Related Subjects:
|Hepatitis A
|Chronic liver disease
|Liver Function Tests
|Ascites Assessment and Management
|Budd-Chiari syndrome
|Alcoholism and Alcoholic Liver Disease
|Liver Transplantation
🦠 Hepatitis A is an acute viral hepatitis caused by hepatitis A virus, usually transmitted by the faeco-oral route.
It does not cause chronic infection, unlike hepatitis B or C.
Most cases are self-limiting, but acute liver failure can rarely occur, especially in older adults and people with underlying chronic liver disease.
ℹ️ About
- 🦠 Hepatitis A virus is a picornavirus: a small, non-enveloped, single-stranded RNA virus.
- 💩 Transmission is mainly faeco-oral via contaminated food, water, close personal contact or sexual exposure.
- ⏱ Incubation is usually about 2–6 weeks, with an average of around 28–30 days.
- ✅ Infection usually gives lifelong immunity.
- 🚫 Hepatitis A does not cause chronic hepatitis or chronic carrier state.
- ⚠️ Acute liver failure is rare but more likely in older adults and those with pre-existing liver disease.
🌍 Epidemiology & Risk Factors
- 🍤 Contaminated food and water are classic routes, especially undercooked shellfish or food handled by an infectious person.
- 🌍 Risk is higher in areas with poor sanitation and limited access to clean water.
- ✈️ Travellers to endemic areas are at increased risk.
- ❤️ Sexual transmission can occur, particularly with oral-anal contact and during outbreaks among gay, bisexual and other men who have sex with men.
- 🏠 Household and close contacts of a case are at risk.
- 🩸 Blood-borne transmission is rare but possible during transient viraemia.
- 🛡 Severe disease risk is higher in older adults, immunosuppressed patients and people with chronic liver disease.
🧬 Pathophysiology
- HAV enters via the gastrointestinal tract and reaches the liver through the bloodstream.
- It replicates in hepatocytes and is excreted in bile, then shed in stool.
- Patients are most infectious in the period before jaundice appears.
- Liver injury is mainly immune-mediated, driven by cytotoxic T-cell responses against infected hepatocytes.
- This immune injury explains the marked ALT/AST rise seen in acute hepatitis.
🩺 Clinical Features
- 🤒 Prodrome: fever, malaise, fatigue, anorexia, nausea and abdominal discomfort.
- 🟡 Icteric phase: jaundice, dark urine, pale stools and pruritus.
- 🫀 Examination may show tender hepatomegaly; splenomegaly can occur.
- 👶 Children are often asymptomatic or mildly symptomatic.
- 👩⚕️ Adults are more likely to develop jaundice and prolonged symptoms.
- 🚬 Aversion to cigarettes is a classic exam clue but is not specific.
- 🔁 Some patients have prolonged or relapsing hepatitis, but chronic infection does not occur.
🚩 Red Flags - Consider Admission / Urgent Specialist Advice
- 🧠 Confusion, drowsiness or encephalopathy.
- 🩸 Raised INR or bleeding tendency.
- 🟡 Deepening jaundice or rapidly worsening liver blood tests.
- 🤮 Persistent vomiting or inability to maintain oral hydration.
- 💧 Significant dehydration.
- 🧓 Older patient, frailty, pregnancy, immunosuppression or chronic liver disease.
- 🩺 Severe abdominal pain, sepsis, hypotension or diagnostic uncertainty.
🔎 Investigations
- IgM anti-HAV: confirms acute or recent hepatitis A infection.
- IgG anti-HAV: indicates previous infection or vaccination and usually lifelong immunity.
- LFTs: ALT and AST often markedly raised; bilirubin may be raised; ALP is usually normal or mildly raised.
- Coagulation: check PT/INR if jaundiced, systemically unwell, vomiting, elderly, pregnant, immunosuppressed or underlying liver disease.
- U&E: assess dehydration and renal function if vomiting or poor oral intake.
- Other viral tests: consider HBV, HCV, HEV, EBV/CMV and HIV depending on risk factors and presentation.
- Imaging: ultrasound is not routine but may be useful if biliary obstruction, gallstones or alternative diagnosis is suspected.
