Hepatitis A
Acute viral hepatitis — transmission, management and prevention through vaccination
Hepatitis A is an acute viral liver infection caused by the hepatitis A virus (HAV), transmitted via the faecal-oral route through contaminated food, water, or close contact. It is the most common cause of acute viral hepatitis globally. Unlike hepatitis B and C, hepatitis A does not cause chronic liver disease and almost always resolves spontaneously. However, it can rarely cause acute liver failure, particularly in patients with pre-existing liver disease. Prevention through vaccination is highly effective.
Transmission and Risk Factors
Hepatitis A spreads via the faecal-oral route. Contaminated food (shellfish, salads, raw produce) and water are the most common vehicles of transmission. Person-to-person spread occurs through close household or sexual contact, particularly in men who have sex with men (MSM). Travel to endemic areas (South Asia, Africa, Middle East, Central and South America) is a major risk factor for UK residents. Outbreaks can occur in settings of poor sanitation. The virus is shed in faeces for up to 2 weeks before symptoms appear, making early isolation important.
Symptoms and Clinical Course
The incubation period is 15–50 days (average 28 days). The illness is typically self-limiting and resolves within 4–8 weeks. A prodromal phase lasting 1–2 weeks causes flu-like symptoms, fatigue, nausea, vomiting, abdominal discomfort, and loss of appetite. The icteric phase brings jaundice (yellow skin and eyes), dark urine, pale stools, and pruritus. Children under 6 often have asymptomatic infection. Adults experience more severe symptoms and a longer illness. A small proportion have a relapsing or prolonged course lasting up to 6 months. Fulminant hepatitis A causing acute liver failure occurs in under 1% of cases but is more common in those with pre-existing liver disease.
Diagnosis
Hepatitis A is diagnosed by detecting anti-HAV IgM antibodies in serum — these are present at the onset of symptoms and persist for 3–6 months. Anti-HAV IgG indicates past infection or vaccination and provides lifelong immunity. LFTs show markedly elevated ALT (often >1000 IU/L), raised bilirubin, and variable elevation of ALP. Clotting studies (INR) should be checked to identify coagulopathy indicating severe disease. HAV RNA PCR is used in specialist settings to confirm active viraemia and in outbreak investigation.
Management and Prevention
There is no specific antiviral treatment for hepatitis A — management is supportive. Rest, adequate hydration, and avoidance of alcohol and hepatotoxic drugs (including NSAIDs and paracetamol at high doses) during the acute illness are advised. Most patients can be managed at home. Hospital admission is required if there is severe dehydration, vomiting preventing oral intake, signs of acute liver failure (coagulopathy, encephalopathy), or very elevated bilirubin. Patients with pre-existing liver disease should be monitored closely. Return to work or school is safe once jaundice has resolved and the patient feels well. This article has been prepared following careful evaluation of Public Health England guidance and NICE recommendations on hepatitis A management and vaccination.
Vaccination and Public Health
Hepatitis A vaccination provides highly effective protection. The inactivated hepatitis A vaccine (Havrix, Avaxim, VAQTA) gives over 95% protection after a single dose, with a booster at 6–12 months providing long-term (possibly lifelong) immunity. In the UK, vaccination is recommended for: travellers to endemic areas, MSM, people with chronic liver disease (including hepatitis B or C), people who inject drugs, people at occupational risk (sewage workers, healthcare workers in certain settings), and contacts during an outbreak. Post-exposure prophylaxis with the vaccine within 14 days of exposure is effective. Human normal immunoglobulin (HNIG) is used for post-exposure protection in those who cannot receive the vaccine.