L9: Liver Diseases: Viral Infections and their Complications

What are the main etiologies of hepatitis?

Hepatitis viruses, alcoholism, obesity (MASLD/NASH), drugs, autoimmune diseases, metabolic diseases (e.g., Wilson's disease).

How is Hepatitis A primarily transmitted?

Through the fecal-oral route, often from contaminated food like poorly cooked shellfish.

Describe the key features of Hepatitis A virus (HAV).

Fecal-oral transmission (undercooked shellfish, infected individuals). Incubation: 15–40 days. No chronicity; 99% recovery. Direct cytopathic effect.

What is the primary route of transmission for Hepatitis B?

Parenteral route through blood and body fluids, including sexual contact and vertical transmission.

What are common long-term complications associated with chronic Hepatitis B?

Cirrhosis and hepatocellular carcinoma (HCC).

What is the key characteristic of cirrhosis?

It is an end-stage liver disease characterized by diffuse process affecting the whole liver and regenerative nodules surrounded by fibrous connective tissue

What is the primary complication of cirrhosis related to liver function?

Portal hypertension leading to esophageal varices, ascites, and hepatic encephalopathy due to portosystemic shunting and splenomegaly.

How does hepatic encephalopathy develop in cirrhosis?

Liver failure impairs detoxification of nitrogenous waste (e.g., ammonia), causing neurotoxicity (confusion, coma, flapping tremor).

Why is ascites common in cirrhosis?

Portal hypertension increases hydrostatic pressure, and hypoalbuminemia reduces oncotic pressure, leading to fluid leakage into the peritoneal cavity.

What are the risk factors for developing hepatocellular carcinoma (HCC)?

Chronic HBV or HCV infection, chronic alcoholism, obesity or metabolic disorders (e.g., type 2 diabetes), exposure to aflatoxins.

What are the key features of HEV?

HEV is a major cause of acute hepatitis in HK. Transmitted via fecal-oral route; subclinical infections are common. No chronic infection.

How does metabolic-dysfunction associated steatotic disease (MASLD) relate to liver health?

It can lead to fatty liver disease and increase the risk of cirrhosis and hepatocellular carcinoma.

What are the signs of acute hepatitis?

Jaundice, malaise, anorexia, and the presence of apoptotic or acidophil bodies.

What is the one curative treatment for cirrhosis?

Liver transplant.

What is the characteristic appearance of hepatocellular carcinoma?

Hemorrhagic, necrotic, soft tumors (due to high vascularity, minimal stroma). Prone to rupture and intraperitoneal bleeding.

What are the two main serological markers for Hepatitis C virus?

Anti-HCV (not protective) and HCV RNA.

Describe the epidemiology of HCC in Hong Kong.

60–80% of HCC cases are linked to cirrhosis; >80% associated with HBV. Male:female ratio = 3.5:1. Insidious onset.

What is non-alcoholic steatohepatitis (NASH)?

A type of liver inflammation that occurs in those with fatty liver disease without significant alcohol consumption.

What is the role of cccDNA in HBV infection?

Covalently closed circular DNA (cccDNA) integrates into the host nucleus, enabling lifelong viral persistence. Its quantity guides treatment decisions.

Compare HBV and HCV in terms of chronicity and treatment.

Both cause chronic hepatitis. HBV has a vaccine but no cure; HCV lacks a vaccine but has curative antiviral drugs (e.g., direct-acting antivirals).

What are the three phases of chronic HBV infection?

1. Immune tolerance: High HBV DNA, normal ALT.

2. Immune clearance: Fluctuating HBV DNA/ALT, active hepatitis.

3. Residual phase: Low HBV DNA; cirrhosis/HCC risk.

Name two common histological features of acute and chronic hepatitis.

Apoptotic (acidophil) bodies and hepatocellular necrosis.

List the etiologies of cirrhosis.

Chronic viral hepatitis (HBV, HCV, HDV), alcoholism, MASLD/NASH, autoimmune hepatitis, primary biliary cirrhosis, Wilson’s disease, and cryptogenic causes.