Hepatitis B

Transmission (100 fold more infectious than HIV)
1. Percutaneous (needlestick) exposure
  1. Sharing non-sterile needles
  2. Tattooing
  3. Health care accidents
2. Blood Product exposure
3. Sexual contact
4. Perinatal exposure
Worldwide
1. Endemic in sub-Saharan Africa, China, Southeast Asia
  1. Acquired in early life in endemic areas
  2. Chronic Hepatitis B Prevalence: 5 to 20%
2. Worldwide Prevalence: 300 million infected
U.S.
1. Acute Hepatitis B Incidence: 21,900 per year (1.1 per 100,000) in 2015
2. Chronic Hepatitis B Prevalence: Up to 2.4 million (in 2022)
3. As of 2018, 36% of cases were injection drug related (driven by Opioid epidemic)

Hepadnavirus (DNA Virus, 42 nm in size)
1. Family: Hepadnaviridae
2. Partially double-stranded DNA
3. Has 10 Genotypes (A-J) and 30 subtypes
Components
1. Dane particle (entire virus)
2. Antigens
  1. HBsAg: Outer surface coat encases virus
  2. HBcAg: Inner nucleocapsid core encases genome
  3. HBeAg: Circulating peptide encoded by core gene
3. Genome
  1. Covalently closed circular dsDNA (cccDNA)
    1. Allows for HBV to persist in the hepatocyte nucleus despite Antiviral therapy
  2. DNA Polymerase (reverse transcriptase)
    1. Required for virus replication
Hardy infectious agent
1. Stable after 15 years storage at -20 C
2. Stable on dried glass at room Temperature for 4 weeks
3. Stable for 4 hours at 60 C
4. Stable after exposure to antiseptics
  1. Ultraviolet Radiation
  2. Benzalkonium chloride
  3. Alcohol
5. Inactivated by a few agents
  1. Glutaraldehyde
  2. Formalin
  3. Urea
Hepatitis B Virus present in blood and body secretions
1. Saliva
2. Tears
3. Vaginal secretions
4. Breast Milk
Timing
1. Incubation: 60 to 90 days on average

See Viral Hepatitis
Incidence of symptoms (subclinical in most cases)
1. Age <5 years: <10%
2. Age >5 years: 30-50%
Symptoms
1. Initial Acute Hepatitis B infection
  1. Nausea
  2. Vomiting
  3. Anorexia
  4. Fatigue (may persist)
  5. Headache
  6. Malaise
  7. Low grade fever
  8. Diarrhea
  9. Right Upper Quadrant Abdominal Pain
  10. Myalgia or Arthralgias
  11. Urticaria may also occur
2. Later Acute Hepatitis B infection
  1. Jaundice

Symptomatic management
Antiviral therapy offers no benefit in the acute phase
1. Mantzoukis (2017) Cochrane Database Syst Rev (3): CD011645 [PubMed]
Hepatitis B spontaneously resolves in 90% of adults within 3-6 months
1. Recheck HBsAg at 6 months

Outcome in adults and children over age 5 years
1. Recovery: 90%
2. Chronic Active Hepatitis: 10%
3. Fulminant Hepatitis: <1% (high mortality)
4. Premature death (Hepatocellular Carcinoma, Cirrhosis) from Chronic Hepatitis B in 25% children, 15% adults
Outcome in children under age 5 years
1. Chronic infection: 30-90%
2. Younger ages are associated with the highest risk of Chronic Hepatitis B
  1. Trepo (2014) Lancet 384(9959):2053-63 [PubMed]
Worse prognosis if Hepatitis D also present
1. Cirrhosis higher risk
2. Hepatocellular Carcinoma higher risk

Hepatitis B Vaccine
1. Only 30% of U.S. adults Hepatitis B vaccinated, despite Primary Series and indicated in all adults up to 59 years
Perinatal Exposure
1. See Hepatitis B Postexposure Prophylaxis in Newborns
Bloodborne Pathogen Exposure
1. See Hepatitis B Postexposure Prophylaxis
Reactivation of Hepatitis B
1. More common now with broadening use of tnf agents (e.g. Rheumatoid Arthritis, Crohn's Disease)
2. Screen for Hepatitis B (HBsAg, HBcAb) before starting tnf agents or Chemotherapy