Mite Infestation of the Skin

These intensely pruritic lesions in the web spaces of the hands and on the naval of a young girl were the result of a scabies infestation.

Patients with scabies present with itchy, erythematous papules or vesicles often in curvilinear patterns in the web spaces of the hands and feet or in the flexor surfaces of wrists and elbows, the belt line, buttocks, and genital areas.¹ The lesions are caused by pregnant mites (Sarcoptes scabiei) that burrow into the skin and lay eggs. Because the mite infestation is transmissible to close contacts, a history of multiple family members with a common itchy rash is a red flag for scabies.

Standard treatment in the United States is 5% permethrin cream, which is applied to the entire body, with the exception of the head and neck, as 2 applications, 1 week apart. Ivermectin, 200 µg/kg, is an effective single-dose oral treatment for scabies; however, it has not been studied in small children.^1,2

Advise patients that the pruritus may last up to 6 weeks after therapy, despite mite eradication, and provide adjunctive antipruritic therapy.¹ Otherwise, patients may return with complaints of recurrent scabies infestation because of continued itching. Persistent pruritus results from an immune reaction to mite proteins, eggs, and feces in the skin.

References:

REFERENCES:1. Johnston G, Sladden M. Scabies: diagnoses and treatment. BMJ. 2005;331:619-622.
2. Meinking TL, Taplin D, Hermida JL, et al. The treatment of scabies with ivermectin. N Engl J Med.1995;333:26-30.