Care for health and stay away from hepatitis E

Understanding of hepatitis E

Hepatitis E is one of the most important viral hepatitis in the world. It is an acute infectious disease caused by hepatitis E virus (HEV), mainly affecting the liver. Viral hepatitis E was formerly known as enterally transmitted non-a, non-B hepatitis. In 1983, Balayan et al. Detected virus particles with a diameter of 27 ~ 30 nm from the feces of an orally infected volunteer by immunoelectron microscopy (IEM), and successfully infected marmosets with the virus, so they considered that the virus was the pathogen of hepatitis E. In 1989, Reyes et al. Obtained the gene clone of this virus by using molecular cloning technology, and formally named this type of hepatitis and its related virus as Hepatitis E and Hepatitis E virus (HEV) respectively.

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Etiology of hepatitis E

Hepatitis E Virus (HEV) is a non-enveloped, positive-strand RNA virus belonging to the genus Hepatitis E virus in the family Hepativiridae. HEV virions are spherical with a diameter of about 32-34 nm and a genome length of about 7.2 to 7.6 kilobase pairs, containing three open reading frames (ORFs): ORF1, ORF2, and ORF3. These ORFs encode different viral proteins, which are involved in viral replication, packaging and regulation of host immune response.
• ORF1 encodes a nonstructural polyprotein that performs multiple functions during viral replication, including RNA replicase activity.
• ORF2 encodes the major capsid protein of the virus, which is the main component of the virion and one of the major antigens recognized by the immune system.
• ORF3 encodes a small multifunctional protein that regulates viral release, inhibits apoptosis in host cells, and may affect immune escape.
Hepatitis E virus is divided into eight genotypes, mainly four genotypes. Types 1 and 2 only infect humans and cause waterborne epidemics mainly in developing countries, while types 3 and 4 can infect humans and a wide range of animals, showing zoonosis.

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Epidemiology of hepatitis E

Hepatitis E, as a disease prevalent mainly in developing countries in Asia and Africa, often presents a large-scale epidemic trend in these regions. In contrast, in developed countries, the disease usually appears as isolated sporadic cases. Over the past 50 years, nearly 10 major HEV outbreaks with more than 10,000 cases have been recorded worldwide. Among them, the most serious one occurred in Xinjiang, China, between 1986 and 1988. In this outbreak, a total of 119,280 people were infected, resulting in 707 tragic deaths, including 414 deaths of pregnant women, which highlights the serious threat of hepatitis E to certain populations. The scale and impact of this outbreak not only highlights the seriousness of hepatitis E, but also reflects the challenges of public health systems in dealing with outbreaks.

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Main route of transmission of hepatitis E?

The epidemic pattern of HEV is similar to that of hepatitis A. HEV is mainly transmitted by fecal-oral route, that is, infection through ingestion of water or food contaminated with the virus, and can also be transmitted through direct contact with infected animals or their excreta. Among them, the epidemic caused by water pollution is the most common, and a few cases are caused by food pollution or close contact in daily life. Outbreaks of hepatitis E also exhibit a marked seasonal pattern, occurring frequently after rainy seasons or floods. Most of the patients are young adults, it is worth noting that the susceptibility of pregnant women to the virus is significantly increased, once infected, the condition is often more serious, and the mortality rate is relatively high. In addition, hepatitis E does not show a clear tendency to spread in family clusters, which is different from the transmission patterns of some other infectious diseases.

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Clinical diagnostic methods

The clinical diagnosis of hepatitis E usually involves serological tests (for anti-HEV IgM and IgG antibodies) and molecular tests (such as RT-PCR, for viral RNA) that help confirm acute and previous infection. At present, although most patients with hepatitis E can recover spontaneously, the infection may be more serious for some high-risk groups, such as pregnant women and immunocompromised people, so prevention and timely diagnosis are very important.