7 Hepatitis B Flashcards
what genome does hep A have
RNA
what is the RNA like in hep A
+ve single stranded RNA
how is hep A transmitted
faecal-oral route of transmission
- Entry via contaminated food or water
- Excreted in faeces
what are the viral and serological markers of infection
ALT increases - acute hep
Virus replicate in small bowel into blood stream to liver and release in faeces
When reach liver = ill but before not detected in blood = blood donor = transmit hep
IgM AB disappear
IgG response slower but then persists
Hepatitis A Virus – Consequences of Infection
- Asymptomatic infection
- Acute icteric hepatitis
- Fulminant hepatitis (rare)
Prevention of hepatitis A
Care with food and water
Vaccination
> Whole killed virus
what is hep B genome
Unusual genome – partially ds = family is called Hepadnavirus
compact– encodes few proteins
what forms around DNA in hep B
Core forms capsid around DNA
what are the 6 diagnostic markers for hep B
HBsAg; HBcAg; HBeAg
Anti-HBs; Anti-HBc; Anti-HBe
HBV replication
- Enters cell as partially ds DNA
- 2nd strand is completed covalently closed circular DNA (cccDNA)
- Synthesis and packaging of pregenomic RNA
- Reverse transcription of pregenomic RNA within capsid partially dsDNA
Natural History of HBV Infection – Adults and neonates
acute infection:
- subclinical infection
- acute iceteric hep
- fulminant hep (1%)
- chronic infection (5-10%) = healthy or chronic hep or cirrhosis ca liver
what is Cirrhosis ca liver
normal liver architecture replaced by fibrous (increased risk in hep b – transforming virus)
what is a chronic
virus continually replicating
what causes most chronic HBV in UK
imported
Hepatitis B: Modes of Transmission
- Perinatal (mother to baby at birth)
- Sexual
- Parenteral (exposure to someones blood - unsafe injections and transfusion)
Acute hepatitis B detection
HBsAg positive – doesn’t say when got infected
IgM anti-HBc positive - IgM AB as marker of recent infection – as come and go
Acute infection will either resolve or become chronic
Resolved acute HBV infection
If resolved = Would have lost surface antigen = surface antigen negative HBsAg disappears (may take up to 6 months)
what is a marker of past infection
anti-HBc (IgG)
what may arise from result of vaccination
anti-HBs
Chronic HBV infection
Defined as persistence of HBsAg for > 6 months
Chronic HBV infection - HBeAg positive
- high infectivity eg needlestick
- increased risk of inflammatory liver disease
Chronic HBV infection - Anti-HBe positive
- low infectivity
- low risk of CLD
Prevention of HBV infection
- Simple precautions
- Hepatitis B immunoglobulin (passive immunisation)
- Hepatitis B vaccine (active immunisation)
- Recombinant HBsAg – induces anti-HBs
what are the risk groups that should be vaccinated
- Healthcare workers
- Baby for infected mother
- Sexual partners
what must healthcare workers that perform EPP be tested for
- Be tested for HBsAg
- If HBsAg +ve, check for HBeAg
- If HBeAg +ve, BANNED from EPPs
