Recently, there have been cases of acute hepatitis in young children in many countries in Europe and the United States, and some children need liver transplant treatment. At present, the total number of cases has increased suddenly, and the number of confirmed cases in the UK alone has reached 108, which has attracted the attention of the World Health Organization. Information from patient samples and surveillance systems shows that 77% of cases are adenovirus positive. Adenovirus, a common virus, usually causes only mild illness, and there have been no previous reports of severe hepatitis caused by adenovirus. Could it be that the virus has mutated? What measures can be taken to prevent adenovirus infection? Let's combine the relevant information now to explain the main points for you.
Let's first review the sudden increase in acute hepatitis cases. On 5 April 2022, the UK Health Department informed the World Health Organization of 10 cases of severe acute hepatitis in infants and young children, with patients aged between 11 months and 5 years, the earliest case developing symptoms in January 2022 and the remaining 9 cases detected in March. As of 8 April, a total of 74 similar cases have been detected in the UK. The main manifestations of these children were acute hepatitis, significantly elevated levels of liver enzymes, and symptoms of jaundice or gastrointestinal tract, and 6 of them received liver transplantation. On 21 April, the UK Health Department's latest report showed that 34 more cases had been detected, bringing the total number of cases to 108.
Following the reporting of cases of acute hepatitis in the UK, Ireland subsequently reported 5 cases, Spain reported 3 cases, France reported 2 cases, and Denmark and the Netherlands also reported cases. On 19 April, nine similar cases of children were reported in a state across the ocean in the southeastern United States, one of which was detected in October 2021. Currently, preliminary confirmation of the cause shows that in 77% of cases, the test result is positive for adenovirus. The specific source of infection points to adenovirus-41 type. Given the current emergency, WHO strongly recommends that countries identify, investigate, and report potential cases that meet the definition.
Adenovirus, or HAdV for short, was first isolated from surgically removed children's adenoids and tonsils in 1953, and the same virus was subsequently isolated in the secretions of patients with respiratory diseases. It was officially named in 1956 and divided into 7 species from A to G, and more than 90 genotypes have been found.
Adenovirus, a common virus that causes respiratory infections in children, is caused by 4% to 10% of pneumonia, especially in young children under 5 years of age, who are susceptible to infection. In the past, respiratory infections caused by adenovirus have been mainly sporadic cases, but there have been localized small-scale epidemics or large-scale atrocities. For example, there was a major adenovirus outbreak in the new barracks of the United States, which was controlled after the use of the vaccine, and then it reappeared after the vaccine was discontinued in 1999. In 2007, there were adenovirus outbreaks in 4 states in the United States, with a mortality rate of about 4%. Here, in the 1960s, there was a pandemic of infant adenovirus pneumonia, and the case fatality rate was high. Since then, there have been many local and small-scale epidemic events.
Adenovirus, a double-stranded DNA virus without an envelope, is a symmetrical structure of a 20-sided body with a diameter of about 70 to 90 nanometers, which multiply mainly within cells. Adenovirus infection, which mainly induces a non-specific natural immune response from the host, causes edema, hyperemia, necrosis of the mucosa of bronchi and bronchiol, necrosis, increased mucus secretion, airway obstruction, and in severe cases, will destroy elastic fibers, cartilage, smooth muscle, resulting in continuous lung function damage. In addition to the respiratory system, adenoviruses also affect the central nervous system, circulatory system, blood system, and at present, adenoviruses have been isolated in almost all human organs. Therefore, the possibility of adenovirus infection causing hepatitis is present. Previously, Stanford University has reported 12 cases of adenovirus hepatitis, but past cases have occurred mainly in immunocompromised people. This time, are the cases of acute hepatitis in Europe and the United States caused by adenovirus mutations? This question needs to wait for subsequent scientific research to verify.
Adenovirus, which can infect people of all ages, the most common route of infection is respiratory infection, and in groups with weak immune function, it can cause pneumonia and even organ failure. Adenovirus transmission occurs mainly in closed, crowded, and humid environments, and wearing masks and washing hands frequently can prevent infection. The main mode of transmission of adenovirus is droplet transmission, which can also be transmitted through the feces of infected people, and the incubation period of the virus is an average of 3 to 8 days, and infected people and patients usually need to be isolated and managed. At present, for adenovirus infection, the lack of specific drugs and the effect of broad-spectrum antiviral drugs are still in the stage of clinical research evaluation. Therefore, the main measure to deal with adenovirus infection is now symptomatic treatment.
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