Serological and molecular characterization of hepatitis E virus and co-infections during the 2014 Biratnagar outbreak...

Hepatitis E virus (HEV) is a leading cause of acute viral hepatitis in South Asia, frequently causing waterborne outbreaks. Despite the recognized past and potential future epidemic burden in Nepal, data on the serological and molecular characteristics of, and co-infections with, Hepatitis A, B, and C viruses remain scarce. This study aimed to perform a detailed virological and serological characterization of a 2014 outbreak in Biratnagar, Nepal, to define the etiology and evaluate diagnostic patterns.

In this cross-sectional study, 211 patients with suspected acute viral hepatitis were enrolled from three hospitals in Biratnagar, Nepal, during the outbreak peak (April-May 2014). Serum samples were tested for HEV RNA (qRT-PCR), antigen, IgM, and IgG (ELISA), alongside HAV IgM, HBV core antibody, and HCV antibody. Concordance between HEV markers was assessed using Cohen's κ, associations with co-infections via Fisher's exact tests, and clinical correlates with Mann-Whitney U tests.

HEV marker positivity among the 211 patients was as follows: HEV RNA was detected in 12 patients (5.7%), HEV antigen in 29 patients (13.7%), and HEV IgM in 36 patients (17.1%), indicating acute or recent infection. HEV IgG, reflecting past or recent exposure, was detected in 62 patients (29.4%). All successfully sequenced HEV RNA-positive isolates were identified as genotype 1a, consistent with the predominant HEV genotype reported in Nepal. In contrast, HAV, HBV, and HCV infections were infrequent, each accounting for less than 3% of cases, and no significant co-infections were observed. Concordance between HEV markers was variable, supporting the utility of a combined molecular and serological diagnostic approach to capture infections at different stages.

This study provides a detailed characterization of HEV markers during the 2014 Biratnagar outbreak and confirms the circulation of HEV genotype 1a. HAV, HBV, and HCV infections were uncommon, with no significant co-infections observed. These findings offer valuable insights into HEV marker distribution and co-infection patterns, which can inform public health strategies, including enhanced surveillance, improved access to safe water, and consideration of targeted vaccination to mitigate future outbreaks in endemic settings.