Hepatitis B
Hepatitis B is a viral liver infection caused by the hepatitis B virus (HBV). It can present as an acute illness, but importantly, HBV can also cause chronic (long-term) infection that may lead to serious complications like cirrhosis (scarring of the liver) and liver cancer. Hepatitis B is a major global health problem, with hundreds of millions chronically infected worldwide. The virus is transmitted through blood and bodily fluids. Thankfully, a very effective vaccine exists to prevent HBV infection.
Symptoms
Acute hepatitis B : Many people have no symptoms when first infected (especially children). If symptoms do occur, they typically develop 1 to 4 months after exposure. Acute HBV infection can cause symptoms similar to other hepatitis types:
- Jaundice : Yellowing of the skin and eyes, often accompanied by dark urine and pale stools.
- Flu-like symptoms : Fatigue, fever, loss of appetite, nausea, vomiting.
- Abdominal pain : Stomach pain, diarrhea, and sometimes joint pain or a skin rash.
- Joint pains or rash (less common).
Symptoms may last a few weeks to a few months. Most healthy adults will clear the virus and recover from acute hepatitis B infection spontaneously. A small proportion can develop fulminant hepatitis (a sudden, severe liver failure), which is life-threatening, but this is rare.
Causes
Hepatitis B is caused by the hepatitis B virus, which is transmitted through blood or other body fluids. Major modes of HBV transmission include:
- Mother-to-child (perinatal): The most common route globally. Babies born to an HBV-infected mother can become infected during childbirth. Without preventive measures, 90% of these infants will develop chronic infection.
- Childhood exposure: In highly endemic regions, HBV often spreads between young children through close household contact or minor breaks in the skin.
- Unprotected sexual contact: HBV can spread via semen, vaginal fluids, or blood during sex with an infected partner.
- Unsafe injections or medical procedures: Reuse of contaminated needles/syringes, or accidental needlesticks can transmit HBV. This includes sharing needles for IV drug use, or even non-sterile tattooing/piercing.
- Blood transfusions or organ transplants: In the past, this was a risk, but now blood and organ donations are rigorously screened for HBV in most countries.
HBV is much more infectious than HIV. It is not spread through casual contact like hugging, kissing, or sharing food, nor through coughing or sneezing. However, sharing personal items that may have microscopic blood (razors, toothbrushes) could potentially spread HBV and should be avoided.
One critical factor is the age at infection: Infections in infancy or early childhood very often become chronic (the immune system fails to clear the virus), whereas infections acquired in adulthood are cleared in >90–95% of cases. This is why vaccinating infants and children is so important.
Diagnosis
Hepatitis B is diagnosed with blood tests. Key tests include:
- HBsAg (Hepatitis B surface antigen): A protein on the virus; if positive, it indicates an active HBV infection (acute or chronic).
- HBsAb (Hepatitis B surface antibody): Indicates immunity to HBV (from vaccine or recovered infection).
- HBcIgM (IgM antibody to core antigen): Indicates recent infection (used to diagnose acute hepatitis B).
- HBV DNA test: Measures the amount of virus in the blood (viral load), mainly used in chronic HBV to guide treatment.
Liver function tests (ALT, AST) will usually be elevated in acute hepatitis or active chronic hepatitis, signaling liver inflammation. Doctors may also evaluate liver damage with imaging (ultrasound, FibroScan) or occasionally a liver biopsy if needed, especially in chronic cases to assess fibrosis.
Treatment
Acute hepatitis B: There is no specific antiviral treatment for acute HBV infection – the immune system usually clears the virus on its own. Supportive care (rest, fluids, nutrition) is the main approach. Patients are monitored to ensure liver tests return to normal. Severe acute hepatitis (fulminant hepatic failure) is rare; if it occurs, antiviral therapy and intensive care support (or emergency liver transplant) may be necessary.
Chronic hepatitis B: Treatment is aimed at preventing liver damage and complications. Not everyone with chronic HBV needs immediate medication – it depends on levels of the virus and liver enzyme tests or evidence of liver injury. The main treatments are antiviral medications that suppress HBV replication:
- Oral antivirals (first-line): Potent daily medications such as tenofovir or entecavir. They can lower the virus to undetectable levels in most patients, greatly reducing liver damage risk. Treatment may be long-term (often lifelong) because these drugs suppress but usually do not eliminate the virus completely.
- Interferon injections (pegylated interferon): Used in some cases to stimulate the immune system to fight HBV. This is a finite-duration treatment (6–12 months) and can sometimes clear the virus. However, it is not suitable for all patients due to significant side effects.
FAQs
For acute hepatitis B, many adults clear the virus on their own and recover fully. However, for chronic hepatitis B, there is currently no complete cure (no treatment guarantees total eradication of the virus from the liver). The available antiviral treatments control the virus and stop progression of disease, but they usually do not eliminate HBV entirely from the body. That means most chronically infected patients need long-term or lifelong therapy to keep the virus suppressed. Researchers are working on potential cures, but as of now, management is about control, not cure, for chronic hepatitis B.
It depends on the age at infection. If an adult catches HBV, over 90% will clear the virus and not become chronic carriers. Only a small percentage (under 5%) of adult-acquired cases become chronic. In contrast, infants who get infected (for example, via mother-to-child transmission at birth) have about a 90% chance of developing chronic hepatitis B. Young children (under 5) also have a high risk of chronic infection if infected. This is why the HBV vaccine at birth is crucial – to prevent these early-life infections that would likely become chronic.
Chronic HBV infection can range from an “inactive” carrier state (low virus levels, normal liver tests) to active chronic hepatitis that scars the liver. Over years or decades, chronic hepatitis B can lead to cirrhosis (extensive scarring) and even liver failure. It also significantly increases the risk of hepatocellular carcinoma (primary liver cancer) – in fact, hepatitis B is a leading cause of liver cancer worldwide. The good news is that effective treatment and regular monitoring can greatly reduce these risks. Many people with chronic HBV, especially if properly managed, live long healthy lives. But untreated, it’s a serious disease that warrants medical care.
Yes – a very effective vaccine exists. The hepatitis B vaccine is part of routine childhood immunizations in most countries and is recommended for all infants. It’s also recommended for unvaccinated adults at risk (such as healthcare workers, people with multiple sexual partners, injection drug users, those with an HBV-infected household member, and travelers to high-risk areas). The vaccine series induces protective antibodies in >95% of people and provides long-term (possibly lifelong) immunity. In fact, widespread vaccination has dramatically lowered new hepatitis B infections. If you haven’t been vaccinated, ask your doctor – it’s a safe and effective way to prevent this disease.
If you’re HBV-positive, there are several important precautions: Ensure close contacts (sexual partners, family members) are tested and vaccinated if not already immune. Practice safe sex (use condoms) until partners are confirmed immune. Do not share personal items like razors, toothbrushes, nail clippers (they can have tiny blood traces). Cover open cuts and dispose of blood-stained items carefully. Do not donate blood or organs. These measures, plus your contacts being vaccinated, will prevent transmission. Mothers with HBV can still have healthy babies – doctors will give the newborn HBV vaccine and a dose of HBIG (hepatitis B immune globulin) at birth to prevent infection. With these steps, the risk of passing HBV to others can be minimized.