fomites must be treated as well. Most treatment failures can be attributed to inadequate eradication of all sources of the mite rather than to ineffective medication.

REFERENCE:1. Higgins SP, Estcourt CS, Bhattacharyya MN. Urethral rupture in a homosexual male following avulsion of a 'Prince Albert' penile ring. Int J STD AIDS. 1995;6:54-55.