Hepatitis A and B Overview

Hepatitis A

• Cause: HAV - Picornaviridae
• Marker of acute Hepatitis A: IgM anti-HAV
• Peak of illness: During first month
• Duration of decline: 6 to 12 months
• Detection method: Solid-phase antibody capture ELISA, competitive inhibition ELISA
• Transmission: Fecal-oral route
• Incubation period: 28 days
• Disease course: Acute and self-limiting; no carrier state
• Diagnosis: Liver function tests (ALT), total bilirubin, anti-HAV detection via enzyme immunoassay (EIA) or radioimmunoassay (RIA)
• Prevention: Immunoglobulin injections within 2 weeks of exposure for household and sexual contacts of infected individuals

Hepatitis B

• Cause: HBV - Hepadnaviridae
• Transmission: Sexual contact, blood
• Incubation period: 60 to 90 days
• Disease course: Can be acute, chronic, or fulminant; or asymptomatic carrier
• Symptoms: Similar to HAV infections
• Markers: HBsAg (Hepatitis B surface antigen), HBeAg (Hepatitis Be antigen), HBcAb (Hepatitis B core antibody), HBeAb (Hepatitis Be antibody), HBsAb (Hepatitis B surface antibody); order of appearance tracked
• Prevention: Avoidance of high-risk behaviours, HBV vaccination

Hepatitis C

• Infection: Acute, chronic, or previous infection
• Detection: Recombinant immunoblot assay (RIBA) or molecular method
• Viral load testing: Used in blood/organ donor screening
• Genotyping: Determines optimal treatment
• Markers: HCV RNA, anti-HCV
• Other important factors: HDV (defective virus requires HBV), HEV (fecal-oral, self-limiting)

Hepatitis D

• Cause: Defective virus
• Requires HBV: For replication and expression
• Types: Co-infection with HBV, super-infection
• Markers: IgM anti-HDV, IgG anti-HDV, HDV RNA
• Associated risks: High mortality rate in pregnant women (20-25% due to complications)

Hepatitis E

• Transmission: Fecal-oral route
• Incubation period: 2-6 weeks
• Common symptoms: Often silent, all genotypes cause acute hepatitis with indistinguishable symptoms from other hepatitis types

Hepatitis Virus Summary

• Disease: Inflammation of the liver
• Types: HAV, HBV, HCV, HDV, HEV
• Transmission: Fecal-oral, blood-borne, sexual contact
• Markers: Antibody levels, specific antigens
• Diagnosis: Liver function tests, serological markers, viral load
• Prevention: Vaccination, avoidance of high-risk behaviors, safe practices

HIV

• Types: HIV-1 (Clades M, N, O), HIV-2 (Subtypes A-E)
• Transmission: Sexual contact, blood and body fluids, perinatal
• Symptoms: Initial flu-like symptoms, followed by an asymptomatic period; opportunistic infections may manifest later.
• Diagnosis: ELISA, rapid tests, western blot, HIV-1 viral load, CD4 T-cell counts.
• Viral Load: HIV RNA in the blood.
• CD4 count: Shows how CD4 cells have been affected; used to monitor progress.
• Treatment: Antiretroviral therapy (ART).