Scabies Management Outcomes: Identification of Risk Factors for Treatment Success or Failure.

Introduction: Scabies is a parasitic infectious skin disease classified as a neglected tropical disease by the World Health Organization in 2017. Currently, it is becoming a major challenge in high-income countries, with rapidly rising incidence and increasing reports about treatment failure.

Objectives: Factors that are associated with treatment failure or success were evaluated.

Methods: This non-interventional prospective observational study was conducted as a questionnaire survey at the Department of Dermatology and Venereology of the University of Freiburg from January to November 2023. Patients that still suffered from scabies 2-6 weeks after medical treatment were classified as "failure"; those who were free of scabies belonged to the success group.

Results: Of 102 participants, with a mean age of 34.4 ± 17.3 years (male: 60.4%), 77 (75.5%) were assigned to the success and 25 (24.5%) to the failure group. A larger proportion of the latter was clinically more severely affected, applied permethrin monotherapy, did not undertake special decontamination measures, but used alcohol as a disinfectant. Treatment success was associated with an additional systemic treatment, a repeated intake of ivermectin, and intensified decontamination measures such as storage of clothes in plastic bags for four days or vacuum cleaning of car seats.

Conclusions: Our findings indicate that a consistent second-dose administration of ivermectin and refraining from permethrin monotherapy may be advisable.