Hepatitis A 

 What is Hepatitis A?

Hepatitis A is an acute, self-limited viral infection of the liver caused by the Hepatitis A virus (HAV).

Unlike Hepatitis B or C:

  • ❌ No chronic infection
  • ❌ No carrier state
  • ❌ No cirrhosis from chronicity
  • ❌ No hepatocellular carcinoma

But it can cause fulminant hepatic failure, especially in adults.

 Single serotype = lifelong immunity after infection or vaccination


 Epidemiology

Global Pattern

Region

Pattern

Low-income countries

Early childhood infection (often asymptomatic)

Developed countries

Adult outbreaks

India

Historically high endemicity, now shifting to intermediate

Transmission

  • Feco-oral route
  • Contaminated water
  • Poor sanitation
  • Food handlers
  • Raw shellfish
  • Day-care centers
  • MSM outbreaks
  • Travelers


 Pathogenesis

1️⃣ Ingestion → replication in oropharynx & gut
2️⃣ Viremia
3️⃣ Reaches liver via portal circulation
4️⃣ Replication inside hepatocytes
5️⃣ Immune-mediated cytotoxic T-cell injury
6️⃣ Virus excreted in bile → stool

 Liver injury is immune mediated, not directly cytopathic.


 Incubation Period

  • 15–50 days
  • Average: 28 days


 Clinical Presentation

1️⃣ Asymptomatic Phase (common in children)

<6 years: >70% asymptomatic


2️⃣ Symptomatic Acute Hepatitis (Adults)

🔹 Prodromal (Pre-icteric) Phase

  • Fever
  • Malaise
  • Nausea
  • Vomiting
  • Anorexia
  • Myalgia
  • RUQ discomfort

Duration: 3–7 days


🔹 Icteric Phase

  • Jaundice
  • Dark urine
  • Pale stool
  • Hepatomegaly
  • Pruritus (mild)
  • Fatigue


3️⃣ Convalescent Phase

  • Gradual recovery
  • Fatigue may persist for weeks


 Complications

Complication

Frequency

Prolonged cholestasis

5%

Relapsing hepatitis

10%

Acute liver failure

<1%

Fulminant hepatic failure

Rare but serious

Risk factors for severe disease:

  • Age >50
  • Chronic liver disease
  • Alcohol use
  • Immunocompromised


 Acute Liver Failure Due to HAV

Features:

  • INR >1.5
  • Encephalopathy
  • Jaundice

Higher mortality in:

  • Elderly
  • Underlying liver disease


 Laboratory Findings

LFT Pattern

Parameter

Finding

AST/ALT

Markedly elevated (1000–3000 IU/L)

ALT > AST

Typical

Bilirubin

Elevated

ALP

Mildly elevated

INR

Normal unless severe


Specific Diagnosis

Test

Interpretation

Anti-HAV IgM

Acute infection

Anti-HAV IgG

Past infection or immunity

HAV RNA PCR

Rarely needed

 IgM detectable at symptom onset → disappears in 3–6 months


 Differential Diagnosis

  • Hepatitis B
  • Hepatitis E
  • Drug-induced liver injury
  • Autoimmune hepatitis
  • Ischemic hepatitis
  • Obstructive jaundice


 Management

 No Specific Antiviral Therapy

Treatment is supportive

General Measures

  • Rest
  • Hydration
  • Avoid alcohol
  • Avoid hepatotoxic drugs (e.g., paracetamol overdose)

Hospitalization Indications

  • Severe vomiting
  • INR rising
  • Encephalopathy
  • Severe dehydration
  • Acute liver failure


 Prevention

1️⃣ Vaccination

  • Inactivated HAV vaccine
  • 2 doses (0 and 6 months)
  • 95% seroconversion
  • Lifelong immunity

Available vaccines:

  • Havrix
  • Vaqta


2️⃣ Post-Exposure Prophylaxis (PEP)

Age

Recommendation

<40 years

Vaccine within 14 days

>40 years

Vaccine ± Immunoglobulin

Immunocompromised

Vaccine + IG

Chronic liver disease

Vaccine + IG


3️⃣ Sanitation

  • Safe water
  • Hand hygiene
  • Food safety
  • Avoid raw shellfish

 Comparison: Hepatitis A vs Hepatitis E

Feature

HAV

HEV

Chronicity

No

Rare

Pregnancy risk

Low

High mortality

Vaccine

Yes

Limited availability

Transmission

Feco-oral

Feco-oral