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Hepatitis A (Clinical Features (depends on age (younger = less likely to…
Hepatitis A
Clinical Features
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Prodromal phase (1-7d) - nonspecific sx: fever, fatigue, malaise, anorexia, abdo pain, N+V
Symptomatic phase (3 weeks) - Bilirubinuria, Pale/clay colored feces and jaundice; liver enlargement; jaundice typically indicates resolution of symptoms.
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Overview
Family: Picornaviridae, Genus : Heparnavirus
Structure: Icosahedral, enveloped (blood) OR non-enveloped (feces), +ve sense RNA
Antigenicity: One serotype (can make a vaccine), 4 genotypes in humans
Epidemiology:
- closely linked to SEG
- Global shift towards lower endemicity resulting in increased age of infection + therefore increased disease burden.
Pathogenesis
Life cycle:
Replication takes place in cytoplasm. +ve sense RNA translated to produce polyprotein which is cleaved into structural (make capsid) or replicative (make RNA) proteins. Released from cell by budding.
Virulence factors:
- Enveloped - exits cell without lysis, immune evasion
- Non-enveloped (outside body) - stability and transmission
- Resistance to heat (<85C), organic solvents/detergents, low pH (withstand acid in stomach).
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Gets into blood via stomach and crosses intestine into blood. Heads to liver. Grows slowly in hepatocytes + Kuffer's cells and is non-cytolytic. Immunopathology mediated liver damage (cytotoxic T cells).
Complications
Cholestatic hepatitis - fever, pruritus, prologed jaundice
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Diagnosis
Serology and LFT (e.g. ALT)
- anti-HAV IgM +ve - acute infections
- anti-HAV IgG +ve - chronic, previous, vaccinated
Hepatitis E
Complications
Neuro: Guillain-Barre, Bell’s palsy, acute transverse myelitis, acute meningoencephalitis
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Muscular: arthralgia, myalgia
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Clinical Features
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Sx typically prodromal then more specific: fever, nausea abdominal pain, jaundice
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Overview
Family: Hepeviridae, Genus: Orthohepevirus (Mammalian)
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Epidemiology: link with lower SEG (ip HEV 1/2). HEV 3/4 outbreaks seen in developed regions. Typically seen in young adults (19-30yrs). Relatively low in children.
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Pathogenesis
Transmission:
- Fecal/oral route (HEV1+2)
- Zoonotic transmission (HEV 3/4), blood + blood products, vertical
Diagnosis
Serology (Anti-HEV IgM), IgM +ve confirmed by Molecular tests