Hepatitis A
Summary
Hepatitis A is an acute, self-limiting viral liver infection caused by the Hepatitis A Virus (HAV), an RNA Picornavirus. It is transmitted via the faecal-oral route, typically through contaminated water, food (shellfish/berries), or person-to-person contact. Unlike Hepatitis B and C, it never causes chronic liver disease. [1,2]
Clinical Pearls
Cigarette Aversion: A surprisingly specific prodromal symptom. Smokers will suddenly lose their taste for tobacco days before the jaundice appears.
The "Filter Feeder" Risk: Bivalve molluscs (Oysters, Mussels, Clams) filter huge volumes of water. If the water is contaminated with sewage, the virus concentrates in their flesh. Eating raw/undercooked shellfish is a classic vector.
Post-Exposure Prophylaxis: Unlike many viruses, the Hepatitis A vaccine works after exposure. If given within 14 days to contacts, it can prevent or attenuate the disease (active immunisation).
Demographics
- Global: Endemic in developing nations (most children infected by age 10, often asymptomatic).
- Imported: Major cause in West is travel to endemic areas.
- Outbreaks: Institutional (nurseries), MSM community, IDU (IV drug users).
Transmission
- Faecal-Oral: Primary route.
- Sexual: Oro-anal contact (rimming).
- Blood: Rare (viraemia is short).
Mechanism
- Ingestion: Virus enters gut -> Portal vein -> Liver.
- Replication: Replicates in hepatocytes. excreted in bile -> stool.
- Damage: The virus is not directly cytopathic. The damage is caused by the host's CD8+ T-Cell response killing the infected hepatocytes.
- Clearance: IgG antibodies develop, providing lifelong immunity.
Incubation Period
Stages
- Prodrome (Pre-icteric): Flu-like. Malaise, Myalgia, Nausea, Vomiting, RUQ pain. Distaste for cigarettes.
- Icteric Phase: Dark urine (bilirubinuria), Pale stools (cholestasis), Jaundice (sclera/skin), Pruritus.
- Convalescence: Slow recovery (weeks to months).
Age Dependence
- Jaundice: Scleral icterus.
- Hepatomegaly: Tender, smooth liver edge.
- Splenomegaly: Occurs in 15%.
- Lymphadenopathy: Cervical nodes (rare).
Serology (The Key)
- IgM Anti-HAV: Positive = Acute Infection. (Persists for 3-6 months).
- IgG Anti-HAV: Positive = Past Infection or Vaccination. (Lifelong immunity).
Biochemistry
- LFTs:
- ALT/AST: Massive elevation (>1000 IU/L). Hepatocellular pattern.
- Bilirubin: Mixed Direct/Indirect elevation.
- ALP: Mild elevation.
- Clotting: Check INR. Prolongation >1.5 suggests Fulminant Failure.
Management Algorithm
ACUTE HEPATITIS A DIAGNOSED
(IgM Positive)
↓
ASSESS SEVERITY (ALF Check)
- Encephalopathy?
- INR > 1.5?
┌─────────┴─────────┐
YES NO
↓ ↓
ADMIT LIVER SUPPORTIVE CARE
UNIT (Urgent) (Home)
↓ ↓
TRANSPLANT - Rest
LISTING? - Fluids
- Avoid Alcohol
↓
PUBLIC HEALTH
- Notify Authority
- Vaccinate Contacts
(less than 14 days)
Supportive Care
- Rest: Fatigue is profound.
- Diet: Low fat if nauseous. High carbohydrate.
- Alcohol: Strict avoidance during acute phase.
- Drugs: Avoid hepatotoxins (Paracetamol, Statins).
- Itch: Cholestyramine or Antihistamines.
Prevention (Vaccine)
- Havrix / Avaxim: Formalin-inactivated virus.
- Regimen: Dose at 0 and 6-12 months.
- Efficacy: >95%. Protection lasts >25 years.
- Indications: Travellers, CLD patients, MSM, IVDU, sewage workers.
- Fulminant Hepatic Failure: Rare (less than 0.5% overall, but 3% in >50s). High mortality.
- Cholestatic Hepatitis: Prolonged jaundice/itch (>3 months). Resolves eventually.
- Relapsing Hepatitis: 10% have a "second wave" of symptoms weeks later. Benign.
- Extra-hepatic: Rash, Arthralgia, Glomerulonephritis (immune complex).
- Mortality: Extremely low (less than 0.1%) in healthy children.
- Chronic Liver Disease: NEVER occurs.
- Carrier State: Does NOT exist.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| The Green Book (Ch 17) | UK HSA | Vaccination protocols for pre- and post-exposure. |
| Management of ALF | EASL | Criteria for referral to transplant centre. |
Landmark Evidence
1. The "Super-Spreader" Effect
- Studies confirm that asymptomatic children are the main vector in community outbreaks, spreading virus to adults who then get sick.
What is Hepatitis A?
It is a virus that causes temporary inflammation of the liver. It is usually caught from contaminated food or water (often abroad) or from close contact with someone infected.
Is it serious?
For most people, it feels like a bad flu with jaundice (turning yellow). It makes you feel very tired and sick for a few weeks, but your body fights it off completely. It does not stay in your system like Hepatitis B or C.
Can I give it to my family?
Yes. You are infectious for about a week after the jaundice starts. You must wash your hands meticulously after the toilet and must not prepare food for others. We can give your family a vaccine now to stop them catching it.
Do I need medicine?
There is no specific antiviral pill. The treatment is rest and fluids. Your liver knows how to heal itself, but it needs time. Avoid alcohol completely while you are recovering.
Primary Sources
- UK Health Security Agency. Hepatitis A: the green book, chapter 17. 2020.
- European Association for the Study of the Liver (EASL). Clinical Practice Guidelines on the management of acute (fulminant) liver failure. J Hepatol. 2017.
Common Exam Questions
- Serology: "IgM Negative, IgG Positive?"
- Answer: Past infection or Immunised.
- Transmission: "Vector of transmission?"
- Answer: Faecal-Oral.
- Complication: "Does it cause cancer?"
- Answer: No (no chronic state).
- Travel: "Unvaccinated traveller less than 14 days pre-departure?"
- Answer: Give vaccine (seroconversion happens quickly).
Viva Points
- Why notify Public Health?: Because it causes outbreaks. They need to trace the restaurant/source to prevent mass infection.
- Alcohol: Why avoid it? The liver enzymes (CYP450 etc) are down-regulated during inflammation. Alcohol is directly toxic and will retard recovery.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.