Viral Hepatitis Flashcards
1
Q
Hepatitis - causes
A
- viral (A-E)
- alcohol-related liver disease
- autoimmune hepatitis
- hereditary (wilson’s, haemochromatosis)
- NAFLD
2
Q
Viral hepatitis - general pathophys
A
- viral proteins presented by MHC I on hepatocytes
- cytotoxic reaction by CD8+ T cells
- apoptotic councilman bodies on histology
- high transaminases (ALT > AST) in viral hepatitis
(unlike alcoholic hepatitis where AST > ALT) - atypical lymphocytes
- high bilirubin (both c.b. and u.c.b.) and urobilinogen
- infection >6 months = chronic hepatitis
3
Q
Viruses - general features
A
- A + E = ACUTE only; rest can be acute or chronic
- chronic = approx 90% Hep C and 10% Hep B
- Hep B is a double-stranded DNA virus; rest are single-stranded RNA
- B, C, D are enveloped (lipid outer layer), A + E are “naked”
- fulminant hepatitis = can occer in Hep A, B, C, E
4
Q
Clinical presentation (general)
A
- often asymptomatic If symptomatic: - anorexia, N+V - Jaudice +/- dark urine, pale stools - malaise - fever - RUQ pain - hepatomegaly +/- ascites
5
Q
Hepatitis B - general features
A
- transmission: percutaneous and permucosal routes. E.g. IVDU, needle sticks, vertical (mother to baby) and sexual transmission
- common in endemic regions - Asian or African
- most cases are acute
- only 20% are chronic (more risk the younger you are)
- linked to liver cancer
- sometimes a/w arthritis and erythema nodosum
6
Q
Hepatitis B - antigens (bad guys)
https://www.youtube.com/watch?v=6yKIpQElh-4
A
- Surface antigen (HBsAg) = most relevant one; part of envelope; signifies active infection (either early acute or chronic infection) or recent vaccination
- Core antigen (HBcAg) = part of capsid –> undetectable in serum, so no test for it
- E antigen (HBeAg) = signifies replication of virus, so active (acute or chronic) and highly infectious. If +ve in chronic, needs treatment
7
Q
Hepatitis B - antibodies
A
- Surface antibody (Anti-HBs or HBsAb) = against surface antigen (IgM early on, then IgG); +ve if fully vaccinated or had an acute infection that resolved. Not present during an active chronic infection.
- Core antibody (Anti-HBc or HBcAb) = against core antigen (IgM early on, then IgG); found during and after the resolution of an acute infection, or during a chronic infection. Also can be found during window period
8
Q
Hep B - window period
A
- short period during acute infection or early vaccination
- abscence of surface antigen and antibody in blood (as they are bound together) - antigen 1:1 antibody ratio
- HBeAg or Anti-HBc may be present
- one could miss diagnosis as no surface Ag and Ab are present, so look out for E antigen or core antibody
9
Q
Hep B - post window period (scenarios)
VACCINATION
A
Vaccination
+ve HBsAb (means they are protected)
-ve HBsAg
-ve HBcAb (were not infected in the first place)
10
Q
Hep B - post window period (scenarios)
RESOLUTION OF ACUTE INFECTION
A
Resolution of acute infection
+ve HBsAb (antibody fought the infection)
-ve HBsAg (antigen is now depleted)
+ve HBcAb
11
Q
Hep B - post window period (scenarios)
PROGRESSION TO CHRONIC INFECTION
A
Chronic infection
+ve HBsAg (antigen still high so infected)
-ve HBsAb (antibody did not fight the infection)
+ve HBcAb
12
Q
Hepatitis C - general features
A
- transmission = percutaneous (parenteral, sexual, vertical). RFs as per Hep B + unsafe medical procedures, Hx of transfusion or transplant
- most common form of viral hepatitis (over 70 million cases worldwide)
- gold standard test is HCV RNA test with PCR: detects viral load in blood early on
- whilst patients will eventually develop anti-HCV antibodies it should be remembered that patients who spontaneously clear the virus will continue to have anti-HCV antibodies
- Ishak score used to assess severity of chronic hep C (based on biopsy)
- can progress to cirrhosis and liver cancer (risk higher in alcoholics or co-infected with HIV)
13
Q
Hepatitis A - general features
A
- transmission = fecal-oral route
- RF: living or TRAVELLING to an endemic area (eg Africa, some parts of Asia), close contact with infected person, exposure to a known food-borne outbreak, contaminated water
- acute ONLY
- HAV IgM = active infection
- HAV IgG = resolved or vaccinated
14
Q
Hepatitis E - general features
A
- transmission = fecal-oral route
- widespread in Southeast Asia, northern and central Africa, India, and Central America
- exposure to a known food-borne outbreak esp. undercooked seafood, contaminated water
- acute ONLY
- HEV IgM = active infection
- HEV IgG = resolved
- no vaccine available
- can be severe in pregnant women and lead to fulminant hepatitis (massive necrosis of liver parenchyma and acute yellow atrophy)
15
Q
Hepatitis D - general features
A
- trasmission: similar to HBV - needs HBV to infect
- acute or chronic
Two patterns of infection
1. Coinfection (at the same time as HBV)
2. Superinfection (infects later) - more severe - either IgM or IgG indicate active infection (IgG is not protective in this case)
