Hepatitis B.Care & specialists in New Zealand

Hepatitis B is a viral infection of the liver caused by hepatitis B virus (HBV), a DNA virus transmitted through blood, sexual contact, and from mother to child. Most adults clear acute infection, but 90% of infected infants and 25-50% of young children develop chronic infection that can lead to cirrhosis and liver cancer.

HBV is transmitted through blood, semen, and other body fluids. The dominant routes are mother-to-child at birth, sexual contact, shared needles or razors, and unsterile medical or tattoo procedures. HBV is roughly 100 times more transmissible per exposure than HIV. It is not spread by casual contact, kissing, or breastfeeding without nipple trauma.

Acute hepatitis B is cleared spontaneously in over 95% of immunocompetent adults. Chronic hepatitis B can be effectively controlled but not yet fully cured. Oral antivirals (tenofovir, entecavir) suppress the virus in over 95% of patients and prevent cirrhosis and HCC, but functional cure (HBsAg loss) is uncommon.

Two-thirds of acute infections are asymptomatic. The remaining third have fatigue, fever, nausea, abdominal pain, dark urine, and jaundice over 1-3 months. Chronic infection is usually silent for decades until cirrhosis or HCC develops, which can produce fatigue, ascites, jaundice, encephalopathy, or weight loss.

Yes. The recombinant HBsAg vaccine, available since 1982, induces protective antibody in over 95% of healthy infants and adults after three doses (or two doses with Heplisav-B in adults). WHO recommends universal birth-dose vaccination followed by completion of the infant schedule. Protection is durable, with no booster needed for healthy adults.

No. HBV is not spread by casual contact, hugging, kissing, or sharing utensils. Transmission requires exposure to infected blood or body fluids — primarily through sexual contact, shared needles, unsterile medical procedures, or mother-to-child during childbirth.

Hepatitis B surface antigen (HBsAg) is a protein on the outer surface of the hepatitis B virus. Its presence in blood indicates current HBV infection — acute (less than 6 months) or chronic (more than 6 months). Loss of HBsAg with development of anti-HBs antibody indicates recovery and immunity.

First-line treatments are oral nucleos(t)ide analogues — tenofovir alafenamide, tenofovir disoproxil fumarate, and entecavir — taken once daily for years to lifelong. They suppress HBV DNA in over 95% of patients and reduce risk of cirrhosis and liver cancer. Pegylated interferon alpha is an alternative finite-course option in selected patients.

Most patients on oral antivirals continue therapy indefinitely. Stopping treatment can cause severe flares and rapid progression to liver failure. Pegylated interferon is given as a 48-week course. Treatment may be reassessed in patients who achieve HBsAg loss or who are at very low risk of progression.

Yes. Tenofovir disoproxil fumarate is given to HBsAg-positive pregnant women with HBV DNA above 200,000 IU/mL from week 28 of pregnancy to reduce mother-to-child transmission. This, combined with hepatitis B immune globulin and birth-dose vaccine, reduces transmission to under 1%.

Hepatitis B is caused by a DNA virus, transmitted predominantly perinatally or sexually, prevented by vaccine, and managed with lifelong antivirals. Hepatitis C is caused by an RNA virus, transmitted predominantly by blood (injection drug use, contaminated transfusion), with no vaccine, but curable in 95% with 8-12 weeks of direct-acting antivirals.

Yes. Hepatitis B causes 50-55% of hepatocellular carcinoma worldwide. Annual HCC risk in cirrhotic HBV patients is 2-5%. Even non-cirrhotic HBV carriers have elevated risk, particularly with Asian or African origin, age over 40, family history of HCC, or high viral load. Surveillance with ultrasound and AFP every 6 months is standard for high-risk patients.

Yes. HBV reactivation during chemotherapy, rituximab, transplantation, biologic therapy, or HIV treatment changes can cause severe hepatitis and death. All candidates for immunosuppression should be screened for HBsAg, anti-HBc, and HBV DNA, and prophylactic antiviral therapy given where indicated.

Yes. Household and sexual contacts of HBsAg-positive patients should be tested for HBsAg, anti-HBs, and anti-HBc. Susceptible contacts should be vaccinated. Newborns of HBsAg-positive mothers must receive birth-dose vaccine and hepatitis B immune globulin within 12 hours of delivery.

WHO and CDC recommend at least one-time hepatitis B screening for all adults aged 18 and older, regardless of risk factors. The screening panel includes HBsAg, anti-HBs, and anti-HBc total. People with positive HBsAg or anti-HBc need further evaluation by a hepatologist.

People with active HBV infection (HBsAg positive) cannot donate blood. Organ donation is possible in selected circumstances with full disclosure and recipient consent. People with resolved HBV (anti-HBc positive, HBsAg negative) may be eligible to donate blood in some jurisdictions after thorough screening.

Hepatitis D virus (HDV) is a defective RNA virus that requires HBsAg for replication. HBV/HDV coinfection accelerates liver disease in 15-20 million chronic HBV patients globally. Bulevirtide became the first specific HDV therapy approved in Europe in 2020. All chronic HBV patients should be tested for HDV at least once.

Chronic HBV with effective antiviral suppression and good adherence has near-normal life expectancy. Untreated chronic HBV with progression to cirrhosis or HCC carries significantly reduced life expectancy. Early diagnosis, sustained treatment, and HCC surveillance dramatically improve outcomes.

Breastfeeding by HBsAg-positive mothers is considered safe when the infant has received birth-dose vaccine and HBIG. The infant's protection comes from vaccination, not from avoiding breast milk. Mothers with cracked nipples should temporarily express and discard milk while healing.

Avoid alcohol entirely, maintain healthy weight, eat a Mediterranean-style diet, take prescribed antivirals at the same time daily, attend regular follow-up, get vaccinated against hepatitis A, and ensure household and sexual contacts are vaccinated. Avoid raw shellfish and aflatoxin-contaminated foods.

WHO has set 2030 elimination targets — 90% reduction in new chronic infections and 65% reduction in mortality. Reaching these targets requires universal birth-dose vaccination, scale-up of testing and treatment, prevention of mother-to-child transmission, and access to affordable generic antivirals. Progress is significant but uneven globally.