Integrated Surveillance of Hepatitis E Virus (HEV) in Diffa Health District, Niger

The hepatitis E virus (HEV) is a major public health concern in Niger, where the infection is considered endemic, with sporadic cases reported throughout the year and an outbreak documented in 2017 in the Diffa region, in the south-east of the country. The Diffa region is particularly affected (2,3) due to limited access to safe drinking water and sanitation facilities, the presence of large populations of internally displaced persons (IDPs) and refugees, and difficulties in ensuring continuous health services in humanitarian settings. Historically, the HEV outbreak in Diffa has been associated with high morbidity and mortality, with pregnant women being disproportionately affected and experiencing higher case fatality rates (2,3). These factors highlight the urgent need to strengthen surveillance and early detection of HEV transmission among vulnerable populations. To date, EHV surveillance in Niger has been primarily reactive and case-based. Suspected cases are identified when patients present with acute jaundice and fever, and laboratory confirmation relies on limited diagnostic capacity at central facilities. This system tends to detect outbreaks late, once transmission is already well established and response options are limited. Furthermore, with the exception of poliovirus surveillance (4), there is no systematic environmental surveillance system for HEV in Niger, leaving a critical gap in the ability to monitor transmission dynamics at community level. Wastewater and environmental surveillance (WES) has established itself as a powerful tool for monitoring infectious diseases (5,6). It has been successfully implemented as part of poliovirus eradication programmes and was adapted globally during the COVID-19 pandemic for the detection of SARS-CoV-2 (7,8). WES provides a population-level signal that is independent of healthcare utilisation and often enables the detection of viral circulation before there is an increase in clinically reported cases. Building on the existing infrastructure for environmental surveillance of poliovirus in Diffa (4), this project aims to adapt and validate WES methods for HEV.

Purpose

This project integrates environmental, clinical, and epidemiological approaches within an integrated surveillance framework to strengthen early detection of HEV in the Diffa Health District. By combining wastewater and environmental surveillance (WES) with enhanced case-based testing and genomic sequencing, the project will generate high-resolution data linking community-level viral circulation to laboratory-confirmed clinical cases.oratoire.