Nationwide seroprevalence study of hepatitis B and hepatitis C viruses among blood donors in Paraguay.

Hepatitis B virus (HBV) and Hepatitis C virus (HCV) remain major global health challenges, together accounting for approximately 1.1 million deaths annually and representing leading causes of chronic liver disease, cirrhosis, and hepatocellular carcinoma. In Paraguay, the true burden remains poorly defined, hindering effective public health planning toward the WHO's 2030 elimination goal. This cross-sectional study aimed to establish a comprehensive, nationally representative epidemiological baseline among blood donors. We prospectively analyzed 85,811 blood donor samples. Screening involved chemiluminescent immunoassays for anti-HBc, HBsAg, and anti-HCV, followed by confirmatory Nucleic Acid Amplification Testing (NAT) for HBV-DNA and HCV-RNA. The age-standardized seroprevalences were: 1.66% for anti-HBc, 0.079% for HBsAg, and 0.261% for anti-HCV. However, significant regional variations were noted, with anti-HBc prevalence ranging from 0.70% to 3.86% (p < 0.001). Anti-HBc also increased with age (0.27% in < 20 years to 3.10% in > 50 years). Critically, no HBV markers were detected in donors born after the national 2003 vaccination program. Only 1 of 229 anti-HCV reactive samples was HCV-RNA detectable. While low overall seroprevalence confirms blood safety standards, pronounced regional disparities require targeted public health interventions focused on specific epidemiological hotspots. The absence of HBV markers in the post-vaccination cohort provides strong evidence of the national immunization program's success, offering an invaluable baseline for future elimination strategies.