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World J Gastroenterol. Jul 28, 2021; 27(28): 4603-4638
Published online Jul 28, 2021. doi: 10.3748/wjg.v27.i28.4603
Viral hepatitis: Milestones, unresolved issues, and future goals
Pietro Torre, Andrea Aglitti, Mario Masarone, Marcello Persico
Pietro Torre, Andrea Aglitti, Mario Masarone, Marcello Persico, Internal Medicine and Hepatology Unit, Department of Medicine, Surgery and Dentistry, “Scuola Medica Salernitana,” University of Salerno, Salerno 84081, Italy
Author contributions: Torre P and Aglitti A gave the same contribution in designing and writing the paper; Masarone M and Persico M supervised the work.
Conflict-of-interest statement: Authors declare no conflict of interests for this article.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Marcello Persico, MD, Full Professor, Internal Medicine and Hepatology Unit, Department of Medicine, Surgery and Dentistry, “Scuola Medica Salernitana,” University of Salerno, Via Salvador Allende, Salerno 84081, Italy.
Received: February 27, 2021
Peer-review started: February 27, 2021
First decision: March 27, 2021
Revised: April 11, 2021
Accepted: June 16, 2021
Article in press: June 16, 2021
Published online: July 28, 2021

In this review the current overall knowledge on hepatitis A, B, C, D, and E will be discussed. These diseases are all characterized by liver inflammation but have significant differences in distribution, transmission routes, and outcomes. Hepatitis B virus and hepatitis C virus are transmitted by exposure to infected blood, and in addition to acute infection, they can cause chronic hepatitis, which in turn can evolve into cirrhosis. It is estimated that more than 300 million people suffer from chronic hepatitis B or C worldwide. Hepatitis D virus, which is also transmitted by blood, only affects hepatitis B virus infected people, and this dual infection results in worse liver-related outcomes. Hepatitis A and E spread via the fecal–oral route, which corresponds mainly to the ingestion of food or water contaminated with infected stools. However, in developed countries hepatitis E is predominantly a zoonosis. Although hepatitis A virus and hepatitis E virus are usually responsible for a self-limiting hepatitis, a serious, rarely fatal illness is also possible, and in immunosuppressed patients, such as organ transplant recipients, hepatitis E virus infection can become chronic. The description of goals achieved, unresolved issues, and the latest research on this topic may make it possible to speculate on future scenarios in the world of viral hepatitis.

Keywords: Viral hepatitis, Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D, Hepatitis E

Core Tip: Viral hepatitis still endangers the health of millions of people around the world. In this review the path that led to the current knowledge in the field of viral hepatitis will be reported.