Hepatitis E virus (HEV) is a major cause of acute viral hepatitis worldwide, with zoonotic genotypes detected in humans and animals. In Africa, limited data exist on environmental HEV circulation. Here, we report the first detection of Rocahepevirus ratti (RHEV) in urban wastewater from Conakry, Guinea. From December 2024 to April 2025, Rocahepevirus ratti (RHEV) has been detected in 35 out of 180 urban untreated wastewater samples in Conakry, Guinea. The phylogenetic analysis of partial HEV ORF1 genome segments reveals clustering with African rodent RHEV strains, highlighting environmental contamination and potential zoonotic risk for human populations in proximity. This finding underscores the need for integrated One Health surveillance to monitor HEV transmission at the human–animal–environment interface in West Africa, particularly in Guinea.

Background: The recent resurgence of measles during the post-COVID-19 period represents a major public health concern worldwide, particularly for low- and middle-income countries (LMIC) like Guinea which has experienced recurrent measles epidemics, characterized by limited clinical surveillance. In this context, our study aimed to use environmental surveillance of wastewater to provide an effective and cost-efficient tool for monitoring measles virus circulation.Methods: In the absence of wastewater treatment plants in Guinea, our study was conducted in the semi-enclosed wastewater drainage networks, informal drainage networks and natural waterways. Measles virus detection in wastewater was performed using a simple, low-cost protocol adapted to LMIC. Measles quantification was normalized relative to the crAssphage signal, a quantitative indicator of the populations being monitored.Results: From August 2024 to October 2025, measles virus was detected in 32% of the wastewater samples analyzed (345/1072) with a clear peak during the early 2025 epidemic. This detection consistent with national clinical surveillance data demonstrates the value of wastewater monitoring as an early warning tool, helping to anticipate the resurgence of measles cases in the population.Interpretation: The modeling of our environmental surveillance adapted to a decentralized surveillance framework proposes an accurate characterization of the spatiotemporal dynamics of measles virus circulation in municipalities of Conakry and allows early alert about outbreaks before detection in health centers. This work demonstrates the feasibility of environmental surveillance in low-resource country settings and proves that it is a relevant tool during epidemic periods, helping to complement and strengthen the national surveillance system.

Background and Aim: Hepatitis E virus (HEV) is an important cause of acute viral hepatitis worldwide and remains a neglected public health concern in sub-Saharan Africa. Although several African studies have reported HEV circulation, no comprehensive synthesis has integrated human, animal, and environmental evidence from West Africa. This study aimed to determine the prevalence, geographic distribution, risk-group characteristics, and genotype diversity of HEV in West Africa using a One Health approach. Materials and Methods: A systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered in PROSPERO (CRD420251178069). PubMed, ScienceDirect, Google Scholar, and reference lists were searched for studies published between 1997 and August 2025. Studies involving humans, animals, and environmental samples from West African countries were included. Data extraction and quality assessment were performed independently by two reviewers. A random-effects meta-analysis using Comprehensive Meta-Analysis software version 3.0 was conducted to estimate the pooled prevalence and investigate heterogeneity. Human populations were stratified into low- and high-risk groups according to exposure characteristics. Results: Ninety-six eligible studies conducted in 12 countries and involving 36,014 individuals were included. A total of 9,465 HEV-positive cases were identified. The pooled overall seroprevalence was 9.7% (95% confidence interval [CI]: 8.2%–11.5%), with substantial heterogeneity (I² = 97.53%). The pooled prevalence of anti-HEV immunoglobulin (Ig)G was 15.7%, ranging from 2.7% in Guinea to 29.3% in Burkina Faso. High-risk populations exhibited higher prevalences of IgG (25.9%), IgM (4.6%), and total antibodies (16.9%) than low-risk groups. Animal reservoirs, particularly pigs, showed high infection frequencies, whereas environmental contamination reached 24% in vegetables. Human genotypes 1e, 2b, 3e, 3f, and 4b, and animal- and environment-associated genotypes 3a and 3c were identified across the region. Conclusion: HEV infection is widely distributed in West Africa, with marked differences among countries and population groups. The coexistence of human, animal, and environmental reservoirs highlights the importance of integrated One Health surveillance and targeted prevention strategies to reduce the regional burden of HEV infection. Keywords: environmental contamination, genotype distribution, hepatitis E virus, meta-analysis, One Health, prevalence, systematic review, West Africa.

