Background and importance Ivermectin is used as a therapeutic alternative for permethrin-resistant scabies. The recommended treatment consists of administering two single doses (SD) separated by 7–14 days. An increased incidence and resistance to permethrin was observed in late 2020 possibly influenced by the SARS-CoV-2 pandemic.
Aim and objectives To assess the effectiveness of oral ivermectin as a treatment for topical 5% permethrin-resistant scabies in patients from a tertiary hospital and to analyse the characteristics of the sample and the treatment.
Material and methods An observational, retrospective and descriptive study was done including patients who collected ivermectin 3 mg tablets in the Hospital Outpatient Pharmaceutical Care Unit between April 2020 and April 2021. All patients were previously treated with topical 5% permethrin and treatment had failed. Ivermectin was considered effective in patients who were discharged from Dermatology Clinics or did not consult for itching or other symptoms in the following 4 weeks after the last dose. Other variables were: number of doses, age, sex and familiar history or cohabiting cases of scabies.
Results A total of 37 patients were included and 39 applications were made. There were 16 applications from April 2020 to December 2020 (mean of 1.78±1.79 applications/month; 95% CI 0.41 to 3.05) and 23 from January to April 2021 (mean of 4.6±2.6 applications/month; 95% CI 1.37 to 7.83). Ivermectin was effective in 87.2% (34/39) patients and in the remaining 12.8% (5/39) therapeutic failure occurred, so they required treatment for a second time. A patient was excluded because it was unclear if treatment had been ineffective or reinfestation had occurred. 56.4% (22/39) of patients received two SD separated for 7–14 days. 58.5% (24/39) of patients were women and the mean age of the sample was 31.1±19.3 years (95% CI 26.8 to 37.4). 54.0% (21/39) of the patients were aged between 11 and 30 years, and 74.4% (29/39) had a familiar history or cohabitants within their family nucleus with scabies.
Conclusion and relevance In our sample, ivermectin effectiveness was greater than 90% in scabies resistant to topical 5% permethrin and seems independent of the number of doses received. Results suggest that scabies mainly affects women and young people. Infections in cohabitants seem to have an increased frequency and may have been influenced by confinement and delays of treatments during the SARS-CoV-2 pandemic.
Conflict of interest No conflict of interest