Hepatitis B

Hepatitis B is a viral infection caused by the Hepatitis B virus (HBV), which primarily affects the liver and can lead to acute or chronic liver disease, cirrhosis, and hepatocellular carcinoma.

Definition

Hepatitis B is a viral infection caused by the Hepatitis B virus (HBV), which primarily affects the liver and can lead to acute or chronic liver disease, cirrhosis, and hepatocellular carcinoma.

Epidemiology

Global prevalence: ~296 million chronic carriers worldwide
Higher prevalence in sub-Saharan Africa, East Asia, and parts of the Pacific Islands
Transmission occurs perinatally, via blood, sexual contact, or contaminated needles
Chronic infection more likely when infected in infancy or early childhood
Males and females are affected equally, but males have higher risk of complications

Etiology

Hepatitis B virus (HBV), a partially double-stranded DNA virus of the Hepadnaviridae family
Transmission: perinatal (mother to child), sexual, parenteral (needles, transfusions), hemodialysis, occupational exposure
Risk factors: unvaccinated individuals, IV drug use, multiple sexual partners, healthcare workers, endemic regions

Pathophysiology

HBV infects hepatocytes via NTCP receptor binding
Viral replication within hepatocytes triggers immune-mediated cytotoxicity
Acute infection may be cleared by immune system or progress to chronic infection
Chronic inflammation leads to fibrosis, cirrhosis, and increased risk of hepatocellular carcinoma
Viral antigens (HBsAg, HBeAg) correlate with infectivity and replication