Viral Hepatitis B and D Flashcards
Define
DEFINITION: hepatitis caused by infection with hepatitis B virus (HBV), which may follow an acute or chronic course
- Chronic is defined as viraemia and hepatic inflammation continuing for > 6 months
Hepatitis D virus (HDV) is a defective virus, that may only co-infect with HBV or superinfect people who are already carriers of HBV
Cause
HBV is an enveloped, partially double-stranded DNA virus
Transmission: sexual contact, blood and vertical transmission (from mother to baby)
Various viral proteins are produced such as:
- Core antigen (HBcAg)
- Surface antigen (HBsAg)
- e antigen (HBeAg) (high infectivity)
HDV is a single-stranded RNA virus coated with HBsAg
Antibody and cell-mediated immune response to viral replication leads to liver inflammation and hepatocyte necrosis
Histology can show mild to severe inflammation and changes to cirrhosis
Risk Factors
- IV drug use
- Unscreened blood and blood products
- Infants of HBeAg-positive mothers
- Sexual contact with HBV carriers
- Younger individuals (particularly babies) are more likely to become chronic carriers
- Genetic factors are associated with varying rates of viral clearance
Epidemiology
- Common
- 1-2 million deaths annually
- Common in Southeast Asia, Africa and Mediterranean countries
- HDV is also found worldwide
Symptoms
Incubation period: 3-6 months
1-2 week prodrome consisting of:
- Malaise
- Headache
- Anorexia
- Nausea and vomiting
- Diarrhoea
- RUQ pain
- Serum-sickness type illness (e.g. fever, arthralgia, polyarthritis, urticaria, maculopapular rash)
Jaundice develops with dark urine
Recovery: 4-8 weeks
1% develop fulminant liver failure
Chronic carriage may be diagnosed after routine LFT testing or if cirrhosis or decompensation develops
Signs
Acute
- Jaundice
- Pyrexia
- Tender hepatomegaly
- Splenomegaly
- Cervical lymphadneopathy (in 10-20% of patients)
- Occasionally: urticaria and maculopapular rash
Chronic
- May be no findings
- May have signs of chronic liver disease or decompensation
Investigations
Viral Serology
- Acute HBV: HBsAg positive, IgM anti-HBcAg
- Chronic HBV: HBsAg positive, IgG anti-HBcAg, HBeAg positive or negative
HBV Cleared or Vaccinated against HBV:
- Anti-HBsAg antibody positive
- IgG anti-HBcAg
HDV infection:
- Detected by IgM or IgG against HDV
- PCR is used for detection of HDV
LFTs
- High: AST, ALT, ALP, bilirubin
Clotting
- High PT (in severe disease)
Liver Biopsy
Management
Prevention: blood screening, safe sex, instrument sterilisation
Passive immunisation
- Hepatitis B immunoglobulin following acute exposure and to neonates born to HBeAg-positive mothers (in addition to active immunisation)
Active immunisation
- Recombinant HBsAg vaccine for individuals at risk and neonates born to HB
Acute HBV Hepatitis
- Symptomatic treatment (antipyretics, antiemetics and cholestyramine) and bed rest
- Notifiable disease
Chronic HBV
- Interferon alpha (standard or pegylated)
- Side-effects: flu-like symptoms such as fever, chills, myalgia, headaches, bone marrow suppression and depression
- Nucleoside/nucleotide analogues (adefovir, entecavir, telbivudine, tenofovir)
Complications
- 1% get fulminant hepatic failure
- Chronic HBV infection (10% of adults, much higher in neonates)
- Cirrhosis
- HCC
- Extrahepatic immune complex disorders (e.g. glomerulonephritis, polyarteritis nodosa)
- Superinfection with HDV may lead to acute liver failure or more rapidly progressive disease
Prognosis
Adults: 10% of infections become chronic
Of the chronic infections, 20-30% will develop cirrhosis
