Unexplained hepatitis refers to cases where patients exhibit acute hepatitis symptoms that are not caused by hepatitis A, B, C, D, or E viruses, also known as non-hepatotropic viral hepatitis. On March 31, 2022, the UK first reported five cases of severe acute hepatitis of unknown origin in children. Subsequently, suspected cases were reported in multiple countries worldwide. As of November 2022, 1,010 cases have been reported in 35 countries, primarily affecting children under five years old, with approximately 5% of cases requiring liver transplantation, indicating a high severity rate. Possible causes of unexplained hepatitis include infections by viruses other than hepatitis viruses and autoimmune reactions. Newly emerging acute hepatitis refers to outbreaks of hepatitis caused by newly discovered pathogens or other factors. Research has indicated that the etiology and pathogenesis of unexplained hepatitis in children are related to infections by human adenovirus, adeno-associated virus 2 (AAV2), and cytomegalovirus. European countries conducted adenovirus testing on 457 children, with a positivity rate of 51.6% (236 cases). Two studies in the UK found high levels of AAV2 in the blood and liver samples of some children through metagenomic sequencing and PCR testing, although the specific pathogenesis remains unclear. Unexplained hepatitis and newly emerging acute hepatitis can cause a significant disease burden. Reports and discoveries in China are relatively rare. To accurately understand the incidence and pathogenic mechanisms of unexplained and newly emerging acute hepatitis in China, it is crucial to conduct monitoring, pathogen screening, and diagnostic system research. This project aims to collect blood and liver tissue samples of unexplained and newly emerging acute hepatitis through a monitoring system. After excluding infections of hepatitis A-E viruses using enzyme immunoassay, chemical, and photometric methods to detect infection markers, multiplex PCR technology and other methods will be employed to establish a pathogen detection platform for unexplained hepatitis. This will involve nucleic acid testing for common non-hepatotropic viruses that cause liver damage and constructing a stable multiplex PCR reaction system to achieve rapid screening and diagnosis of clinical samples. Understanding the incidence and dynamic trends of unexplained and newly emerging acute hepatitis, and studying their etiology and influencing factors through pathogen screening and diagnostic research, will provide technical support for the prevention and control of these conditions.
