hepatitis Flashcards
HBV
most important pathogen among hepatitis viruses
only DNAvirus
family hepadnaviridae
genus-orthohepadna virus
commonly asymotomtic or subclinical but
complications- chronic hepatitis,cirrhosis of liver,chronic hepatitis and liver cancer(HCC)
morphology of HBV
3 forms seen in HBsAg reactive serum
1)22nm spherical form-HBsAg(most numerous)
2)tubular or filamentous forms-overproduction of HBsAg
3)Complete form of Dane particle 42 nm spherical virion
-outer surface(HBsAg) surrounds inner nucleocapsid core (core pr HBcAg and precore pr HBeAg)
-viral genome- partially double stranded circular DNA
L strand (-) complemetary to all HBV and mRNA
S (+) strand is variable
DNA polymerase in core
HBV serological markers
🎀HBsAg: First serologic marker
disappear with clinical improvement
HBsAg+ IgM anti-HBc = acute infection
Persistence beyond 6 months indicates chronic infection or carrier state
🎀AntiHBs Ab-Marker of recovery and immunity
detectable HBs Ag disappear and recovery is complete
indicate immunity after inoculation with hepatitis B vaccine or presence of antibody from HBIG
🎀IgM anti-HBc : Marker of recent acute infection, help to distinguish acute from chronic infection, usually present for upto 6 months and then become undetectable, simultaneously present with HBsAg indicate acute infection
🎀Anti-HBc: Indicate current or previous infection, not associated with recovery or immunity
🎀HBeAg: Marker of infectivity,
detectable in acute and chronic infection, persistence beyond 10 weeks indicates likely chronic liver disease, associated with HBV replication
🎀Anti-HBe : Presence in serum of HBs Ag carrier suggests lower titer of HBV and decreased infectivity
Antigenicity of HBV
HBsAg- Hepatitis B surface antigen
Antigenically complex
Consists of Group specific antigen - a
in addition to two pairs of mutually exclusive sub determinants d/y and w/r
4 phenotypes - adw ayw adr ayr
Useful in epidemiologic investigations as secondary cases have same subtype
HBcAg- Hepatitis B core antigen
Intracellular core pr, not secreted and not circulate in blood but can br demonstrated in hepatocytes by immunofluorescene
HBeAg: Hepatitis B e antigen
Major component of core pr
HBV replication and infectivity
Present in circulation
Lab Dx of HBV
Specific tests
-Serologic detection of HBV Ag and Ab
-HBsAg or AntiHBs - RIA / ELISA, particle agglutination
-HBV DNA in serum- PCR
Supportive tests
- Abnormal liver function- ALT > AST
Rise in ALT gradual rise andprolongation
-Liver Biopsy - Ts Dx
-WBC- Leukopenia followed by reactive leukocytosis
Clinical Features of HBV
Incubation period - 30 - 180 days
Slow and insidious onset
Sub clinical, Acute or chronic hepatitis
Clinical undistinguishable from other hepatitis
Pre - icteric phase= GI symptoms ( N,V)
Icteric Phase/ Jaundice = Carrier state or Recovery
Hepatic complication- fulminant hepatitis, cirrhosis of liver , HCC
Extra hepatic complication- serum sickness like syndrome ( arthritis rash angioedema haematuria proteinuria due to immune complex reaction)
Transmission of HBV
Parentral- IVDU, blood transfusion,organs transplant hemodialysis syringe tattoo razor piercing hospital personnel
Sexual - saliva semen menstrual fluid vaginal secretion
Vertical- pregnant women (chronic carriers) or acute in third trimester to infants , via breast milk or vaginal secretion if HBe Ag positive
Not transplacental
Prevention and Control of HBV
Specific measures
Active immunization (HBV)
Passive immunization( HBIG)
HBV vaccine- recombinant subunit vaccine
HBsAg in Baker yeast by DNA recombinant technology by cloning S gene into yeast chromosome
IM deltoid (20microg)
Infant (10microg)anteolateral thigh
3 doses at 6,,10,14 wk tgt with DPT
Additional at birth in endemic areas
Minimum interval 4 wk
Marker of protection- AntiHBs Ab > 10microIU/ml
Protection lasts for 30 yrs or longer
Revaccination - if anti HBs Ab < 10 microIU/ml at first series- HCW second vaccination
Non Low responders no further vaccination needed
Booster doses are not needed because memory cells get stimulated rapidly and titers rise very soon following exposure to HBV
Passive immunization HBIG
Indications- acutey exposed to HBsAg positive blood eg. Surgeons nurses
Sexual contact
Neonates borne to mother carrier
Post liver transplant
HBIG should be started immediately following accidental exposure not later than 7 days
Recommended dose 0.06 ml/kg or 10-12 IU/kg IM
Temporary protection for 3-6 months
Combined immunization of HBV
More efficacious than HBIG alone
Neonates borne to infected mom— 0.5 ml single injection HBIG immediately after birth followed by full course of vaccine ( 12hr ,1 m,6m)
Needle prick injuries- HBIG and HBsAg simultaneously at different sites to prevent neutralization of Ag and Ab
HAV
Family piconaviridae
Genus hepatovirus
Fecal oral route
Non envelope ssRNA not cross react
Pre icteric phase
Icteric phase( dark urine yellowish sclera mucus membrane
Complete recovery
Cx - Fulminant /Relapsing/ Cholestatic Heaptitis
Lab Dx of HAV
Anti HAV Ab detection
IgM Ab- acute phase
IgG Ab after Ig M and persists for decades
HAV Ag by ELISA +2-2 of jaundice
Prevention of HAV
Specific measures
Active immunization (HAV vaccine)/Passive immunization ( HAV IgA)
-HAV vaccine
All children more than 1 yr
Travellers to endemic
Chronic liver disease
2types
Formaldehyde inactivated vaccine-after 12 months
IM deltoid followed by booster 6-12months gap
Live attenuated vaccine SC
Highly immunogenic Long lasting immunity
Passive immunization- Human immunoglobulin- post exposure prophylaxis
Protection for 1-2 months
HCV
Genus Hepacivirus
First virus discovered by molecular cloning
Post transfusion hepatitis
Cirrhosis cancer
SsRNA
E1,E2
Hypervariable regions 1 and 2- hight rate of mutation
Genotype is important as response to antiviral therapy
Quasi species
B lymphocytes and hepatocytes
Risk factor alcohol coinfection with HBV and HIV
Biopsy gold standard for staging
No HCV vaccine
HDV or delta agent
Delta antigenHDAg surrounded by HBsAg envelope
RNA
Defective virus needs HBscoat for transmission
Coninfection with HBV
Parental
Prevented by HBB vaccine
