Effectiveness of oral ivermectin for eradicating infesting mites in patients of scabies

Objective To evaluate the effectiveness of single and two doses of oral ivermectin in scabies by observing its effect on infesting Sarcoptes scabiei. Patients and methods This quasi experimental study, after approval of the hospital ethical committee, was conducted at the Skin Centre, Military Hospital, Rawalpindi, from September 2009 to August 2010. Fifty patients with scabies of up to two month duration having at least ten burrows/papules/nodules each with a visible mite were included in the study. Patients with other concomitant illnesses, pregnancy, lactation and those who had been treated with antiscabies medicines in the previous two months were excluded. Patients with more than six household contacts were also excluded from the study. Patients were given oral ivermectin 200μg/kg (Mectis®). Patients were followed up after a week and previously identified lesions were explored for a living mite. If a living mite was extracted from a lesion, the patient was prescribed another dose of oral ivermectin. At second follow up after a week, demonstration of living mites was considered as treatment failure and the patient was prescribed 5% permethrin cream for topical application. Final review of patients was carried out at the end of fourth week. Results Out of 50, in 22 (44%) patients, a living mite was isolated at one week follow up. At the end of second week, a living Sarcoptes scabiei was found in 11 (22%) patients. All of these 11 nonresponders were treated with topical application of 5% permethrin lotion. At the end of four weeks 49 patients reported for follow up without any identifiable living mite. One patient who had no mite at the end of first and second week did not report back after four weeks. Conclusion Oral ivermectin is a convenient remedy for scabies with a cure rate of 56 % after a single dose and 78% after two doses, a week apart.