Simplified Treatment Regimen as a Decisive Strategy for Controlling a Scabies Outbreak in a Prison: Benzyl Benzoate vs. Permethrin

Scabies, caused by the mite Sarcoptes scabiei , is a highly transmissible parasitic dermatosis, especially in overcrowded environments such as prisons, where precarious structural conditions favor prolonged and difficult-to-control outbreaks. In Brazil, the prison context is marked by vulnerabilities that amplify the spread of infectious diseases. This study aimed to evaluate the effectiveness and treatment adherence for scabies in a prison, comparing the use of Benzyl Benzoate (BB) soap with 5% Permethrin lotion, both associated with Ivermectin. Prospective observational study conducted between February and May 2024 in a male prison with a population of 347 incarcerated individuals (IPL). The diagnosis of scabies was clinical, based on physical examination and individual interviews with standardized questionnaires. Initially, all IPL received 5% permethrin lotion combined with Ivermectin, following recommended dosing. Due to a high rate of therapeutic failure, an analysis of adherence barriers was performed, followed by replacement of the regimen with BB soap plus a new dose of ivermectin. The primary outcome was complete resolution of lesions and pruritus within 14 days after treatment. Among the 97% of IPL affected by scabies, 91% exhibited initial therapeutic failure associated with poor adherence to the permethrin regimen, driven by low educational level, lack of temporal markers (clocks/calendars), and adverse structural conditions (overcrowding, excessive heat, and poor ventilation). After introducing BB soap, 70% of IPL experienced clinical resolution after a single use, 24% after a second use, and only 6% remained symptomatic, requiring addition of permethrin. The outbreak was controlled within 28 days after the therapeutic change, with no new cases reported after May 2024. The simplified dosing regimen using BB soap combined with Ivermectin proved more effective in controlling the scabies outbreak in a prison setting, primarily due to ease of use and improved adherence compared with permethrin lotion. Selecting therapeutic regimens adapted to the social and structural realities of vulnerable populations is essential for rapid and effective control of infectious disease outbreaks in high-density environments such as prisons.