5.18
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. De…
Viral hepatitis is liver inflammation caused by a viral infection that targets hepatic tissue. The most common causes are viruses of the hepatitis family, A-E.
The hepatitis A virus spreads through contaminated food or water via the fecal-oral route.
Hepatitis B is a DNA virus transmitted through infected blood and body fluids. Common routes include sexual contact, occupational exposure, particularly needlestick injuries, and perinatal transmission from mother to child.
Hepatitis C is an RNA virus transmitted primarily through exposure to blood. Common routes include sharing drug needles and unsafe tattooing practices.
The hepatitis D virus is a defective RNA virus that requires HBV to infect. It can occur as a coinfection, that is, when HBV and HDV enter hepatocytes together, or as a superinfection, when HDV infects someone already carrying HBV.
The hepatitis E virus is an RNA virus spread via the faecal-oral route, commonly through contaminated water.
Additionally, other viruses, such as Epstein–Barr virus, cytomegalovirus, and yellow fever virus, can also cause hepatitis.
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Q1: How does hepatitis A virus spread from person to person?
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.
Q2: What are the main transmission routes for hepatitis B virus?
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.
Q3: Why is hepatitis D virus dependent on hepatitis B virus?
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.
Q4: How does hepatitis C virus primarily transmit between individuals?
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.
Q5: What distinguishes hepatitis E virus transmission and clinical course?
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.
Q6: Can viruses other than hepatitis A-E cause liver inflammation?
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.
Q7: What is the fundamental mechanism by which viral hepatitis damages the liver?
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.