Time trends in the burden of scabies from 1990 to 2021, and projections to 2050: Insights based on the Global Burden of Disease Study 2021

Background Scabies is a parasitic skin disease known since ancient times, yet it remains a persistent and significant global health challenge in the modern era affecting populations around the world. This study aims to assess the global burden of scabies across all age groups from 1990 to 2021 and predict epidemiological trends up to 2050. Methods The study utilized data from the Global Burden of Disease Study 2021. Data from 204 countries and territories were stratified by sociodemographic index, gender, age. Age-standardized rates per 100,000 population were calculated for prevalence, incidence, and disability-adjusted life years, with 95% uncertainty intervals. Trends were assessed using Joinpoint regression models to compute the annual percent change. A time-series analysis-based prediction model was applied to estimate age-standardized incidence rates up to 2050. Findings In 2021, the global incidence and prevalence of scabies in both sexes were 622.4 million (95% UI 556.2-695) and 206.5 million (95%UI 184.1-231.7) respectively. The age-standardized prevalence rate was 2666.47 per 100,000 population (95% UI: 2368.2–2994.5), and the age-standardized incidence rate was 8049.53 per 100,000 (95% UI: 7165.24–9024.24). The disability-adjusted life years reached 68.72 per 100,000 (95% UI: 38.3–113.2). Joinpoint regression analysis indicated a modest downward trend in age-standardized prevalence rate that did not reach statistical significance (p = 0.411), suggesting limited evidence for global improvement in scabies control. Age-stratified analysis revealed a distinct bimodal age distribution pattern in scabies incidence, the first at ages 5–14 and the second at 20–24, declining after age 25. Frontier analysis demonstrated that middle sociodemographic index regions carried the heaviest scabies burden, with the highest incidence and prevalence rates worldwide. According to the Auto-Regressive Integrated Moving Average time-series model, the global age-standardized incidence rate of scabies is predicted to decline overall by 2050, and these findings indicate that future trends are expected to vary substantially by region. Conclusions Scabies remains a severe public health problem worldwide, and its incidence and disease burden demonstrate significant regional and age-related variations. The age-standardized prevalence rate in most sociodemographic index regions showed a downward trend, reflecting that the incidence of scabies has been controlled to some extent, but the prevalence rate is still very high. However, the future epidemiological trend of scabies has regional heterogeneity, public health interventions should focus on countries and territories in the high-middle sociodemographic index regions and middle sociodemographic index regions, optimizing healthcare resource allocation, improving basic health infrastructure, enhancing health education.