May 2022 acute hepatitis outbreak, is there a role for COVID-19 and other viruses?

Figure 1 Reported cases of acute hepatitis syndrome of unknown aetiology in children. A: April 2022; B: May 2022. Apr: April; The UK: The United Kingdom; The USA: The United States of America.

Figure 2 Flow chart of studies included in this review.

Figure 3 Gut-liver axis. Mutual effects of the gut and liver through systemic and portal circulation and biliary enterohepatic circulation. HFD: High-fat diet; IgA: Immunoglobulin A; SCFAs: Short-chain fatty acids; TMAO: Trimethylamine N-oxide; VLDL: Very-low-density lipoprotein.

Figure 4 Effect of coronavirus disease 2019 infection on the liver as indicated by increased liver enzymes. The virus reaches the liver from the gut-liver-lung axis and may be re-shed back to the gut through the bile. These effects are mediated through the impact of hypoxia, systemic venous congestion, immune-mediated hepatic damage by inflammatory mediators induced by severe acute respiratory syndrome coronavirus-2 infection (SARS-CoV-2), the direct hepatic cytopathic effect of SARS-CoV-2, and the hepatotoxic effects of some medications used to treat SARS-CoV-2 infection such as azithromycin, chloroquine, lopinavir, ritonavir, and tocilizumab. GIT: Gastrointestinal tract; IL-6: Interleukin 6.

Figure 5 Summary of the treatment of acute hepatitis of unknown cause. AHUC: Acute hepatitis of unknown cause; GI: Gastrointestinal; HE: Hepatic encephalopathy; ICT: Increased intracranial tension.