Hepatitis viruses:

Medical Virology
Hepatitis viruses: Dr. Jawad Kadhum Tarrad
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Etiology:
• 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 burnetii , Leptospira icterohemorrhagiae.
• Protozoal; Toxoplasma gondii.
• Drugs; analgestics(Aspirin), cardiacs(methyldopa), anesthetics (halothane), psychotropics(monoamine-oxidase inhibitors).
• Others as preganancy.

Important properties of Hepatitis viruses:
• All types of hepatitis viruses have RNA genome except HBV has DNA.
• All types of hepatitis viruses cause acute disease, while chronic disease caused by HBV,HCV and HDV.
• Pathogenesis is mainly dependent on immune response that causes liver damage, or on cytopathic effects.
Severity and duration of acute phase;
1. prodromal symptoms: fever , malaise, anorexia.
2. pre-icteric symptoms; nausea, vomiting ,abdominal pain,fever and chill.
3. icteric signs; jaundice , dark urine( due to bilirubinuria), and pale face( increase in serum levels of liver enzymes due to liver damage).

Hepatitis-A virus (HAV):
• It belong to family picornaviridae(pico=small genome, rna=RNA).
• Genome is (+)ssRNA.
• Capsid proteins are arranged in icosahedral(cubic).
• Non-enveloped (naked).
Transmission:
Humans are reservoir for HAV. It is transmitted by fecal-oral route. It is rarely transmitted via blood because level of viremia is low and chronic infection does not occur. Common-source outbreaks arise from ingestion of fecal contaminated water and food (such as oysters grown in polluted water and eaten raw).