hepatitis B

hepatitis B
Name	Hepatitis B
Field	Virology, Infectious disease, Hepatology
Causes	Hepadnaviridae, DNA virus
Diagnosis	Serology, PCR
Prevention	Vaccination, Screening
Treatment	Antivirals, Supportive care

hepatitis B is an infectious liver disease caused by a DNA virus of the Hepadnaviridae family that produces acute and chronic infection, leading to inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma. The disease has global distribution and interacts with healthcare systems, public health initiatives, immunization programs, and antiviral drug development. Clinical care involves coordinated efforts among specialists in virology, hepatology, oncology, and maternal-child health.

Virology

The etiologic agent belongs to a small, enveloped DNA virus characterized by partially double-stranded relaxed circular DNA and reverse transcription during replication; key molecular features were elucidated in studies at institutions such as Centers for Disease Control and Prevention, National Institutes of Health, Rockefeller University, Cold Spring Harbor Laboratory, and Institut Pasteur. The virus encodes surface antigens, core proteins, polymerase with reverse transcriptase activity, and X protein that modulates transcription; these elements were subjects in research by groups at Harvard Medical School, Johns Hopkins University, University of Oxford, Karolinska Institute, and Max Planck Society. Viral entry involves interactions with liver-specific receptors, and research into receptor function referenced laboratories at University of Tokyo, University of California, San Francisco, Imperial College London, and Duke University Medical Center. Genotypes and subgenotypes with epidemiologic relevance were mapped through collaborations including World Health Organization, Bill & Melinda Gates Foundation, Wellcome Trust, and sequencing centers at Sanger Institute and Broad Institute.

Epidemiology

Global prevalence and incidence have been assessed in surveillance systems operated by World Health Organization, United Nations Children's Fund, European Centre for Disease Prevention and Control, Pan American Health Organization, and national agencies such as Public Health England and Centers for Disease Control and Prevention. Endemic patterns vary across regions studied by teams in China, India, Nigeria, Egypt, Russia, Brazil, Japan, and South Africa, with transmission routes including perinatal exposure evaluated in cohorts from University of Hong Kong, Seoul National University Hospital, National Taiwan University Hospital, and Karolinska University Hospital. Outbreak investigations have been reported in settings tracked by Centers for Disease Control and Prevention, Médecins Sans Frontières, Red Cross, and national ministries of health during events like mass vaccination campaigns overseen by Gavi, the Vaccine Alliance and emergency responses coordinated with World Health Organization.

Clinical presentation and complications

Acute infection presents with symptoms documented in clinical series from Mayo Clinic, Cleveland Clinic, Charité – Universitätsmedizin Berlin, St Thomas' Hospital, and Massachusetts General Hospital, including jaundice, fatigue, anorexia, abdominal pain, and elevated liver enzymes reported in case registries shared with tertiary centers like University College London Hospitals and Mount Sinai Health System. Chronic infection can progress to cirrhosis and hepatocellular carcinoma described in oncology cohorts at Memorial Sloan Kettering Cancer Center, MD Anderson Cancer Center, Tata Memorial Centre, National Cancer Center Japan, and Royal Marsden Hospital, with complications such as hepatic decompensation, portal hypertension, and extrahepatic manifestations studied by multidisciplinary teams at Johns Hopkins Hospital and UCSF Medical Center. Populations at higher risk identified in epidemiologic studies include people in cohorts from Prison Service settings, antenatal clinics linked to London School of Hygiene & Tropical Medicine, and cohorts enrolled through African Field Epidemiology Network.

Diagnosis

Laboratory diagnosis relies on serologic markers and nucleic acid testing performed by reference laboratories such as Quest Diagnostics, Laboratory Corporation of America, Public Health England's Colindale laboratory, and research centers at Institut Pasteur and Karolinska Institute. Tests include surface antigen detection, e antigen, core antibody, and quantitative viral DNA by polymerase chain reaction platforms developed by companies and academic groups in collaborations with Roche, Abbott Laboratories, Cepheid, and academic centers like Yale School of Medicine and Stanford University School of Medicine. Imaging modalities used for assessment of liver disease severity are available at tertiary centers including Cleveland Clinic, Mayo Clinic, and Addenbrooke's Hospital, while histopathology interpretation is standardized through pathology networks such as College of American Pathologists and Royal College of Pathologists.

Prevention and vaccination

Universal infant vaccination policies promoted by World Health Organization, implemented via programs supported by Gavi, the Vaccine Alliance, UNICEF, and national immunization programs in China, United States, United Kingdom, Australia, and Brazil have markedly reduced incidence in many regions. Licensed vaccines derived from recombinant surface antigen were developed by collaborations involving vaccine manufacturers and academic groups at University of Pennsylvania, Walter Reed Army Institute of Research, and private industry partners including GlaxoSmithKline and Merck & Co.. Strategies include birth-dose vaccination, maternal screening protocols used in obstetric units at Kaiser Permanente, Aga Khan University Hospital, and Singapore General Hospital, and harm-reduction programs linked to World Health Organization guidance and nonprofit organizations such as International Red Cross and Red Crescent Movement.

Treatment and management

Antiviral therapy with nucleos(t)ide analogues and interferon formulations recommended in guidelines from American Association for the Study of Liver Diseases, European Association for the Study of the Liver, Asia-Pacific Association for the Study of the Liver, and national societies such as Japanese Society of Hepatology aims to suppress viral replication and reduce progression risk; pharmaceutical development involved entities such as Gilead Sciences, GlaxoSmithKline, Roche, and academic investigators at University of California, San Diego and University of Barcelona. Management of advanced liver disease may require referral networks including transplant centers like University of Pittsburgh Medical Center, King's College Hospital, and Toronto General Hospital. Clinical trials registered through networks such as ClinicalTrials.gov and coordinated by consortia like HepNet and European Viral Hepatitis Prevention Board evaluate novel agents, immune therapies, and combination regimens.

Public health and screening programs

Screening strategies endorsed by World Health Organization, Centers for Disease Control and Prevention, European Centre for Disease Prevention and Control, and national health services in Canada, United Kingdom, United States, and Australia focus on antenatal screening, blood donor testing coordinated by American Red Cross and national blood services, and targeted programs for migrants and high-risk groups implemented by organizations such as Doctors Without Borders and International Organization for Migration. Surveillance systems integrate data from ministries of health, research consortia at London School of Hygiene & Tropical Medicine and Johns Hopkins Bloomberg School of Public Health, and funding from agencies including National Institutes of Health and Wellcome Trust to monitor progress toward elimination goals outlined by World Health Organization and regional health bodies.

Category:Infectious diseases