Microbiology Cheat Sheet
Hepatitis Markers: Read the Pattern
Hepatitis marker interpretation for NEET-PG and FMGE: HBsAg, anti-HBc window period, vaccine vs natural immunity, HCV chronicity, and HEV in pregnancy.
MedNext Academy | 3 min read
Hepatitis Markers: Read the Pattern
Hepatitis marker interpretation for NEET-PG and FMGE: HBsAg, anti-HBc window period, vaccine vs natural immunity, HCV chronicity, and HEV in pregnancy.
This topic covers the comparative virology of hepatitis viruses A through E and the interpretation of hepatitis B serological markers in the evolution of infection.
High-yield lines
- Hepatitis A and E are transmitted by the faecal-oral route, while hepatitis B, C, and D are blood-borne.
- Hepatitis C has the highest chronicity rate at about 80 percent, while hepatitis E has the highest mortality in pregnant women at 15 to 25 percent in the third trimester.
- Hepatitis D is a defective satellite virus that requires the HBsAg envelope of hepatitis B to replicate.
- HBsAg is the first serological marker to appear, and its persistence beyond 6 months indicates chronic hepatitis B infection.
- During the window period, HBsAg has disappeared and anti-HBs has not yet appeared, so IgM anti-HBc is the only marker of recent acute infection.
- Vaccination produces only anti-HBs, while natural infection produces both anti-HBs and anti-HBc, since the vaccine contains only recombinant HBsAg.
- HBeAg is a marker of active viral replication and high infectivity, and seroconversion to anti-HBe indicates declining replication.
- Anti-HBc IgG total is a lifelong marker of prior HBV exposure and is never produced by vaccination.
- The risk of HBV chronicity is inversely proportional to age: about 90 percent in neonates, 25 to 50 percent in young children, and 5 to 10 percent in adults.
- HBV liver damage is immune-mediated by CD8 cytotoxic T cells, not by direct viral cytopathic effect.
- Anti-HAV IgM indicates acute hepatitis A, while anti-HAV IgG indicates past infection or vaccine-induced immunity.
- Anti-HCV antibody does not distinguish current from past infection, so HCV RNA by RT-PCR is essential to confirm active viraemia.
- HDV superinfection of a chronic HBV carrier leads to about 80 percent chronicity, whereas co-infection with acute HBV is usually self-limiting.
- HBV cccDNA persists in hepatocyte nuclei and is not eliminated by current antivirals, explaining viral persistence.
Mapped competency codes
- MI3.7
- MI3.8
Continue into the full chapter
This summary maps to MI3-gastrointestinal-and-hepatobiliary-system.
Frequently Asked Questions
Which marker is positive during the hepatitis B window period?
IgM anti-HBc is the only marker when both HBsAg and anti-HBs are negative, indicating recent acute infection.
How do vaccine-induced and natural HBV immunity differ serologically?
Vaccination produces only anti-HBs, while natural infection produces both anti-HBs and anti-HBc.
Which hepatitis virus has the highest chronicity rate?
Hepatitis C, with about 80 percent of infections becoming chronic, the highest among the hepatitis viruses.
Why is hepatitis E especially dangerous in pregnancy?
It causes fulminant hepatic failure with 15 to 25 percent mortality in the third trimester, a feature unique among hepatitis viruses.
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