Zhang Wenhong: Unexplained hepatitis in children is not uncommon This year shows a cluster of diseases

The recent detection of cases of unexplained hepatitis in children in many countries is of great concern, and WHO also said that it is closely monitoring the development of cases in various countries.

On 29 April, Professor Zhang Wenhong, Director of the National Center for Infectious Diseases Medicine and Director of the Department of Infectious Diseases at Huashan Hospital affiliated to Fudan University, expressed his views on the "Huashan Infection" public account on the unexplained hepatitis in children concerned by WHO.

Zhang Wenhong wrote in an article entitled "Outbreaks and Causes of Hepatitis in Children of Unknown Causes in The United Kingdom and Other Places": "Cases of hepatitis of unknown cause occur every year, often referring to liver damage caused by no known hepatitis virus or known causes, which is not uncommon in children. However, hepatitis of unknown cause of concern to WHO this time has the characteristics of cluster incidence, and the incidence rate is higher than in previous years. ”

Zhang Wenhong said that in this case, it is reasonable to consider the risk of infectious diseases.

Be wary of the risk of emerging infectious diseases

Of the 169 cases currently published by WHO, 74 children have tested positive for adenovirus, of which 18 have been identified as adenovirus type 41. Uk health agencies say unexplained hepatitis in children may be associated with adenovirus infection.

In this regard, Zhang Wenhong said that adenovirus infection is a very common phenomenon, but he told the first financial reporter: "Adenovirus generally invades the lungs and causes pneumonia or diarrhea. ”

Zhang Wenhong said it is still impossible to explain why there have been so many cases of severe hepatitis this year, and only in children. "One hypothesis is that children have not been exposed to the virus for a long time, and sudden exposure can cause more serious immune damage." "This speculation is consistent with the phenomenon that emerging infectious diseases tend to be heavier early in the outbreak," he writes. If this is the cause, rather than a new virus that has not been detected before, the subsequent effects of this unexplained hepatitis will gradually decline. ”

Zhang Wenhong stressed that even if the probability of a new infectious disease pandemic is not high, it should still be vigilant against unknown pathogens.

Xie Youhua, vice president of the Shanghai Institute of Major Infectious Diseases and Biosafety, analyzed in the article "Outbreaks and Causes of Hepatitis in Children of Unknown Causes in the United Kingdom and Other Places" that although it is currently speculated that adenovirus infection may be one of the potential factors leading to severe acute hepatitis in children, it is still impossible to explain the severity of its clinical symptoms.

Acute hepatitis caused by adenovirus infection is uncommon, especially in immunocompetent children, although there have been case reports of hepatitis developing after infection with adenovirus in immunocompromised children. It is unclear whether adenovirus type 41 infection is the cause of acute hepatitis in healthy children.

"One of the current speculations about the occurrence of unexplained hepatitis in children is a new variant of a known virus, possibly adenovirus, but the possibility of other pathogens, such as variants of coronavirus, rhinovirus, enterovirus, parainfluenza virus, etc., cannot be ruled out." Xie Youhua and others wrote.

Although there is currently no evidence link between COVID-19 and unexplained hepatitis in children, Xie Youhua et al. pointed out in the article that it is also possible that children have an unusual immune response or disease manifestations based on the previous COVID-19 infection, followed by subsequent infection with adenovirus or other viruses, or co-infection with adenovirus or other viruses.

The presence or absence of cases in the country has yet to be investigated

Zhang Wenhong also said that with the deepening of understanding, the definition of confirmed cases is also constantly updated.

In this regard, Wang Xinyu, deputy chief physician of the Department of Infectious Diseases of Huashan Hospital, explained in the comment area of the "Huashan Infection" article that WHO has updated the case definition on April 23, which has changed greatly from the previous week, mainly divided into two points, the first is to cancel the original definition of confirmed cases, that is to say, in the absence of a clear cause, the definition of confirmed cases is no longer set; in addition, cases aged 16 years and below, transaminases greater than 500 IU/L are combined into suspected cases This was followed by an increase in the case's retrospective time by 3 months, pushing forward to 1 October 2021.

WHO predicts that the number of cases of hepatitis in children of unknown origin is likely to continue to increase in the future, and the Agency strongly encourages Member States to identify, investigate and report potential cases that meet the definition of cases. Member States should collect information on epidemiological and risk factors and submit it to WHO and partner agencies through agreed reporting mechanisms.

WHO also said that any epidemiological link between cases may provide clues to trace the source of the disease, and the timing and geographic information about the case and the potential risk factors for its close contacts should be reviewed. WHO also recommends that whole blood, serum, urine, stool and respiratory samples, as well as liver biopsy samples,if any, should be tested to further understand the virus's characteristics using methods including sequencing. Other infectious and non-communicable causes also require thorough investigation. Non-infectious factors refer to environmental toxins, drugs, etc.

The first financial reporter learned from the Chinese Center for Disease Control and Prevention that there are currently no cases of unexplained hepatitis in children in China.

Xie Youhua and others wrote in the article that the existence of similar unexplained childhood hepatitis on the mainland still needs to be investigated. According to the criteria for confirmed cases, the incidence of hepatitis of unknown cause in children in the mainland can be collected since January 1, 2022, compared with the data of previous years, and whether there is also an increase in hepatitis cases of unexplained children in the mainland. On the other hand, because of the imported risk of the disease, preparation must be made early.

Xie Youhua cited data to say that the detection rate of adenovirus in children's diarrhea samples in mainland China is high, such as the detection of pathogens in children (<5 years old) in Sanjiang Dong Autonomous County, Liuzhou City, Guangxi Zhuang Autonomous Region, showing that the detection rate of adenovirus 40 and 41 types is 16.5%, and the detection rate of other adenoviruses is as high as 39.1%.