Overview
Hepatitis B is an infectious disease of the liver caused by the hepatitis B virus. In adults and older children, it is usually self-limiting with transient infection. In infants and younger children, it is generally asymptomatic but often results in chronic infection.
Adults & Older Children
- Usually self-limiting
- Transient infection
- 90% achieve lifelong immunity
- Inflammation resolves
Infants & Young Children
- Generally asymptomatic
- High rate of chronic infection
- Perinatal transmission common
- Long-term complications risk
Transmission
UK Epidemiology
- 95% of chronic infections in migrant populations
- Acquired perinatally in country of birth
- Adult infections: sexual contact or drug use
Blood-to-Blood Contact
- Sharing drug injecting equipment
- Occupational needlestick injuries
- Blood transfusions and products
- Tattoos, piercing, acupuncture
- Household contact (razors, toothbrushes)
Sexual Transmission
- Via mucous membranes
- Vaginal, anal, and oral sex
- High risk in MSM
- Multiple partners increases risk
Vertical Transmission
- Perinatal transmission common
- During childbirth
- Uncommon in utero
- NOT transmitted via breastfeeding
Risk Factors
Behavioral Risks
- Injecting drug users & contacts
- Frequent sexual partner changes
- Men who have sex with men
- Sex workers and clients
- Unprotected sexual activity
Geographic & Occupational
- Travel to high prevalence areas
- From high prevalence countries
- Healthcare workers
- Laboratory staff
- Prison inmates and staff
Medical & Social
- Household contacts of HBV+
- Regular blood product recipients
- Chronic renal/liver disease
- Infants of HBV+ mothers
- Looked-after children
Clinical Features
Acute Infection
- Prodromal illness: fever, arthralgia, rash
- Malaise, fatigue, fever
- Nausea, poor appetite
- Right upper quadrant pain
- Jaundice with dark urine/pale stools
- Extrahepatic manifestations
Chronic Infection
- Often no physical signs initially
- Spider naevi
- Finger clubbing
- Jaundice
- Hepatosplenomegaly
- Signs of advanced liver disease
Disease Progression Timeline
Visual timeline from exposure to chronic complications
Investigations & Serology
Hepatitis B Serology Markers
Key Markers Explained
- HBsAg: Viral envelope - indicates infectiousness
- HBeAg: High replication & infectivity marker
- Anti-HBe: Clearance of HBeAg - decreased infectivity
- Anti-HBc: Current or past infection
- Anti-HBs: Recovery and immunity
- HBV DNA: Viral load - progression risk
Serological Patterns in Different Disease States
| Disease State | HBsAg | HBeAg | Anti-HBe | Anti-HBc | Anti-HBs | HBV DNA |
|---|---|---|---|---|---|---|
| Acute Hepatitis B | + | + | - | + | - | + |
| Chronic Hepatitis B (Active) | + | +/- | +/- | + | - | + |
| Chronic (Inactive Carrier) | + | - | + | + | - | + (low) |
| Immunity (Past Infection) | - | - | +/- | + | + | - |
| Immunity (Vaccination) | - | - | - | - | + | - |
Additional Investigations
Liver Function Tests
- ALT/AST: 500-10,000 IU/L
- Bilirubin: 85.5-500 micromols/L
- Alkaline phosphatase: <2x ULN
- Higher if cholestasis present
Other Essential Tests
- Full blood count
- Prothrombin time
- Hepatitis A, C, D, HIV serology
- Alpha fetoprotein
- Liver ultrasound
Management
Referral Protocol
Refer ALL HBsAg positive patients to hepatologist/gastroenterologist/infectious disease specialist with hepatology interest for treatment consideration and monitoring.
Acute Hepatitis B
- Supportive care only
- Symptomatic management
- Rest and hydration
- Monitor for complications
- Usually self-resolving
Chronic Hepatitis B
- Prevent progression to cirrhosis
- Reduce hepatocellular cancer risk
- Antiviral therapy
- Regular monitoring
- Rarely curative
Treatment Options
| Treatment | Type | Indications | Notes |
|---|---|---|---|
| Peginterferon alfa-2a | Immunomodulator | Selected chronic cases | Limited duration therapy |
| Tenofovir/Entecavir | Antiviral | Chronic active hepatitis | Long-term suppression |
| Liver Transplant | Surgical | End-stage liver disease | Last resort option |
Patient Advice
- Avoid alcohol completely
- Minimize transmission risk to contacts
- Notify Health Protection Unit
- Regular follow-up essential
- Vaccinate household contacts
Post-exposure Prophylaxis
High Risk Exposure Groups
- Babies of HBV+ mothers
- Needlestick injuries
- Sexual assault victims
- Injecting drug users
- MSM and sex workers
- Close family contacts
Vaccination Schedules
Rapid Schedule
- 0, 1, 2 months
- OR over 21 days
- Needlestick injuries
- Imminent travel
- Quick protection needed
Standard Schedule
- 0, 1, 6 months
- Good compliance expected
- Rapid protection not needed
- Longer-term planning
Immunoglobulin Prophylaxis
- Give WITH first vaccine dose
- For non-immune exposed individuals
- Ideal within 48 hours of exposure
- Discuss with microbiologist/HPU first
- Intramuscular administration
Complications
Fulminant Hepatitis
- Rare (<1% of acute cases)
- Rapid liver failure
- Coagulopathy
- Encephalopathy
- Cerebral oedema
- Life-threatening
Chronic Infection
- HBsAg+ >6 months
- Immune system failure to clear virus
- Host immune response causes damage
- Leads to chronic inflammation
Long-term Sequelae
- Chronic hepatitis
- Cirrhosis
- Hepatocellular carcinoma
- Liver failure
Extrahepatic Manifestations
- Glomerulonephritis
- Vasculitis
- Polyarteritis nodosa
- Can occur in acute and chronic infection
- Immune complex mediated
Complications Progression Pathway
From initial infection to long-term complications