Viral hepatitis B and D Flashcards
definition of hepatitis B
hep caused by HBV
may follow acute or chronic (viraemia and hepatic inflammation >6mo) course
definition of Hep D
HDV a defective virus may onlu co-infect with HBV or superinfect people who are already carriers of HBV
incomplete DNA virus - needs HBV for assembly
aetiology of Hep B
HBV is an enveloped, partially double-stranded DNA virus
transmission - sexual contact, direct contact, blood and vertical transmission
viral proteins produced:
- core antigen - HBcAg
- surface antigen - HBsAg
- e antigen - HBeAg - marker of increased infectivity
structure of HDV
single stranded RNA virus coated with HBsAg
patholgy of hep B and D
Ab and cell mediated immune responses to viral replication = liver inflammation and hepatocyte necrosis
HBV - inculbation 1-6mo
histology of hep B and D
variable
mild to severe inflammation and changes of cirrhosis
RF for HBV
IV drug use,
unscreened blood and blood products
infants of HBeAg +ve mums
sexual contact with HBV carriers
risk of persistent HBV varies with age - younger, esp babies more likely to develop chronic carriage
genetic factors associated with increased rates of viral clearance
haemophiliacs
MSM
haemodialysis pts and chronic renal failure
foster carers
close family members of a carrier or case
staff at institutions/prisons
adopted children from endemic area
epidemiology of hep B and D
common
350million worldwide infected with HBV
1-2million deaths/yr
common in SE asia, africa and mediterranean
HDV found worldwide
HBV relatively uncommon in UK
sx of HBV and HDV
incubation period 3-6mo
1-2wk prodrome
may have serum-sickness-type illness
jaundice with dark urine and pale stools
recovery 4-8wks
1% - fulminant liver failure
chronic carriage dx after routine LFT or if cirrhosis or decompensation develops
prodrome for HDV and HBV
malaise
headache
anorexia
nausea
vomiting
diarrhoea
RUQ pain
serum-sickness-type illness sx in HBV and HDV
fever
arthralgia
polyarthritis
urticaria
maculopapular rash
signs of acute HBV or HDV
jaundice
pyrexia
tender hepatomegaly
splenomegaly
cervical lymphadenopathy in 10-20%
occaisionally urticaria/maculopapular rash
signs of chronic HBV and HDV
may be none
signs of chronic liver disease or decompensation
Ix for HDV and HBV
viral serology
PCR - detection of GBV DNA - most sensitive measure of ongoing viral replication
LFT - V high AST and ALT, high BR and ALP
clotting - high PT in severe
liver biopsy - percutaneous, or transjugular if clotting is deranged or ascites is present
viral serology of HBV and HDV
acute HBV - HBsAg +ve 1-6mo post exposure, IgM anti-HBcAg imply past infection
anti-HBsAg alone = vaccination
HBeAg present 1.5-3mo after acute illness - implies high infectivity
chronic HBV - HBsAg +ve, IgG anti-HBcAg. HBeAg +ve/-ve (-ve in precore mutant variant)
HBV cleared or immunity - anti-HBsAg +ve, IgG anti-HBcAg
HDV infection - detected by IgM or IgG against HDV
prevention of HBV and HDV
blood screening
instrument sterilisation
safe sex practices
passive immunisation
- hep B immunoglobulin (HBIG) following acute exposure and to neonates born to HBeg +ve mums - in addition to active immunisation
active immunisaton
- recombinant HBsAg vaccine for individuals at risk and neonates born to HBV +ve mums.
- immunisation against HBV protects against HDV
Mx of acute HBV hep
symptomatic treatment with bed rest, anti-emetics, anti-pyretics and cholestyramine for pruritis
notification to consultant in communicable disease control
managemnt of chronic HBV
indications for treatment with antivirals:
- HBeAg +ve or HBeAg -ve chronic hep (depending on ALT and HBV DNA levels - ie chronic liver inflammation)
- compensated cirrhosis and HBV DNA >2000IU/mL
- decompensated cirrhosis and detectable HBV DNA by PCR
INF-a (standard or pegylated whihc has an increased half life)
nucleoside/nucleotide analogues
avoid alcohol, immunise sexual partners
aim: clear HBsAg and prevent complications
nucleoside/nucleotide analogues
adefovir
entecavir
telbivudine
tenovir
lamivudine - less used because high resistence
INF-a for chronic HBV
cytokine - augments natural antiviral mechanisms
SE:
- flu like sx
- fever
- chills
- myalgia
- headaches
- bone marrow suppression
- depression
complications of HBV and HDV
fulminant hepatic failure - 1%
chronic HBV infection - 10% in adults, much higher in neonates
cirrhosis and hepatocellular ca
cholangiocarcinoma
extrahepatic immune complex disorders - glomerulonephritis, polyarteritis nodosa
cryoglobulinaemia
membranous nephropathy
superinfection with HDV may -> acute liver failure or more rapidly progressive disease
Px of HBV or HDV
in adults - 10% infections become chronic - of these 20-30% develop cirrhosis
factors predictive of a good response to INF:
- high serum transaminases
- low HBV DNA
- active histological changes
- abscence of complicating diseases
mx of HDV
INF-a has limited success - might need liver transplant
