M/I: Infectious causes of hepatitis 1 and 2 Flashcards
LO: understand the kinds of liver disease (acute and chronic) caused by viruses and the range of viruses that cause hepatitis
What are the different broad types of viral hepatitis?
Acute disease (wks to months, no chronic sequelae):
-non specific, flu-like symptoms
-jaundice, dark urine, pale faeces.
Chronic disease (years to lifetime)
-general malaise
-cirrholsis, liver cancer
Fulminant disease: Acute, precipitous infection
LO: understand that five different viruses that cause hepatitis (HAV, HEV, HBV, HDV and HCV as their predominant presentation and their different epidemiology and sequelae.
How are the 5 viruses transmitted and prevented?
Hep A: faeces, faeco-oral. Pre/post exposure vaccination
Hep B: blood/blood-dervived body fluids, percutaneous/permucosal. Pre/post exp vac.
Hep C: B/BD BF, PC/PM. Blood donor screening, risk modification behavior.
Hep D: B/BD BF, PC/PM. Pre/post exp vac, risk behav mod
Hep E: faeces, faeco-oral route. Ensure safe drinking water.
• understand the characteristics of HAV and HEV
m
• understand the epidemiology of HAV and HEV
b
• understand the features of their immune based pathogenesis
bb
• understand the laboratory diagnosis of HAV and HEV
b
• understand the current status of drugs and vaccines for HAV and HEV
b
What are the signs/sequelae of viral hepatitis and what causes them?
It is the IMMUNE response (lymphocyte infiltration- pic) to viruses that causes the damage.
Jaundice (from hyperbilirubinemia)
Cirrhosis from chronic liver damage (pic- blistering of surface, loss of lobule architecture)
Hepatocellular carcinoma.
Describe the pathogenesis of viral hepatitis
Hepatitis viruses are NOT cytolytic (replicate in but don’t lyse cells), thus most disease is immune mediated, thus you have AGE related outcomes.
Exposure early in life (less competent immune system) results in
-less severe acute disease
-higher rates of chronic infection
What are the types of hepatitis viruses and is there cross protection between them?
Hep A (infectious hepatitis) Hep B (serum hepatitis) Hep C (serum non-A, non-B) Hep D (dependent on HBV) Hep E (enteric non-A, non-B) NO they are from different families.
Hep A and E cause acute disease
Hep B and C cause chronic disease so are the most significant (but Hep D also chronic..so..?)
World distribution of Hep A?
High prevalence in low socio-economic countries e.g. Africa, Asia, South America
What is the prevalence distribution of Hep A in Australia?
Now about equal in males/females (used to be higher in males).
Much higher incidence in Indigenous ppl
What is the structure and classification of Hep AV?
Picornaviridae (small rna virus) family- Hepatovirus
Non enveloped + ssRNA virus, survive in water/stomach acid due to protein coat
Single serotype worldwide
What is the life cycle of Hep AV?
Contaminated food/water is ingested
There is REPLICATION of virus in intestinal epithelial cells
Then viraemia (spread to blood)
Reaches liver, REPLICATION (get v high levels)
Exits in bile/faeces.
