Ivermectin for Sarcoptes scabiei hyperinfestation

Crusted (Norwegian) scabies is an unusual variant of scabies caused by hyperinfestation with Sarcoptes scabiei. It has high morbidity, and secondary bacterial skin sepsis may result in life-threatening bacteremia. An open label study of oral ivermectin was carried out in patients with crusted scabies refractory to topical therapy.Patients with refractory crusted scabies were prescribed oral ivermectin, one to three doses of 200 mg/kg at 14-day intervals, combined with topical scabicide and keratolytic therapy.Of the 20 patients who received ivermectin, 8 had a complete initial clinical response, a partial response was achieved in 9, and minimal improvement occurred in 3. Three doses of ivermectin were curative for 8 of 10 cases, but recurrence of scabies from presumed reinfestation occurred in at least half of these.The authors conclude that ivermectin is effective for crusted scabies; however, multiple doses may be required to achieve a cure, and recurrence 6 or more weeks after completing treatment is common.