Hepatitis B

About Hepatitis B

Hepatitis B is caused by the hepatitis B virus HBV, discovered by Baruch Blumberg in 1965 Nobel Prize 1976. WHO estimated that about 254 million people were living with chronic HBV infection in 2022, and HBV related cirrhosis and liver cancer cause a large number of deaths each year. HBV is transmitted through blood, sexual contact, and from mother to child during birth vertical transmission, which is the primary route in endemic areas East Asia, sub Saharan Africa. Adults who acquire HBV have approximately 95 percent chance of clearing the virus, while vertical transmission results in approximately 90 percent chronic infection, as the immature immune system tolerates the virus. Chronic HBV may be asymptomatic for decades. Active hepatitis causes fatigue, nausea, abdominal pain, jaundice, and dark urine. Complications include cirrhosis and hepatocellular carcinoma HCC, which can occur even without cirrhosis in HBV. Diagnosis involves HBsAg, anti HBs, anti HBc panel. HBsAg positive for over 6 months indicates chronic infection. HBV DNA viral load guides treatment decisions. Treatment suppresses but does not cure HBV. First line antivirals entecavir, tenofovir disoproxil TDF, tenofovir alafenamide TAF are safe for long term use with high barriers to resistance. Pegylated interferon is an alternative for selected patients. Regular surveillance for liver cancer, usually with ultrasound, is recommended for people with chronic HBV at higher risk, such as those with cirrhosis. The HBV vaccine, the first anticancer vaccine, was developed from plasma in 1981 and recombinant DNA technology in 1986. A complete vaccine series protects the large majority of recipients. WHO recommends a birth dose of vaccine soon after delivery, which greatly reduces mother to child transmission.