Hepatitis B Explained

Introduction

• Hepatitis B is a major global health issue.
• Statistics (2015): 257 million people with chronic Hepatitis B; nearly 900,000 deaths.

Background on Hepatitis B

• Definition: Life-threatening liver infection caused by the Hepatitis B Virus (HBV).
• Risks: High risk of death from cirrhosis (liver scarring) and liver cancer.
• Prevalence: 6% in the western Pacific and African regions. Rare in North America due to vaccination.

Transmission

• Primary Modes:
  • From mother to child at birth.
  • Sexual transmission.
  • Sharing contaminated needles.
• Infected Bodily Fluids: Blood, saliva, menstrual fluid, vaginal fluid, seminal fluid.

Symptoms of Hepatitis B

• Many are asymptomatic initially.
• Possible acute illnesses:
  • Yellowing of skin and eyes (jaundice).
  • Dark urine.
  • Extreme fatigue.
  • Nausea and vomiting.
  • Abdominal pain.
• Some may develop acute liver failure, potentially fatal.
• Chronic Hepatitis B can worsen into cirrhosis or liver cancer.

Mechanism of Hepatitis B Infection

• Virus Structure: HBV has a casing (capsid) and DNA.
• Infection Process:
  • Binds to liver cell (hepatocyte) receptors.
  • Invades and utilizes host cell to replicate.
• Immune Response:
  • Body's immune system attacks infected hepatocytes.
  • Involves cytotoxic T-cells (CTLs) that kill infected cells.
  • CD8 T-cells play a key role in fighting HBV.

T-Cell Activation and Response

• Activation: Requires recognition of antigens via MHC complex and co-stimulatory signals.
• Role of CD8 T cells: Important for controlling HBV infection; effective in acute phase but often dysfunctional in chronic cases.
• Dysfunction Mechanisms: In chronic infections, reduced co-stimulatory molecules, impaired proliferation, and cytokine secretion leads to T-cell exhaustion.
  • Exhausted T-cells exhibit:
    • Dysfunctional proliferation.
    • Impaired cytokine production.
    • Increased apoptosis.

Prevention and Treatment

• Vaccination:
  • Effective vaccine offers 98-100% protection.
  • WHO recommends vaccination for infants within 24 hours of birth.
• Treatment:
  • No specific cure for acute Hepatitis B; care focuses on comfort and nutrition.
  • Chronic infection may be treated with oral antiviral agents to slow progression and improve outcomes.

Conclusion

• Hepatitis B is a critical health risk, potentially leading to life-threatening conditions.
• Importance of Vaccination: Ensures protection against infection.
• Healthcare Consultation: Important for diagnosis and management.