🧪 Serology Interpretation
| Result |
Interpretation |
| Anti-HAV IgM positive |
Acute or recent hepatitis A infection. |
| Anti-HAV IgG positive, IgM negative |
Past infection or vaccination; immune. |
| Anti-HAV IgM negative, IgG negative |
Susceptible if exposed; consider vaccination if at risk. |
💊 Management
- Supportive care: rest, oral fluids, nutrition and symptom control.
- 💧 Use oral rehydration solution if vomiting, diarrhoea or dehydration risk.
- 🍷 Avoid alcohol until fully recovered.
- 💊 Avoid unnecessary hepatotoxic drugs; be cautious with paracetamol and check local guidance in significant hepatitis.
- 🤢 Treat nausea/vomiting if needed to maintain hydration.
- 🚑 Admit or urgently refer if acute liver failure, coagulopathy, encephalopathy, severe dehydration or severe systemic illness is suspected.
- 📈 Follow liver blood tests and INR if clinically significant hepatitis or risk factors are present.
🏥 Public Health & Infection Control
- 📢 Hepatitis A is a notifiable disease in the UK.
- 🧼 Emphasise handwashing after toileting and before preparing food.
- 🚽 Use separate towels and careful toilet hygiene where possible.
- 🍽 Avoid preparing food for others while infectious.
- 🏫 Exclusion from work, school or nursery may be needed, especially for food handlers, healthcare workers, nursery staff and young children; follow local health protection advice.
- 🧑🤝🧑 Close contacts may need post-exposure prophylaxis after risk assessment.
💉 Vaccination - Who Should Be Offered It?
- ✈️ Travellers to high or intermediate prevalence countries.
- 🧑🤝🧑 Close contacts of hepatitis A cases after public-health risk assessment.
- ❤️ Gay, bisexual and other men who have sex with men if at ongoing risk.
- 🩺 People with chronic liver disease, because severe hepatitis A is more likely.
- 🧪 People at occupational risk, such as some laboratory workers or sewage workers.
- 🏠 Some people living in institutions or outbreak settings, guided by public health.
- 💉 A second dose is usually needed for long-term protection, depending on vaccine schedule.
🛡 Post-Exposure Prophylaxis
- Mainstay: hepatitis A vaccine for susceptible close contacts where indicated.
- ⏱ Post-exposure prophylaxis is most useful when given as soon as possible, generally within 14 days of exposure.
- Human normal immunoglobulin: may be considered for higher-risk susceptible contacts, such as older adults, immunosuppressed people or those with chronic liver disease.
- 📞 Decisions should be made with local health protection or public health teams.
- 🧪 Consider checking immunity if previous HAV infection or vaccination is likely, but do not delay urgent prophylaxis unnecessarily.
🚑 Fulminant Hepatitis / Acute Liver Failure
- Rare complication, but potentially fatal.
- Higher risk in older adults and people with chronic liver disease, especially chronic HBV or HCV.
- Warning signs include worsening jaundice, prolonged PT/raised INR, hypoglycaemia, encephalopathy and renal impairment.
- Requires urgent hospital assessment and early discussion with a liver unit.
📝 Exam Pearls
- 💩 Hepatitis A spreads faeco-orally.
- 🚫 HAV does not cause chronic hepatitis.
- 🧪 Anti-HAV IgM = acute infection.
- 🛡 Anti-HAV IgG = past infection or vaccination.
- 🟡 Adults are more likely than children to become jaundiced.
- ⚠️ Severe disease is more likely in older adults and chronic liver disease.
- 📢 Hepatitis A is notifiable - involve public health for contacts and outbreaks.
🧠 Teaching Note
Hepatitis A is best understood as an acute immune-mediated hepatitis rather than a chronic viral liver disease.
The virus replicates in the liver and is shed in stool, which explains why patients are infectious before jaundice and why hygiene/contact tracing matters.
The hepatocellular injury is largely caused by the host immune response, giving high ALT/AST, malaise and jaundice.
Unlike HBV and HCV, HAV does not integrate or persist as a chronic infection, so the key risk is acute severity rather than chronic carriage.
📚 References & UK Resources
