L17 - Viral hepatitis Flashcards
Briefly describe the hepatitis viruses?
Hep A, B, C, D & E
Hepatotrophic viruses
Can cause:
- fever
- jaundice
- joint pain
Give examples of viruses which may cause acute hepatitis as part of their clinical spectrum?
- Epstein-Barr virus
- Cytomegalo virus
- Herpes simplex
Hepatitis E
- structure
- transmission
- treatment
Structure
- small RNA virus
Transmission
- Faecal-oral route
Treatment
- supportive
- no proven effective drugs
What happens to the Hep E virus when it enters body?
- Crosses across wall of alimentary canal
- Transported to liver
- Liver damage occurs via T-Cell mediated immune responses
- Viral replication in liver cells
- Virus released into bile in vesciles
Incubation period of Hepatitis E
10-50 days
average: 28 days
Patients infected with Hepatitis E will usually present with…
Some patients will also have the following symptoms:
Jaundice
Fever, malaise, nausea, vomiting, upper abdominal pain
Hepatitis B
- transmission
- incubation period
- at risk?
Hep B Parenteral, sexual, perinatal (40-160 days), avg. 90 days Risk: - injecting drug users - infants of carrier - multiple sexual partners
Hepatitis C
- transmission
- incubation period
- at risk?
Hep C Parenteral, sexual, perinatal (15 - 160 days) avg. 60 days Risk: - recepient of unscreened blood products - injecting drug users
Hep D
- transmission
- incubation period
- at risk?
Hep D - parenteral - (20 - 50 days) Risk: - injecting drug users
Hep E
- transmission
- incubation period
- at risk?
Hep E - feacal oral - 40 days Risk: - travellers to endemic areas
Describe investigations of IgA in diagnosing hep A
- anti HAV antibodies usually present at onset of symptoms (decline over 3-6 months)
Presence of anti HAV IgG antibodies will reflect:
- immunity from previous exposure (or immunisation)
Liver function test results in presence of Hep A
- raised alanine
- raised asparate aminotransferase
- rise in bilirubin
Management of hep A
- supportive
Prevention
- good sanitation
- personal hygiene
- active immunisation with dead virus
Is the acute infection of hepatitis B, symptomatic or asymptomatic?
usually asymptomatic
How might you determine presence of chronic hepatits B?
- presence of HBV surface antigen (HBVsAg) in blood for more than 6 months
Hepatitis B
- structure
- forms
DNA virus
Can occur in three forms
1. Dane particle
2. & 3. Variants of HBVsAg
Describe structure of Dane particle
Complete virus
HBV DNA polymerase in outer coat.
Describe the structure of HBV core antigen?
HBVcAg
- formed of core protein containing incompletely double stranded circular DNA and DNA polymerase
Clinical features of hepatitis B
- acute infection present as mild illness then followed by jaundice.
Some patients:
- fever, malaise, anorexia, nausea, vomiting, upper abdominal pain.
Characteristics of acute infection of hepatitis A
- Liver function tests
- raised serum AST
- raised serum ALT
- rise in bilirubin - HBVsAg: +
- HBVeAg: +
- indicates high degree of infectivity
- HBVsAg cleaves to form HBVeAg
Hep B infection will be assessed by its serology for what
- surface antigen
- early antigen
Why must Hep B also be present if Hep D is present?
- Hep D virus borrows its outer coat from hep B.
- requires coat of HBVsAg for its replication and survival
If acute infection of hep b resolves what will occur?
- HBVeAg disappears within few months
- disappearance HBVsAg
- normalisatoin of aminotransferases
After resolution of acute infection of hep B
- IgM antibodies to HBVcAg are lost
- total antibodies to HBVcAb remain positive lifelong
- most develop lifelong antibodies to HBVsAg
Transmission of HBV
- Blood borne virus
- contaminated blood, needle stick
Clinical signs of HBV
Acute hepatitis
- flu like symptoms
- right upper quadrant discomfort
- jaundice
In diagnosis of HBV what do the following markers indicate:
- HBsAg
- Anti- HBs
- Anti- HBc
- HBeAg
- HBeAg
- HBsAg
- antigen indicating infection - Anti- HBs
- indicates immunity - Anti- HBc
- previous or ongoing infection - HBeAg
- high infectivity - HBeAg
- low infectivity
Management of Hep B
Usually supportive.
However injection of pegylated interferon may be given (1 year only)
Prevention of Hep B
- active immunisation with vaccine containing HBVsAg
- HBV-specific immunoglobulin
- short term, immediate, passive protection
Describe Hep D virus
Rna core, requires coat of HBVsAg for its replication and survival
Treatment for HDV
- no drug therapy effective
- liver transplantation may be required
- PEG interferon for 48 weeks mainstay of treatment
Describe hep C
- RNA virus
- blood borne transmission
- vertical transmission
- can be asymptomatic
What occurs once hep C virus enters cell?
- virus infects hepatocytes, producing virons
- asymptomatic phase
- immune response results in viral clearance
HCV diagnosis
- detection of hep C antibodies suggests infection at some time.
- small rise in aminotransferases
- presence of antibodies IgG to HCV
Chronic infection of HCV suggested by
HCV RNA (viral load)
After infection how long might it take for IgG antibodies to HCV to appear?
6-12 weeks approx for IgG antibodies to HCV to appear.
During that time only test for HCV RNA may be positive
HCV RNA testing
Indicates viraemia
Ongoing viral replication
After liver transplantation what is recommended to prevent HBV recurrence
- combination of hepatitis B immunoglobullin HBIG and a NA
