Zoonotic hepatitis E: animal reservoirs and emerging risks

Hepatitis E virus (HEV) causes acute hepatitis in humans, with distinct patterns in endemic and non-endemic regions. In endemic areas, large outbreaks linked to contaminated water are well documented. In non-endemic regions, sporadic cases are more common, but transmission routes remain unclear. HEV belongs to the Hepeviridae family and includes four main mammalian genotypes and one avian genotype. Unlike other hepatitis viruses, HEV has an animal reservoir. Swine and other mammals infected with HEV typically show no symptoms, while chickens infected with avian HEV may develop a specific disease. Genotypes 1 and 2 are exclusive to humans, while genotypes 3 and 4 infect both humans and mammals. Transmission between animals and humans has been observed for genotypes 3 and 4. Despite this, the origins of many HEV infections remain unknown.

This study aims to clarify the role of animal reservoirs in HEV transmission and identify the sources of infection in non-endemic regions. Understanding how HEV spreads from animals to humans is essential for preventing outbreaks. The study focuses on genotypes 3 and 4, which are known to infect both humans and animals. It also examines the risk factors for HEV infection in individuals with direct animal contact. The goal is to determine how HEV spreads in non-endemic areas where waterborne transmission is less likely. The study highlights the importance of zoonotic transmission in HEV epidemiology. It seeks to provide insights into the mechanisms of cross-species infections. The findings may help improve surveillance and prevention strategies for HEV.

The study reviews existing literature on HEV genotypes and their transmission patterns. It analyzes epidemiological data from endemic and non-endemic regions. The researchers examine case reports and outbreaks to identify transmission routes. They also consider experimental studies demonstrating cross-species infections. The study evaluates the role of swine and other mammals as HEV reservoirs. It investigates the clinical outcomes of HEV infections in different species. The researchers assess the risk factors for HEV transmission in humans. The study synthesizes findings from virological, epidemiological, and clinical research.

HEV genotypes 3 and 4 are found in both humans and mammals, suggesting zoonotic transmission. Experimental studies confirm cross-species infections with these genotypes. Individuals with direct contact with animals are at higher risk of HEV infection. Avian HEV can cause Hepatitis-Splenomegaly syndrome in chickens. Genotypes 1 and 2 are exclusive to humans, with no evidence of animal reservoirs. In non-endemic regions, sporadic HEV cases are often linked to animal exposure. The study identifies swine as a significant reservoir for HEV genotypes 3 and 4. Despite these findings, the sources of some HEV infections remain unidentified.

The study concludes that animal reservoirs play a key role in HEV transmission, especially for genotypes 3 and 4. Cross-species infections have been experimentally confirmed, supporting zoonotic transmission. The study highlights the need for better surveillance of HEV in animal populations. It suggests that direct contact with animals increases the risk of HEV infection in humans. The findings support the importance of zoonotic transmission in non-endemic regions. The study notes that not all sources of HEV infection have been identified. It emphasizes the need for further research to clarify transmission routes. The authors propose that understanding animal reservoirs is crucial for controlling HEV outbreaks.