Hepatitis A

(Class, Replication, Pathogenesis?)

Class-Picornavirus (Icosahedral Capsid positive sense ssRNA)

Replication-Binds to specific Liver receptors and is non-cytolytic

Pathogenesis- Enters bloodstream through oropharynx, replicates in hepaticytes/kupffer cells, and viruses are shed into bile-->stool 10 days prior to jaundice or antibody detection

IFN slows replication CD8+ are needed to kill infected cells. Antibody and complement facilitate clearance. Only causes Acute infection

Hep A

(Epidemiology, Clinical Syndromes)

• 40% of Acute Cases of Hepatitis, contagious 10-14 days b4 symptoms (increase spread). 
• -20-50% have inapparent but productive infection
• Fecal-Oral
• Very resistant (60C, Detergent, pH 1)
• Epidmenics usually from common source ie Water, Daycare, Resaurant

Hep A

(Clinical Symptoms)

• Abrupt Symptoms 15-50 days post infection and intensify 4-6 days prior to icteric phase
• Symptoms- Fever, fatigue, nausea, loss of appetite,
• Dark urine, pale stool, Jaundice (70-80% adults 10% of kids)
• Viral Shedding starts 14 days prior to sym and stops before the end of symptoms. Usualy recover w/in 2-4 weeks of onset
• Fulminant in 1 per 1000 (80% mortality)

Hep A

(Dx, Tx)

Anti-HAV IgM (ELISA), Radioimmunoassay

TX

• Avoid Contaminated water/food (esp uncooked shellfish). Proper hand washing
• Prophylaxis IgG 80-90% effective
• Killed HAV vaccine to infants 2 years of age with HBV

Hep B

(Structure And Replication)