Hepatitis B Overview Quiz

Hepatitis B

• Clinical Manifestations:

  • Acute infection can be asymptomatic or symptomatic.
  • Likelihood of symptoms is age-dependent: infants <1 year (<1%), children 1-5 years (5-15%), adults >5 years (30-50%).
  • Symptoms vary: subacute (nonspecific - anorexia, nausea, malaise), clinical hepatitis (jaundice), fulminant hepatitis.
  • Extrahepatic manifestations: arthralgia, arthritis, rashes, thrombocytopenia, polyarteritis nodosa, glomerulonephritis (may precede jaundice).
  • Papular acrodermatitis (Gianotti-Crosti syndrome) is an extrahepatic manifestation, but rare due to universal infant immunization. More commonly associated with Epstein-Barr virus and enteroviruses.

• Chronic HBV Infection:

  • Defined as persistent presence of HBsAg, HBV DNA, or HBeAg in serum for at least 6 months, in absence of IgM anti-HBc antibody.
  • Risk of chronic infection increases with age at infection:
    • Perinatally or in first year: ~90%
    • 1-5 years: 25-50%
    • Older children and adults: 5-10%
  • Increased risk with immunosuppression or underlying chronic illness (e.g., end-stage renal disease).
  • Untreated chronic infection can lead to premature death from HBV-related hepatocellular carcinoma or cirrhosis.

• Untreated Chronic HBV Course:

  • Varies by population, reflecting differences in age of acquisition, HBeAg loss rate, and HBV genotype.
  • Most children are asymptomatic.
  • Perinatally infected children: normal or minimally elevated ALT, mild liver abnormalities, detectable HBeAg, high HBV DNA (>20 000 IU/mL) for years/decades.
  • Infection during later childhood/adolescence: more active liver disease, elevated aminotransferase levels, higher infectivity.

• Loss of HBeAg:

  • Transition common in chronically infected people.
  • Often accompanied by anti-HBe development, reduced HBV DNA/ALT, and potential temporary liver disease exacerbation.
  • Patients remain at higher risk of liver failure despite inactive chronic infection.

• Resolved Hepatitis B:

  • Clearance of HBsAg, normalized liver enzyme (ALT) levels, development of anti-HBs.
  • Clearance rate of HBsAg is 1-2% annually in adults, less than 1% in children.
  • Reactivation possible with immunosuppression, e.g., anti-TNF agents, DMARDs.

• Etiology:

  • HBV is a 42 nm enveloped DNA virus in the Hepadnaviridae family.
  • Viral particle includes: HBsAg outer lipoprotein envelope, HBcAg inner nucleocapsid.

• Epidemiology:

  • Transmission: infected blood/body fluids (blood, serum, semen, vaginal secretions, cerebrospinal, synovial, pleural, pericardial, peritoneal, amniotic fluids; human milk, saliva, tears are less so).
  • Primary reservoirs: individuals with chronic HBV infection.
  • Common transmission routes: percutaneous/permucosal exposure, sharing nonsterile needles/syringes/glucose monitoring devices, sexual contact, perinatal exposure, household exposure.
  • Child-to-child transmission risk is relatively low in areas with high Hepatitis B vaccination.
  • Transmission through bites (with HBsAg present in biter's blood) is theoretical but not widely reported.
  • Blood transfusions are rare in developed countries due to screening and inactivation measures.
  • Perinatal transmission is highly efficient (70-90% for mothers with HBsAg and HBeAg, 5-20% for HBsAg positive but HBeAg negative).

• Incubation Period: 45-160 days (average ~90 days).

• Diagnostic Tests:

  • Serologic tests detect HBsAg, HBeAg, anti-HBs, total anti-HBc, IgM anti-HBc, anti-HBe for antigens/antibodies.
  • Nucleic acid amplification testing (NAAT), PCR: quantify HBV DNA in plasma/serum.
  • Commercially available assays vary but are used to monitor chronic infection and treatment response.

• Clinical Course:

  • Acute HBV infection can resolve or progress to chronic infection.
  • Treatment for acute HBV infection is usually not required, except in cases with acute liver failure.
  • Treatment of chronic HBV infection is targeted to prevent progression to liver failure and Hepatocellular carcinoma. Therapies include nucleoside analogues.

• Treatment:

  • Uncomplicated acute infections usually do not require treatment.
  • Nucleoside/nucleotide analogs used in acute liver failure.

• Vaccination:

  • High vaccination coverage significantly lowered the incidence of HBV infection in past decades.
  • Vaccination recommendations vary by age, risk factor, and prior vaccination status.
  • HBV vaccination highly effective in preventing perinatal and other modes of transmission.

• High-Risk Groups:

  • Injection drug users
  • Individuals with multiple sexual partners
  • Men who have sex with men
  • People with surgery 6 weeks-6 months prior to symptom onset
  • Staff in institutions caring for people with developmental disabilities, hemodialysis patients
  • Sexual/household contacts of infected individuals
  • People with diabetes mellitus

• General Recommendations:

  • HBV vaccination highly effective in preventing infection in susceptible groups
  • Screening pregnant women for HBV infections important to prevent transmission to offspring
  • Immunization of previously unvaccinated adults at risk is recommended.

• Estimated International Prevalence: Varies widely by region; highest in regions of high endemicity such as Asia, Africa and Pacific Islands. Noteworthy regional differences.

• Clinical Course:

  • Acute HBV infection is usually self-limited, but can progress to chronic infection if the virus persists.
  • Chronic HBV infection can lead to serious liver disease, ultimately impacting quality of life and leading to potentially life-threatening complications including liver failure and liver cancer (hepatocellular carcinoma).

• Isolation and Control:

• Standard precautions are sufficient for patients with HBV infection, particularly in the hospital setting.

Test your knowledge on the clinical manifestations and chronic infection of Hepatitis B. This quiz covers symptoms, risk factors, and extrahepatic manifestations linked to the virus. Whether you're a student or a healthcare professional, it's a great way to assess your understanding of this important topic.