Single-Center Retrospective Study of Hospitalized Hepatitis A Cases in Southern Bulgaria, 2015-2023

The hepatitis A virus (HAV) infection continues to represent a considerable public health issue in Eastern Europe, particularly in Bulgaria, where incidence rates exceed the EU average. This study sought to investigate the epidemiological and clinical aspects of acute hepatitis A in Southern Bulgaria between 2015 and 2023 and to assess changes during the COVID-19 pandemic period.

A retrospective descriptive-analytic study was conducted among 1810 hospitalized patients with confirmed acute HAV infection at a tertiary infectious diseases center from 2015 to 2023. Demographic, clinical, laboratory, and temporal data were analyzed, comparing the pre-pandemic period (2015-2019) with the pandemic phase (2020-2023).

Most hospitalized cases occurred during the pre-pandemic period (88.0%), with epidemic peaks observed in 2016-2017. Individuals under 18 years comprised 69.9% of cases, with a median age of 9 years and a slight male predominance of 54.9%. A notable seasonal pattern was identified, characterized by peaks in autumn and early winter. Patients hospitalized during the pandemic period were significantly older compared with the pre-pandemic period (median age 14 vs. 8 years, p < 0.001). Adults experienced significantly longer hospitalization and higher ALT, AST, total bilirubin, and direct bilirubin levels compared with pediatric patients (all p < 0.001). The median duration of hospitalization was 7 days (IQR 6-10). Two in-hospital deaths were recorded, corresponding to a case fatality rate of 0.11%.

Hepatitis A in Southern Bulgaria mostly impacts children but exhibits changing epidemiological trends, underscoring the necessity for focused preventative methods, such as vaccination and enhanced surveillance.