Infection 12 - Viral Hepatitis Flashcards
What is hepatitis?
Where does hepatitis virus replicate?
- Hepatitis = Inflammation of the liver
- Within hepatocytes (hepatotropic), causing destruction of hepatocytes
What are the structures of the Hep B + Hep C viruses?
Hep B = double stranded DNA, enveloped virus
Hep C = single stranded (+) RNA, enveloped icosahedral virus
What liver function tests are done to check for presence of viral hepatitis?
Explain the results
1) Bilirubin (high) - liver is inflamed due to presence of viral hepatitis, and cannot conjugate bilirubin for excretion. This leads to intrahepatic jaundice.
2) Alanine transaminase/ALT (high)
+ Aspartate aminotransferase/AST (high) - high levels of these enzymes suggest hepatocyte damage.
3) Alkaline phosphates (ALP) (normal) - high levels suggest biliary tract damage, but should be relatively normal.
What is the diagnosis on the basis of the following blood test results?
- ALT = high
- Bilirubin = high
- ALP = normal
- Intra-hepatic jaundice secondary to viral hepatitis
How is hepatitis B transmitted?
1) Vertical transmission/perinatal (75% cases)
2) Sexual contact
3) I.V drug use/needle-stick injuries
4) Close household contacts
What are the symptoms of acute hep B infection?
How many individuals are able to clear the initial infection?
- Jaundice (scleral), fatigue, abdominal pain, anorexia/nausea/vomiting, arthralgia (upto 50% asymptomatic)
- Incubation period = 6 weeks to 6 months
- 80-90% clear acute infection within 6 months, roughly 10% go onto develop chronic infection
What is the course of hep B serology for someone naturally clearing the infection? (6)
1) HBsAg (surface antigen) - within 6 weeks
2) HBeAg (e-antigen) - follows shortly after
3) IgM (core antibody) - first antibody to appear
4) e-antibody - next up
5) HBsAb (surface antibody) - last antibody to appear, corresponds with viral clearance + recovery
6) IgG - IgM disappears, IgG persists for life.
What is the definition of a chronic Hep B infection?
What can chronic infection lead to?
- Persistance of HBsAg (surface antigen) after 6 months
- 25% get cirrhosis, 5% develop HCC
What is the treatment management for Hep B?
Who is the vaccine given to?
- No cure, give life-long anti-virals (some dont require at all - e.g.: inactive carriers) to suppress viral load
- Genetically engineered surface antigen, 3 doses + booster, producing surface antibody, given to babies first at 8 weeks.
What antigens/antibodies should you see in a person with:
1) Acute Hep B infection
2) Cleared Hep B infection
3) Chronic hep B infection
4) Vaccinated person
1) HbsAg + IgM +/- HbsAb
2) IgG + HbsAb
3) HbsAg + IgG
4) HbsAb
How is Hep C transmitted?
How many individuals become chronically infected?
1) IV drug users (90% of cases)
2) Sexual contact
3) Vertical transmission
4) Needle stick injuries
- 80% become chronically infection, resulting in liver disease, HCC + death
What are the symptoms of Hep C infection?
- 80% are asymptomatic
- 20% have vague symptoms (fatigue, anorexia, nausea, abdominal pain)
What blood tests are done to diagnose Hep C infection?
- Serology = Anti-Hep C antibody only
- Viral PCR = positive, confirms chronic infection
How is Hep C treated?
- Directly acting antiviral drug combo for 8-12 weeks with over 90% chance of cure but £10-60k per course and can get re-infected. No vaccine present.
Risk of transmission for needle-stick injury Hep C = 1/30, Hep B = 1/3 + HIV 1/300, what is the protocol for needle stick injury?
- Bleed and wash wound
- Collect blood + assess risk
- Start post-exposure prophylaxis (PEP) whilst monitoring serological tests
