Hepatitis viruses

College of Medicine Microbiology
Medical Virology
Hepatitis viruses: Dr. Jawad Kadhum Tarrad
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Etiology of hepatitis in general:
• Viral :
1. major ;they responsible for most cases of hepatitis that known as (hepatitis viruses)involve five types (A-E).
2. Minor ; yellow fever virus, CMV,EBV,rubella,Ebola, and others.
• Bacterial ; Coxeilla , Leptospira.
• Protozoal; Toxoplasma gondii.
• Drugs; analgestics(Aspirin), cardiacs(methyldopa), anesthetics (halothane), psychotropics(monoamine-oxidase inhibitors).
• Others as pregnancy.

Hepatitis-A virus (HAV):
• It belong to family picornaviridae.
• Genome is (+)ssRNA.
• Icosahedral(cubic).
• Non-enveloped (naked).
Transmission:
Humans are reservoir for HAV. It is transmitted by fecal-oral route during ingestion of fecal contaminated food and water. It is rarely transmitted via blood because level of viremia is low and chronic infection does not occur.
Pathogenesis:
HAV causes infectious hepatitis. HAV is acid-stable (acid-resistant) and can survive in GI tract. Following ingestion, the Virus probably replicates in epithelial cells of GI tract and spread to liver via blood and it cause liver damage. The virus is likely attack by cytotoxic T-cell that causes the damage to hepatocytes.

C/F:
HAV has short incubation period(3-6wk). Most cases are mild or asymptomatic. Most C/F : fever ,anorexia, vomiting, jaundice, dark urine, pale face. Children are most frequently infected group. HAV is responsible for only acute disease (no cause chronic , so no carriers of HAV) with sudden onset. Usually benign infection and complete recovery spontaneously within (2-4wk) in 99% of cases and confers lifelong immunity.