The efficacy of mass drug administration strategies to control scabies in a highly endemic population.

This community intervention trial is a prospective comparison of efficacy and safety of 3 different treatment regimens for scabies. Two of the regimens involve Mass Drug Administration (MDA) and the third is standard of care treatment of symptomatic people and their household contacts. Each of the treatment regimens has beenrandomly assigned to the population of 1 of 3 separate island groups, by a person independent form the investigator. After 100% of the sample is reviewed at the initial study visit, study outcomes and adverse events will be assessed at 3 months (analysing 20% of sample), 12 months (entire sample, 100%), and 24 months (20% of sample), with 12 months being the primary endpoint. Interventions: Each one of the islands will be assigned to one of the following intervention arms. Assignment will be random, but we note that the study is not formally designed as a randomised trial. In all 3 arms, all residents will be invited to participate, and a skin examination will be undertaken at the initial study visit in those who consent to participate. 1. Oral ivermectin based MDA: Participants will be offered 1 dose of oral ivermectin at 200 ug/kg, unless contra-indicated (as follows). Ivermectin will be replaced by topical permethrin 5% cream in the following “ivermectin contra-indication” groups: children under 15 kg, pregnant and breastfeeding women (as according to onchocerciasis guidelines), people with neurologic disease such as Parkinson’s Disease or cerebral palsy, and people taking medication that is metabolised by the cytochrome p450 pathway. We estimate the number excluded from the ivermectin group to be approximately 20% of the population (10% being children under 15kg and 10% due to pregnancy, lactation or other contraindication); we will deal with this in our analysis by using an intention to treat approach. At 1 week, those in whom clinical scabies, itch or rash was observed at the initial visit will be offered a 2nd dose of the same treatment that they received at the initial visit. 2. MDA of topical permethrin 5%: Participants will be offered a dose of topical permethrin cream 5%, followed by a 2nd dose at 1 week for those in whom clinical scabies, itch or rash was observed at the initial visit. 3. Standard of care: Those found to have scabies will be referred to the local health care worker for treatment according to the Fiji IMCI guidelines which advise a single application of permethrin 5% for those with scabies and for their families, and a 2nd dose at 2 weeks if symptoms and signs of scabies persist. Administration of scabies treatment: Participants assigned to permethrin 5%(either as part of MDA or for clinical reasons) will receive a tube of cream and will be asked to apply the cream from neck to toes, and leave it on for a minimum 8 hours and a maximum of 24 hours. For children aged less than 5 years, parents will be asked to apply cream as a directly observed therapy before they leave the clinic. Older children and adults will be able to apply their treatment at home. For participants assigned to ivermectin, the dose will be determined according to body weight and treatment will be administered under supervision before participants leave the clinic. Participants with very severe or crusted scabies (so-called “Norwegian scabies”) will be treated with 2 doses of ivermectin (except if ivermectin is contraindicated as outlined above) with a second dose being administered at 7 to 14 days, in conjunction with twice weekly permethrin cream for 1 month. In cases where ivermectin is contraindicated, in people with crusted scabies, ivermectin will replaced by two doses of permethrin cream 5%, one at baseline and one at 7 to 14 days, with review at 1, 2, 3,12 and 24 months. The trained study nurse will administered the second dose of treatment to crusted scabies participants and will follow up on adherence weekly and communicate with the study coordinator.