ウイルス性肝炎 I: 概要

Hepatitis A virus spreads through the fecal-oral route, typically when a person ingests food or water contaminated with fecal material from an infected individual. After entering the gastrointestinal tract, the virus reaches the liver and infects hepatocytes, causing an acute, self-limiting illness that resolves without chronic infection.

Hepatitis B virus spreads through infected blood and body fluids via sexual contact, sharing 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, making transmission prevention critical in healthcare settings.

Hepatitis D virus is a defective RNA virus that requires hepatitis B virus for replication and cannot infect hepatocytes independently. HDV infection occurs as coinfection when HBV and HDV enter hepatocytes simultaneously, or as superinfection in individuals already chronically infected with HBV, typically worsening disease severity.

Hepatitis C virus is an RNA virus transmitted primarily through blood exposure, including sharing drug-injection equipment and unsafe tattooing or piercing practices. Sexual contact involving blood exposure is a less common transmission route. HCV infection can lead to chronic hepatitis and requires careful prevention strategies.

Hepatitis E virus is an RNA virus spread via the fecal-oral route, most commonly through contaminated water. While HEV generally causes acute hepatitis, infection can be especially severe in pregnant individuals, particularly during the third trimester, distinguishing it from other hepatitis viruses in terms of pregnancy-related complications.

Yes, additional viruses such as Epstein-Barr virus, cytomegalovirus, and yellow fever virus can cause hepatitis as part of systemic infections. These non-hepatotropic viruses infect hepatocytes and provoke immune responses that can hinder liver function, though they are less common causes of viral hepatitis than the hepatitis family viruses.

Viral hepatitis causes liver inflammation when hepatotropic viruses infect hepatocytes and provoke immune responses that can hinder liver function. Despite variations in viral structure and transmission routes, all hepatitis viruses target hepatic tissue, resulting in inflammation that ranges from acute, self-limiting illness to chronic disease with potential complications.