Hepatitis of unknown etiology in children in Brazil: A new challenge or the usual scenario ?

BACKGROUND: An outbreak of acute hepatitis of unknown etiology in children was recently reported worldwide. We aimed to describe the burden of hospitalizations due to hepatitis of unknown etiology in children/adolescents in Brazilian public hospitals. METHODS: We retrieved a database of all hospitalizations in the Brazilian Unified Health System (SUS) from January/2019 to February/2022 using the “microdatasus” R package. Hepatitis of unknown etiology was defined by the following International Classification of Diseases [ICD-10] codes: B19, B19.0, B19.9, K72.0, K72.9, K75, K75.9, R94.5, or R93.2. The incidence rates (95% confidence interval, IC) per 1,000 all-cause hospitalizations in different age strata [< 6 years; 6–11 years and 12–17 years] were estimated. RESULTS: A total of 94,198 hospitalizations due to hepatic or infectious diseases with potential liver injury were analyzed. Of them, 1,535 children/adolescents [48.2% male sex, 41.6% aged < 6 years] were hospitalized with hepatitis with unknown etiology. The top ICD-10 codes were B19.9 [unspecified viral hepatitis without hepatic coma; 39.9% (n = 612)], K72.9 [hepatic failure, unspecified; 29.8% (n = 457)], and K72.0 [hepatic failure, not elsewhere classified; 14.5% (n = 223)]. A total of 8.5% (n = 131) of individuals required liver transplantation and 7.0% (n = 107) died during the hospital-stay. In 2021, the incidence rates (95% CI) of hospitalizations for hepatitis with unknown etiology were 7.80 (7.63–7.98), 17.96 (17.46–18.48) and 13.28 (12.95–13.62) per 1,000 all-cause hospitalizations in subjects aged < 6 years, 6–11 years and 12–17 years-old, respectively. Similarly, the incidence rates of hospitalization due to hepatitis with unknown etiology per 1,000 all-cause hospitalizations (CI95%) in January-February/2022 were 7.52 (7.11–7.94), 16.82 (15.68–18.03), and 13.96 (13.10–14.85) for children/adolescents with age < 6 years, 6–11 years, and 12–17 years, respectively. CONCLUSIONS: A non-negligible number of hospitalizations due to hepatitis with unknown etiology in children/adolescents was observed in the last years in Brazil. Up to 15% of those cases needed liver transplantation or died.