Viral Hepatitis I: Introduction

Viral hepatitis is an inflammatory condition of the liver caused by infection with hepatotropic viruses, most commonly hepatitis A, B, C, D, and E. Despite variations in structure and transmission, all viruses mentioned infect hepatocytes and provoke immune responses that can hinder liver function. Additionally, some non-hepatotropic viruses can also lead to hepatic inflammation.

Hepatitis A Virus

Hepatitis A virus (HAV) is transmitted through the fecal–oral route, typically by ingestion of food or water contaminated with fecal material from an infected person. After entering the gastrointestinal tract, the virus reaches the liver and infects hepatocytes, resulting in an acute, self-limiting illness.

Hepatitis B Virus

Hepatitis B virus (HBV) is a DNA virus spread through infected blood and body fluids. Transmission occurs through sexual contact, sharing of needles, occupational exposures such as needlestick injuries, and vertical transmission from mother to infant during childbirth. HBV infection may be acute or progress to chronic disease.

Hepatitis C Virus

Hepatitis C virus (HCV) is an RNA virus transmitted primarily via blood exposure. Common routes include sharing drug-injection equipment, unsafe tattooing or piercing practices, and, less commonly, sexual contact involving blood exposure.

Hepatitis D Virus

Hepatitis D virus (HDV) is a defective RNA virus that requires HBV for replication. HDV infection may occur as a coinfection—when HBV and HDV enter hepatocytes simultaneously—or as a superinfection in individuals already chronically infected with HBV. HDV typically worsens the severity of hepatitis.

Hepatitis E Virus

Hepatitis E virus (HEV) is an RNA virus transmitted through the fecal–oral route, most often via contaminated water. HEV generally causes acute hepatitis, but Infection can be especially severe in pregnant individuals, particularly during the third trimester.

Other Viral Causes

Additional viruses, such as Epstein–Barr virus, cytomegalovirus, and yellow fever virus, may also cause hepatitis as part of a systemic infection.