🇬🇧 Around 180,000 people in the UK are infected with HBV, many asymptomatic and unaware.
🌍 Globally, HBV causes 1–2 million deaths per year (cirrhosis, hepatocellular carcinoma).
Highly infectious double-stranded DNA virus.
Endemic in the Middle East, Asia, and Africa.

Transmission

🩸 Blood products & needle sharing
💉 Vertical transmission (mother → baby, esp. if HBeAg +ve)
❤️ Sexual transmission

Virology

Antigens: HBsAg (surface), HBcAg (core), HBeAg (envelope)
Antibodies: anti-HBs, anti-HBc (IgM & IgG), anti-HBe

Serology – Key Markers

Marker	Meaning
HBsAg	Earliest marker, present in acute or chronic infection. Persistence >6 months = carrier.
HBcAg	Not detected in serum; antibodies to core (IgM/IgG) are useful markers.
HBeAg	Indicates active replication & high infectivity. Persistence = chronic active infection.
Anti-HBs	Recovery & immunity (post-infection or vaccination).
Anti-HBc IgM	Recent infection (within 6 months).
Anti-HBc IgG	Past infection, persists lifelong.

Typical Serological States

State	HBsAg	anti-HBc	anti-HBs	IgM anti-HBc
Susceptible	-	-	-	-
Immune (natural)	-	+	+	-
Immune (vaccinated)	-	-	+	-
Acute infection	+	+	-	+
Chronic infection	+	+	-	-

Clinical Course

⏱️ Incubation 2–6 months; many subclinical.
Acute hepatitis: fever, malaise, rash, arthritis, jaundice, ↑ALT/AST, HBsAg+, IgM anti-HBc.
Chronic infection: develops in ~10% adults; higher in neonates/children (esp. vertical transmission).
Complications: cirrhosis, hepatocellular carcinoma (HCC).

Risks for Chronicity

Vertical transmission in infancy (high risk, 90% → chronic)
Immunosuppression, male sex, family/genetic factors

🔎 Investigations

Bloods: LFTs, HBV DNA, serology panel.
Biopsy or elastography for fibrosis staging.
Screen for HIV, HCV, HDV co-infections.

💊 Management

Supportive: most acute infections resolve.
Chronic infection: treat if:
- HBV DNA ≥20,000 IU/ml
- ALT persistently raised
- Evidence of fibrosis/cirrhosis
Antivirals:
- Pegylated interferon-alpha (weekly injections) – less used now.
- Tenofovir or Entecavir – preferred, potent nucleos(t)ide analogues.
- Lamivudine, Adefovir – older, limited by resistance.
Liver transplant: option for end-stage disease.

Prevention

💉 Universal immunisation – especially healthcare workers, dialysis patients, babies of HBsAg +ve mothers.
Post-exposure prophylaxis: HBIG + vaccination after needlestick or birth to HBsAg +ve mother.
Safe sex, no needle sharing.

References

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Hepatitis B

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