Hepatitis A (Acute HAV Infection)

Hepatitis A is an acute viral infection of the liver caused by the hepatitis A virus (HAV). It is one of the most common vaccine-preventable infections worldwide, spread primarily through contaminated food or water or close contact with an infected person. Unlike hepatitis B and C, hepatitis A does not cause chronic liver disease — almost everyone recovers fully, and infection provides lifelong immunity.

Illness ranges from very mild or completely asymptomatic — particularly in young children — to a debilitating illness lasting several months in adults. Acute liver failure is rare but possible, particularly in people with pre-existing liver disease or those who are older.

How hepatitis A spreads

HAV is transmitted by the fecal-oral route — meaning the virus is shed in the stool of infected people and enters a new host through ingestion. Transmission occurs through:

• Eating food prepared by an infected person who did not wash their hands adequately
• Drinking contaminated water or eating raw shellfish (particularly oysters) from contaminated water
• Close personal contact with an infected person, including household contact or sexual contact
• Travel to regions where hepatitis A is endemic and sanitation standards differ

HAV is not transmitted through casual contact, coughing, sneezing, or sharing utensils with someone who is not actively infectious. The virus is highly stable in the environment and can survive on surfaces and in water for extended periods.

The infectious period begins approximately two weeks before symptoms appear and continues for about one week after the onset of jaundice — meaning people can transmit the virus before they know they are infected.

Symptoms

Symptoms of hepatitis A typically appear two to six weeks after exposure (the incubation period averages around 28 days). Not everyone develops noticeable symptoms — children under six years old are often asymptomatic, while older children and adults are more likely to have symptomatic illness.

When symptoms occur, they typically develop in two phases:

Prodromal phase (first 1–2 weeks)

• Sudden onset of fatigue and malaise
• Loss of appetite and nausea
• Vomiting and abdominal discomfort, particularly in the right upper quadrant
• Low-grade fever
• Muscle aches
• Dark urine — often the first specific sign noticed

Icteric phase (jaundice phase)

• Jaundice — yellowing of the skin and the whites of the eyes
• Pale or clay-coloured stools
• Itching (pruritus)
• Symptoms from the prodromal phase may improve once jaundice appears

Most people feel significantly better within two to three months. A minority experience a relapsing or prolonged course lasting up to six months, with symptoms recurring after initial improvement.

Seek medical attention promptly if you develop:

• Progressive or deepening jaundice
• Confusion, extreme drowsiness, or personality change
• Significant abdominal swelling
• Unusual bleeding
• Inability to tolerate any food or fluids

These features may indicate rare but serious complications including acute liver failure.

Diagnosis

Hepatitis A is diagnosed with a blood test. The key tests are:

Hepatitis A Ab, IgM (anti-HAV IgM) This is the diagnostic test for acute infection. IgM antibodies appear within a week of symptom onset and are usually detectable for up to six months. A reactive IgM result in someone with compatible symptoms confirms acute hepatitis A infection.

Hepatitis A Ab, Total (anti-HAV total) This test detects both IgM and IgG antibodies. A reactive total result with a non-reactive IgM indicates past infection or successful vaccination — not current illness. It is used to assess immune status rather than diagnose active disease.

Liver function tests ALT and AST are markedly elevated during acute infection — often ten to forty times the upper limit of normal. Bilirubin rises as jaundice develops. ALP and GGT may also be elevated. These markers are used to monitor severity and track recovery.

Treatment

There is no specific antiviral treatment for hepatitis A. Management is supportive:

• Rest — fatigue is the dominant symptom; activity should be guided by how the person feels
• Hydration and nutrition — adequate fluid intake is important, particularly if nausea and vomiting are present; small, frequent meals are often better tolerated than large ones
• Avoid alcohol and hepatotoxic medications — the liver is already under stress and anything that adds to that burden should be avoided during illness and recovery
• Symptom management — antiemetics can help with nausea; pruritus from cholestasis may require specific treatment

Most people recover fully without hospitalisation. Hospital admission is considered for people who cannot maintain hydration, have significantly impaired liver synthetic function (raised INR, falling albumin), show signs of encephalopathy, or have underlying liver disease that increases the risk of complications.

Recovery and immunity

The great majority of people with hepatitis A recover completely within two to three months with no lasting liver damage. HAV does not cause chronic infection — once the acute illness resolves, the virus is cleared from the body. Infection produces lifelong immunity: a person who has had hepatitis A cannot be reinfected.

After recovery, IgG antibodies remain detectable in the blood for life. A reactive Hepatitis A Ab Total result with a non-reactive IgM — found on a routine blood panel long after any illness — usually reflects this past immunity.

Prevention and vaccination

Hepatitis A is highly preventable. The hepatitis A vaccine is safe, effective, and provides long-lasting protection. It is given as a two-dose series and is recommended for travellers to endemic regions, people with chronic liver disease, those at occupational risk, and as part of routine childhood immunisation schedules in many countries.

Post-exposure prophylaxis with the vaccine (or in some cases immunoglobulin) can prevent illness if given promptly after a known exposure — ideally within two weeks.

General hygiene measures also reduce transmission: thorough handwashing, safe food handling practices, and avoiding raw shellfish from unverified sources are the most important precautions during travel or in outbreak settings.

FAQ

Is hepatitis A serious? For most healthy adults, hepatitis A causes a self-limiting illness that resolves fully within a few months. It is rarely life-threatening. However, it can cause prolonged, debilitating illness, and people with pre-existing liver disease, older adults, and those who are immunocompromised face a higher risk of severe disease. Acute liver failure occurs in less than 1% of cases overall but is more common in these higher-risk groups.

Does hepatitis A go away on its own? Yes, in virtually all cases. Hepatitis A is a self-limiting infection — the immune system clears the virus and the liver recovers without specific treatment. Supportive care helps manage symptoms during recovery. Unlike hepatitis B and C, there is no risk of the infection becoming chronic.

Can you get hepatitis A more than once? No. Infection with hepatitis A produces lifelong immunity. A person who has recovered from hepatitis A — or who has been vaccinated — cannot be reinfected.

Related biomarkers

Key lab markers in hepatitis A include Hepatitis A Ab, IgM (diagnostic for active infection), Hepatitis A Ab, Total (immunity assessment), ALT, AST, and bilirubin (liver function monitoring during illness and recovery). Tracking these results over time in HealthMatters can help document the course of recovery and confirm return to normal liver function.