Page 443 - Concise Pathology for Exam Preparation ( PDFDrive )

428 SECTION II Diseases of Organ Systems

3. Delta hepatitis (hepatitis D)
Aetiology
• It is caused by hepatitis D virus (HDV), which is a defective RNA virus. The RNA
genome is encapsulated or covered by an outer coat of hepatitis B surface antigen.
• It requires hepatitis B virus for replication and expression.
• Incubation period is 1–4 months.
• HDV RNA is detectable in the blood and liver just before and during acute symp-
tomatic disease.
• HDV can infect a person simultaneously with HBV (coinfection) or it may super
infect a person who is already a chronic carrier of HBV (super infection).
• Acute coinfection by HBV and HDV is best suggested by presence of IgM against
both HDAg and HBcAg.
Epidemiology
Two epidemiological patterns exist:
• Predominant transmission by nonparenteral route, especially close personal contact
(endemic areas)
• Predominant transmission by parenteral route, ie, persons exposed frequently to
blood and blood products, mainly intravenous drug addicts and haemophiliacs
(nonendemic).
4. Hepatitis C
Aetiology
• Formerly called blood-borne, non-A and non-B hepatitis, it is a single-stranded RNA
virus belonging to the family Flaviviridae. It shows a lot of genomic instability and
antigenic variability, thereby making it difficult to develop a vaccine against it.
• HCV RNA can be detected in the course of infection, well before the appearance of
antibodies to HCV.
Epidemiology
• Incubation period is 6–8 weeks.
• HCV is the cause of greater than 90% cases of post-transfusion hepatitis. Perinatal
and sexual transmission can occasionally be seen.
• Carrier state is quite common with hepatitis C infection.
• Anti-HCV antibody is found to be positive in more than 50% cases of unexplained
cirrhosis or hepatocellular carcinoma.
5. Hepatitis E
Aetiology
• It is a nonenveloped single-stranded RNA virus belonging to the Hepevirus genus.
• It is responsible for 40–60% cases of acute hepatitis in India. HEV antigen can be
identified in the cytoplasm of hepatocytes during active infection. The virus itself can
be isolated from the stools of the patient and anti-HEV IgG and IgM antibodies can
be detected in serum.
Epidemiology
• Incubation period is 4–5 weeks.
• Primary mode of transmission is enteric (epidemic, water-borne hepatitis). Source of
infection is animal reservoirs (monkeys, dogs, pigs and cats).
• A characteristic feature of HEV infection is the high mortality rate among pregnant
women.
6. Hepatitis G
• HGV is similar to viruses in the Flaviviridae family.
• Can be transmitted by blood transfusion.
• HGV coinfection is observed in 6% of chronic HBV infections and in 10% of chronic
HCV infections; however, whether HGV is actually pathogenic in humans remains unclear.

Clinically viral hepatitis evolves through the following stages: (i) asymptomatic,
(ii) acute and (iii) chronic.
Asymptomatic Phase

Patients are identified incidentally based on elevated aminotransferases or presence of
serological markers.

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