Hepatitis refers to inflammation of the liver — the organ responsible for filtering toxins from the blood, producing proteins essential for clotting and immunity, and processing nutrients from digestion. Hepatitis can be caused by viral infection, alcohol, certain medications, or the body's own immune system, but the three viral forms — hepatitis A, B, and C — are collectively the most common cause worldwide, and the focus of this page.
Despite sharing a name, hepatitis A, B, and C are three genuinely different viruses, spread in different ways, carrying very different long-term risks, and requiring different approaches to prevention and treatment. Hepatitis A causes a short, self-limiting illness that never becomes chronic. Hepatitis B and C, by contrast, can become chronic infections that silently damage the liver over decades, making them leading causes of cirrhosis and liver cancer worldwide — and a particularly relevant concern in Singapore and the wider region, where hepatitis B has historically been more common than in Western countries.
How Hepatitis A, B, and C Differ
- Hepatitis A: Spread through contaminated food or water, or close contact with an infected person — the “faecal-oral” route. Causes an acute, short-term illness lasting several weeks, after which the body clears the virus completely and develops lifelong immunity. Never becomes a chronic infection. A safe, effective vaccine is available.
- Hepatitis B: Spread through blood, and through contact with semen or vaginal secretions, including from mother to baby during childbirth. The most common cause of chronic viral liver disease worldwide. Most adults who are infected clear the virus, but infection acquired at birth or in early childhood becomes chronic in the large majority of cases. A safe, effective vaccine is available.
- Hepatitis C: Spread primarily through blood-to-blood contact, most commonly through sharing needles or injecting equipment. The majority of people who are infected go on to develop chronic infection. No vaccine is currently available, but modern antiviral medication now cures the large majority of cases.
Acute vs. Chronic Hepatitis: Why the Distinction Matters
Every case of viral hepatitis begins as an acute infection — the period during which the virus first establishes itself and the immune system mounts its initial response. What happens after this initial phase is where the three viruses diverge sharply, and it is this divergence, more than the acute illness itself, that determines long-term health risk.
Hepatitis A is always acute and self-limiting — once the initial illness resolves, typically within a few weeks to a couple of months, the infection is gone for good. Hepatitis B and C, however, can become chronic, meaning the virus persists in the body for years or decades after the initial infection, often without causing any noticeable symptoms during this time. This chronic, ongoing low-grade inflammation is what gradually damages liver tissue, and it is why hepatitis B and C — not hepatitis A — are the forms of viral hepatitis associated with long-term complications such as cirrhosis and liver cancer.
Hepatitis B and C: The Silent Path to Cirrhosis and Liver Cancer
Chronic hepatitis B and C deserve particular attention because they very often cause no symptoms at all for years, even decades, while quietly causing progressive liver damage in the background. Many people living with chronic hepatitis B or C feel completely well and are only diagnosed incidentally, through routine blood tests or screening, long after the infection was first acquired.
Over time, this silent inflammation can lead to fibrosis (scarring) of the liver, progressing in some individuals to cirrhosis — extensive, irreversible scarring that impairs liver function — and, in a proportion of those with cirrhosis, to hepatocellular carcinoma, the most common form of liver cancer. This is why people diagnosed with chronic hepatitis B or C, particularly those with cirrhosis, are recommended regular liver surveillance, typically combining blood tests and liver ultrasound, so that any early signs of disease progression or cancer are caught while still highly treatable.
This silent quality also explains why testing matters more than symptom-watching for hepatitis B and C. Someone can carry either virus for years, feel entirely healthy, and unknowingly pass it on to others or allow liver damage to progress — which is why screening for at-risk individuals, rather than waiting for symptoms, is central to hepatitis B and C control.
Symptoms of Hepatitis
When symptoms of acute hepatitis do occur — most commonly with hepatitis A, and less consistently with new hepatitis B or C infection — they typically include:
- Fatigue and general tiredness
- Nausea, and reduced appetite
- Abdominal pain or discomfort, particularly over the liver on the right side
- Dark urine and pale, clay-coloured stools
- Jaundice — yellowing of the skin and eyes
- Fever
- Joint pain
Risk Factors for Hepatitis
- Travel to, or residence in, areas with lower food and water hygiene standards (hepatitis A)
- Sharing needles or injecting equipment (hepatitis B and C)
- Unprotected sexual contact with an infected partner (hepatitis A and B)
- Being born to a mother with chronic hepatitis B, without appropriate birth-dose prevention
- Healthcare work involving exposure to blood or bodily fluids
- Receiving blood transfusions or organ transplants prior to the introduction of modern blood screening
- Long-term haemodialysis
- Having multiple sexual partners, or a partner with chronic hepatitis B
- Living in a household with someone who has chronic hepatitis B
How Hepatitis Is Diagnosed
- Liver Function Tests: Blood tests measuring liver enzymes and other markers of liver function, indicating whether liver inflammation or damage is present, though not identifying which virus is responsible.
- Hepatitis Serology Panel: Specific blood tests for each virus — including antibodies and viral antigens — that confirm which type of hepatitis is present, whether the infection is current or past, and, for hepatitis B, whether it has become chronic.
- Hepatitis C RNA Test: Confirms active hepatitis C infection and measures viral load, since a positive antibody test alone only indicates past exposure and does not confirm the virus is still present.
- Liver Imaging (Ultrasound, FibroScan): Assesses the liver for structural changes, scarring (fibrosis), and, in surveillance for chronic carriers, early signs of liver cancer. FibroScan specifically measures liver stiffness as a marker of fibrosis without requiring a biopsy.
- Liver Biopsy: Occasionally used to assess the extent of liver damage in more detail when non-invasive tests do not give a clear enough picture, though its use has decreased with the availability of imaging-based alternatives.
Preventing Hepatitis
- Get vaccinated against hepatitis A and B if you have not already been vaccinated, particularly before travel to areas with higher rates of infection
- Practise good hand hygiene and food safety, particularly when travelling
- Never share needles, syringes, or other injecting equipment
- Practise safer sex, including barrier protection, particularly with new or multiple partners
- Avoid sharing personal items that may carry traces of blood, such as razors or toothbrushes
- If you are pregnant, get tested for hepatitis B, since timely vaccination and treatment can prevent transmission to your baby
- If you have risk factors for hepatitis B or C, ask your doctor about screening, even without symptoms — early detection meaningfully changes long-term outcomes for both
