Key Facts

Hepatitis A is an acute, self-limiting liver infection that does not cause chronic hepatitis. It is a notifiable disease in the UK. Prevention through vaccination and public health measures is the primary strategy.

Epidemiology

~350 cases per year in the UK (most travel-associated). Endemic in Sub-Saharan Africa, South/Southeast Asia, Central America. UK is low-endemicity — most adults are susceptible. Outbreaks occur in MSM communities, people who inject drugs, and institutional settings.

Aetiology

• Hepatitis A virus (HAV): non-enveloped RNA virus (Picornaviridae family)
• Transmission: faecal-oral — contaminated food (shellfish, salad), water, person-to-person (household, sexual contact), blood-borne (rare)
• Risk groups: travellers to endemic areas, MSM, PWID, household contacts, occupational (sewage workers)

Pathophysiology

HAV replicates in hepatocytes. Liver damage is primarily immune-mediated (CD8+ T-cell response) rather than direct viral cytopathic effect. The inflammatory response causes hepatocyte necrosis and cholestasis. Viral shedding in stool begins 1-2 weeks before symptom onset and peaks around jaundice onset — hence transmission occurs before diagnosis. Complete viral clearance occurs and there is no chronic carrier state.

Prodromal Phase (1-2 weeks)

• Malaise, fatigue, anorexia, nausea
• Low-grade fever, myalgia
• RUQ discomfort

Icteric Phase (2-6 weeks)

• Jaundice (dark urine, pale stools, pruritus)
• Hepatomegaly (tender)
• Prodromal symptoms often improve as jaundice appears
• Splenomegaly (~15%)

Recovery Phase

• Gradual resolution over weeks to months
• Fatigue may persist for months

Atypical Presentations

• Subclinical/anicteric: common in children (<6 years — 70% asymptomatic)
• Cholestatic hepatitis: prolonged jaundice (>3 months) — good prognosis
• Relapsing hepatitis: symptoms recur after apparent recovery (~10%)
• Fulminant hepatic failure: rare (<0.5%) but potentially fatal; more common in elderly and those with pre-existing liver disease

Red Flags

• Encephalopathy (confusion, asterixis) — fulminant failure
• INR >1.5 with rising bilirubin
• Rapidly shrinking liver size
• Renal failure

Bedside

• History: travel, food exposure, contacts, sexual history, occupation

Bloods

• Anti-HAV IgM: diagnostic of acute infection (positive for up to 6 months)
• Anti-HAV IgG: indicates past infection or vaccination (lifelong immunity)
• LFTs: markedly raised ALT/AST (often >1000 IU/L); raised bilirubin; ALP variably raised
• INR/PT: normal in most; raised in severe/fulminant disease (poor prognostic sign)
• FBC: mild lymphopaenia, sometimes leucopaenia
• U&Es: renal function (hepatorenal syndrome in fulminant)

Imaging

• USS abdomen: exclude biliary obstruction; may show hepatomegaly

Special Tests

• HAV RNA (PCR): confirms viraemia; rarely needed clinically (IgM sufficient)
• Liver biopsy: NOT routinely indicated; shows portal and periportal inflammation with hepatocyte necrosis
• King's College Criteria: for assessing need for liver transplant in fulminant failure

Non-pharmacological

• Supportive care: rest, adequate hydration, avoid alcohol, avoid hepatotoxic drugs
• Infection control: handwashing, food hygiene; infectious until 7 days after jaundice onset
• Notify PHE: HAV is a notifiable disease under the Health Protection (Notification) Regulations 2010
• Contact tracing: household and sexual contacts

Pharmacological

• No specific antiviral treatment for hepatitis A
• Symptomatic relief: anti-emetics (cyclizine, ondansetron), cholestyramine for pruritus, paracetamol for pain (avoid if severe liver impairment)
• Post-exposure prophylaxis: HAV vaccine within 14 days of exposure for close contacts (effective if given early); ± immunoglobulin (HNIG) if immunosuppressed or chronic liver disease

Surgical/Interventional

• Liver transplantation: for fulminant hepatic failure meeting King's College Criteria (very rare)

Referral Criteria

• Hepatology referral if: INR >1.5, encephalopathy, worsening liver function, prolonged cholestasis
• Public health notification: mandatory for all cases
• Liver transplant centre: if fulminant hepatitis

Hepatitis A is self-limiting in >99% of cases. No chronic hepatitis, no carrier state. Complete recovery with lifelong immunity. Fulminant hepatic failure occurs in <0.5% overall but ~1-2% in those >50 years or with pre-existing liver disease. Mortality from fulminant HAV is ~50% without transplant. Cholestatic and relapsing variants have good prognosis. Return to normal activities typically within 2-6 weeks.

Hepatitis A Serology Interpretation

HAV Vaccination