Understanding the Serologic and Molecular Epidemiology of Hepatitis A Infection in Puducherry and Surrounding Regions of India.

Hepatitis A virus (HAV), traditionally a paediatric illness in endemic regions, is now exhibiting an emerging age shift in symptomatic cases. This study investigates the sero-molecular epidemiology of Hepatitis A in Puducherry and surrounding regions. Between January and November 2024, 513 acute viral hepatitis cases were evaluated for serum IgM anti-HAV. Representative samples underwent sequencing and B-cell epitope analysis. Of the 150 patients (29.23%) tested positive for HAV, children under 12 years (50%) were most affected, with an increasing trend in adult infection (31.33%), while adolescents aged 12-17 years accounted for 18.66%. All viral strains were genotype IIIA with no major B-cell epitope changes. A total of 732 asymptomatic individuals (2023-2024) were screened for IgG anti-HAV across different age strata (1-5, 6-10, 11-15, 16-20 and 21-30 years). The seroprevalence of HAV IgG varied by age: 1-5 years (58.5%), 6-10 years (52.87%), 11-15 years (44.95%), 16-20 years (56.88%) and 21-30 years (83.16%). Hepatitis A remains a significant health concern in Puducherry and its surrounding regions, with symptomatic infections occurring more frequently in children, followed by adults. However, HAV seroprevalence was higher in young adults and comparatively lower in children and adolescents.