Hepatitis A

Background

Hepatitis A is an infection of the liver caused by the hepatitis A virus (HAV). HAV is an RNA virus. Transmission occurs primarily through the faecal–oral route, either via person-to-person contact or by consuming contaminated food or water. There is no chronic persistent state, and chronic liver damage does not occur.

Epidemiology

Improved standards of living and hygiene have seen cases of hepatitis A infection in the UK drop significantly over recent decades. The number of laboratory reports of hepatitis A in England and Wales has fallen from 1,318 in 1997 to 274 in 2021. Occasional outbreaks do occur and may see increased number of reports cases in outbreak years.

Transmission

HAV is primarily transmitted via the faecal–oral route through person-to-person spread or contaminated food or drink. Foodborne outbreaks are rare but have been reported following ingestion of certain shellfish, contaminated fruit and vegetables. Note faecal shedding of HAV is highest in the 2 weeks before symptom onset i.e. this is the period where the patient is at their most infectious. Once jaundice appears, faecal shedding declines and typically ceases within a week.

Average incubation period of hepatitis A is approximately 28 days (range 15 to 50 days)

Clinical Features

The disease is generally mild, but severity increases with age. Asymptomatic disease is common in children. Jaundice may occur in 70–80% of those infected as adults. Fulminant hepatitis can occur but is rare. The overall case–fatality ratio is low but is greater in older patients and those with pre-existing liver disease. There is no chronic persistent state, and chronic liver damage does not occur.

The clinical phases of hepatitis A are no different to other forms of hepatitis and are summarised below:

Investigations & diagnosis

Diagnosis is confirmed by detecting HAV-specific IgM antibodies in the blood.

HAV-IgM antibodies are typically present 5–10 days before the onset of symptoms, peak within a month of illness, and usually remain positive for 45–60 days but can persist for up to 12 months.

HAV-IgG levels begin to rise soon after HAV-IgM levels and stay elevated throughout the person's lifetime. This may be tested to ascertain a patients past infection and immunity status.

LFT's are typically performed. Transaminase levels may reach more than 10,000 units/L, although there is little correlation between level and disease severity. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are usually between 500 and 10,000 IU/L. Bilirubin is often elevated (typically >85). Alkaline phosphatase is typically < 2x the upper limit of normal. but higher if there is cholestasis.
Prothrombin time may be prolonged to 3 seconds or more.

Risk factors

People at high risk of hepatitis A infection include:

• Travellers to areas with a high or intermediate prevalence
• Men who have sex with men
• Injecting drug users and their close contacts
• People with clotting factor disorders
• People at occupational risk (e.g. laboratory workers, staff of large residential institutions, sewage workers, and people who work with primates).

Management:
There is no specific antiviral treatment for hepatitis A. Management usually involves supportive care focused on symptom relief. Patients should be advised on avoidance of alcohol and hepatotoxic drugs in the acute phases of the illness.

Hospital admission is rarely required unless there is evidence of acute liver failure or other complications.

Prevention:

Good hygiene, principally thorough hand washing, is the cornerstone of prevention.

Vaccination is also an effective method of preventing hepatitis A infection. In the UK, hepatitis A vaccination is not part of the routine vaccination schedule but is recommended for individuals with the following underlying medical conditions:

• Chronic liver conditions
• Haemophilia

It may also be offered to people at high risk including:

• Travellers to areas where hepatitis A is common.
• Men who have sex with men.
• People who inject drugs.
• Those who may be exposed through their work (e.g., laboratory staff, sewage workers).
• Close contacts of confirmed or suspected cases

The vaccine is usually given as a single dose, followed by a booster 6–12 months later to provide long-term protection.


Human normal immunoglobulin (HNIG) may provide short term immunity and should be considered for use on close contacts of cases if they meet certain criteria. Contact tracing and management of contacts will typically be perfomed by the local HPU.