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- Y6 Gastrointestinal > Viral Hepatitis (B and D) > Flashcards

Viral Hepatitis (B and D) Flashcards

1
Q

Define hepatitis B and D.

A

Hepatitis caused by infection with hep B virus (HBV) which may follow an acute or chronic (defined as viraemia and hepatic inflammation continuing >6 months) course.

Hep D virus (HDV), a defective virus, may only co-infect with HBV or superinfect persons who are already carriers of HBV.

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2
Q

Which virus is related to hep B?

A

Hepatitis D – you can only get D if you have B. two Ds make a B

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3
Q

Can you be infected with only HDV?

A

Hep D virus (HDV), a defective virus, may only co-infect with HBV or superinfect persons who are already carriers of HBV.

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4
Q

What type of virus is HBV? How is it transmitted?

A

HBV is enveloped, partially double stranded DNA virus

Transmission by sexual contact, blood and vertical transmission

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5
Q

Name 3 viral proteins produced by HBV. How can you tell if someone is particularly infectious?

A

Various viral proteins are produced including:

  1. core antigen (HBcAg),
  2. surface antigen (HBsAg) and
  3. e antigen (HBeAg).

HBeAg is a marker of high infectivity.

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6
Q

What type of virus is HDV? Which proteins does it produce?

A

HDV is a single-stranded RNA virus

It is coated in HBsAg (surface antigen)

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7
Q

Summarise the pathophysiology of hepatitis.

A

Antibody and cell mediated immune responses to viral replication lead to liver inflammation and hepatocyte necrosis

Histology can be variable from mild to severe inflammation and changes of cirrhosis.

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8
Q

What are the risk factors for HBV?

A
  • IV drug use
  • unscreened blood and blood products
  • infants of HbeAg-positive mothers
  • sexual contact with carriers
  • genetic - factors associated with increased rates of viral clearance
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9
Q

What affects the risk of persistant HBV infection?

A

Varies with age

Babies are more likely to develop chronic carriage

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10
Q

How common are HBV/HDV?

A
  • Common but HBV is relatively uncommon in UK
  • 350 million worldwide infected with HBV
  • Common in southeast Asia, Africa, Mediterranean
  • HDV also found worldwide
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11
Q

What is the incubation period for HBV?

A

3-6 months with a 1-2 week prodrome of malaise, headache, anorexia, nausea, vomiting, diarrhoea, RUQ pain

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12
Q

How does HBV present?

A

May present at any stage:

  • 1-2 week prodrome of malaise, headache, anorexia, nausea, vomiting, diarrhoea, RUQ pain
  • May experience serum sickness type illness - e.g. fever, arthralgia, polyarthritis, urticaria, maculopapular rash
  • Jaundice then dark urine and pale stools
  • Recovery within 4-8 weeks
  • 1% develop fulminant liver failure
  • Chronic carriage may be diagnosed after routine LFT or if cirrhosis decompensates
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13
Q

What percentage of those infected with HBV develop fulminant liver failure?

A

1%

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14
Q

What are the signs of HBV/HDV on examination?

A

Acute -

  • jaundice
  • pyrexia
  • tender hepatomegaly
  • splenomegaly
  • cervial lymphadenopathy in 10-20%
  • urticaria/maculopapular rash occasionally

Chronic:

  • no findings or
  • signs of chronic liver disease
  • decompensation
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15
Q

What investigations would you do for HBV/HDV?

A

Viral serology:

  • Acute HBV - HbsAg +ve, IgM anti-HbcAg (core antigen)
  • Chronic HBV - HbsAg +ve, IgG anti-HBcAg, HbeAg +ve or -ve (negative in precore mutant variant)
  • Cleared HBV/immunity - anti-HBsAg +ve, IgG anti-HBcAg
  • HDV infection - detected by IgM or IgG against HDV

Other:

  • PCR - detects HBV DNA and is the most sensitive measure of ongoing viral replication
  • LFT - ++ AST and ALT, high bilirubin, high AlkPhos
  • Clotting - high PT in severe disease
  • Liver biopsy - percutaneous or transjugular if clotting is deranged or ascites present
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16
Q

What type of immunisation is available for HBV?

A

Passive immunisation - Hep B immunoglobulin (HBIG) following acute exposure and to neonates born to HbeAg +ve parents (in addition to active immunisation)

Active immunisation - recombinant HbsAg vaccine for individuals at risk and neonates born to HBV +ve mothers.

Immunisation against HBV protects from HDV

17
Q

How do you manage chronic HBV?

A

Chronic HBV Treatment

SC treatment 48 weeks duration:

  • Interferon Alpha - used in a subset of patients who look like they are clearing the virus by themselves. Do not use in patients who may require a liver transplant.

Long term treatments (PO):

  • Lamivudine
  • Tenofovir
  • Entecavir
  • Emtricitabine

Liver Transplantation – requires various other treatments (e.g. immunosuppression, nucleoside analogues, hepatitis B Ig)

Liver Failure

  • Antivirals are very effective in treating the viral hepatitis - usually takes ~9 months in liver failure
18
Q

What are the complications of HBV/HDV?

A
  • Fulminant liver failure in 1%
  • Chronic HBV infection (~10% adults but higher in neonates) - i.e. persistence of HbsAg for 6 months or more
  • Cirrhosis
  • Hepatocellular carcinoma (AFP rises)
  • Extrahepatic immune complex disorders e.g. glomerulonephritis, polyarteretis nodosa
  • Superinfection with HDV may lead to acute liver failure or more rapdly progressive disease
19
Q

What is the prognosis with HBV?

A

10% infections become chronic and of these 20-30% develop cirrhosis

Better prognosis with:

interferon therapy if high serum transaminases,

low HBV DNA,

active histological changes

absence of complicating disease

20
Q

Should HBV prophylaxis be given in these cases?

  • Vaccinated
  • Partially vaccinated
  • Fully vaccinated with primary course
  • Known non-responder to HBV vaccines
A
21
Q

What % of HBV infected adults go on to develop chronic Hep B?

A

10%

22
Q

Define chronic Hepatitis B:

A

Persistence of HBsAg for 6 months or more after acute HBV infection

23
Q

How do HBV DNA levels correspond to prognosis?

A

Low levels correspond with lower:

  • incidence of cirrhosis
  • incidence of HCC

Therefore high levels are an indication of need to treat.

24
Q

Who gets the HBV vaccine?

A

Pre-exposure prophylaxis

  • Routine childhood immunisation in the UK since 2017
  • High risk population

Post-exposure prophylaxis

  • Neonate born to mother living with hepatitis B
  • Sexual partner: HBV vaccine +/- HBIG (within one week from the contact)
  • Needle stick injury
25
Q

Describe the virology of HDV.

A

Single-stranded, defective, circular RNA genome virus that relies on HBV for replication

Smallest virus known to infect man

Incubation 3-6 weeks

Blood-borne transmission

26
Q

What are the two patterns of infection with HBV-HDV and which is worse?

A
  1. HBV-HDV coinfection
  • Getting both B and D at the same time
    • Similar to classic acute HBV - causes elevated ALT and IgM anti-HDV at the same time as symptoms; mostly self limited
  • Gives acute HBV (<5% progress to chronic)
  1. HBV-HDV superinfectioin
  • When you already have B and you get D.
  • 80% risk of chronic infection
  • Increased risk of cirrhosis and HCC than chronic hep B alone
27
Q

What is the management of HDV?

A

Treatment: PEG-interferon alpha is licensed for HDV superinfection in CHB

Prevention: pre-exposure HBV immunisation

- Y6 Gastrointestinal (70 decks)

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