Hepatitis E virus (HEV) is a major cause of acute viral hepatitis worldwide, with zoonotic genotypes detected in humans and animals. In Africa, limited data exist on environmental HEV circulation. Here, we report the first detection of Rocahepevirus ratti (RHEV) in urban wastewater from Conakry, Guinea. From December 2024 to April 2025, Rocahepevirus ratti (RHEV) has been detected in 35 out of 180 urban untreated wastewater samples in Conakry, Guinea. Phylogenetic analysis of partial HEV ORF1 genome segments reveals clustering with African rodents RHEV strains, highlighting environmental contamination and potential zoonotic risk for human population in proximity. This finding underscores the need for integrated One Health surveillance to monitor HEV transmission at the human-animal-environment interface in West Africa particularly in Guinea.

The recent resurgence of measles during the post-COVID-19 period represents a major public health concern worldwide, particularly for low- and middle-income countries like Guinea which has experienced recurrent measles epidemics in recent years, characterized by limited clinical surveillance. In this context, environmental surveillance adapted to the constraints of decentralized wastewater management can represent an effective and cost-efficient tool for monitoring measles virus circulation. Following a pilot study conducted in the semi-enclosed wastewater drainage networks of the city center of Conakry (March 2022–April 2024), measles surveillance was expanded to the entire city, including informal networks and natural waterways. From August 2024 to October 2025, measles virus was detected in 32% of the wastewater samples analyzed (345/1072) with a clear peak during the early 2025 epidemic. This detection consistent with national clinical surveillance data demonstrates the value of wastewater monitoring as an early warning tool, helping to anticipate the resurgence of measles cases in the population. The quantification of the measles virus was normalized relative to the crAssphage signal, a quantitative indicator of the density of the populations being monitored. The modeling of our environmental surveillance adapted to a decentralized surveillance framework proposes an accurate characterization of the spatiotemporal dynamics of measles virus circulation in municipalities of Conakry and allows early alert about outbreaks before detection in health centers. This work demonstrates the feasibility of environmental surveillance in low-resource country settings and proves that it is a relevant tool during epidemic periods, helping to complement and strengthen the national surveillance system.

Hepatitis E virus (HEV) belongs to the Hepeviridae family, Orthohepevirinae subfamily, Paslahepevirus genus which includes eight genotypes. HEV genotype 1 (HEV-1) and genotype 2 (HEV-2) are specific to humans, while genotype 3 (HEV-3) and genotype 4 (HEV-4) circulate mainly in pigs, wild boars and deer, but have also a zoonotic potential. HEV genotype 5 (HEV-5) and 6 (HEV-6) viruses circulate in wild boars in Japan and genotype 7 (HEV-7) and 8 (HEV-8) viruses circulate in camelids. The worldwide distribution of HEV is influenced by ecological and socioeconomic factors. In developing countries in Africa, transmission of the virus through fecally contaminated water accounts for a high proportion of epidemics. Direct human-to-human transmission is less frequent, although cases of infection through blood transfusion have been reported in several countries. Thanks to the "One Health" approach, zoonotic transmissions of HEV from pig to human have been more recently observed. These zoonotic infections are mainly due to the handling or consumption of pork meat or contact with pig manure, contaminating the environment. They alert on professions or populations at-risk, such as livestock farmers or butchers. In addition, HEV infection is particularly severe in pregnant women, leading to fetal and maternal death due to acute liver failure. Finally, the development and application of serological or molecular detection tests in Africa indicates that HEV can be incriminated in symptoms without etiology or falsely attributed to other hepatic viruses or to the yellow fever virus. This review updates studies on the epidemiology of HEV in Africa, a crucial step to better understand the virus and develop surveillance strategies to prevent and better control epidemics.