What is hepatitis?

Definition of Hepatitis

Hepatitis is an acute inflammatory reaction in the liver that can be caused by viral infection, with the potential to progress to chronic disease, cirrhosis, hepatocellular carcinoma, and liver failure depending on the causative agent and host factors.

Core Pathophysiology

Hepatitis represents liver inflammation characterized by:

• Hepatic necroinflammation with elevated serum aminotransferase levels 1
• Acute onset with discrete symptoms and potential jaundice 2
• Progressive liver damage that may result in cirrhosis and hepatocellular carcinoma in chronic cases 3, 4

Clinical Manifestations by Type

Acute Hepatitis

• Defined by discrete onset of symptoms, presence of jaundice or elevated alanine transaminase levels 2
• Usually resolves spontaneously without chronic sequelae in most viral forms 5
• Up to 20% of patients may experience prolonged or relapsed course 5
• Less than 1% progress to acute liver failure 5

Chronic Hepatitis

• Persistence of viral markers for more than 6 months (e.g., hepatitis B surface antigen in HBV) 2
• Characterized by continued necroinflammation with elevated HBV DNA levels >2,000 IU/mL 1
• Places individuals at risk for hepatocellular carcinoma and cirrhosis 2
• Can result in decompensated liver disease with 300,000 HCV-related deaths occurring annually 4

Viral Etiologies

Hepatitis A (HAV)

• Causes acute self-limiting infection without chronic sequelae 5
• Over 150 million new infections occur annually 5
• Transmitted through fecal contamination of water and food 5

Hepatitis B (HBV)

• Partly double-stranded DNA virus causing both acute and chronic infection 2
• Chronic infection defined by persistence of surface antigen beyond 6 months 2
• Patients with HBeAg-negative chronic hepatitis tend to have lower HBV DNA levels (2,000-20 million IU/mL) and represent a later disease stage 1

Hepatitis C (HCV)

• Hepatotropic RNA virus with 57 million people living with infection globally in 2020 4
• Progressive liver damage resulting in cirrhosis and hepatocellular carcinoma 3
• Can cause both acute and chronic hepatitis 4

Hepatitis E (HEV)

• Fifth known form of viral hepatitis, one of the most frequent causes of acute viral hepatitis globally 6
• Majority of infections are asymptomatic with spontaneous viral clearance 6
• Can cause chronic hepatitis in immunocompromised patients 6

Key Clinical Pitfalls

Co-infections significantly alter disease severity and outcomes:

• Dual HBV and HCV infection increases cirrhosis and hepatocellular carcinoma rates compared to single infection 1
• HBV/HIV coinfection results in higher HBV DNA levels, lower spontaneous HBeAg seroconversion rates, and more severe liver disease 1
• HDV superinfection in HBV carriers almost always results in chronic infection with higher rates of cirrhosis and hepatic decompensation 1

Host factors affecting severity include:

• Immunological status, age, pregnancy, and underlying hepatic diseases 5
• Pregnant women and immunocompromised individuals face higher risk of adverse consequences 6