Viral Hepatitis
description
Transcript of Viral Hepatitis
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Viral Hepatitis
AA“Infectious”
“Serum”
Viral hepatitis
Entericallytransmitted
Parenterallytransmitted
F, G,? other
EE
NANB
BB DD CC
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Hepatitis A Virus
• Naked RNA virus• Related to enteroviruses, formerly known as
enterovirus 72, now put in its own family: hepatovirus • One stable serotype only• Difficult to grow in cell culture: primary marmoset cell
culture and also in vivo in chimpanzees and marmosets
• 4 genotypes exist, but in practice most of them are group 1
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Incubation period: Average 30 days
Range 15-50 days Jaundice by <6 yrs, <10%
age group: 6-14 yrs, 40%-50%>14 yrs, 70%-80%
Complications: Fulminant hepatitisCholestatic hepatitisRelapsing hepatitis
Chronic sequelae: None
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FecalHAV
Symptoms
0 1 2 3 4 5 6 12
24
Hepatitis A Infection
Total anti-HAV
Titre ALT
IgM anti-HAV
Months after exposure
Typical Serological Course
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• Close personal contact
(e.g., household contact, sex contact, child day care centers)
• Contaminated food, water(e.g., infected food handlers, raw shellfish)
• Blood exposure (rare)(e.g., injecting drug use, transfusion)
Transmission
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EndemicityDisease
RatePeak Age
of Infection Transmission Patterns
High Low to High
Early childhood
Person to person;outbreaks uncommon
Moderate High Late childhood/
young adults
Person to person;food and waterborne outbreaks
Low Low Young adults Person to person;food and waterborne outbreaks
Very low Very low Adults Travelers; outbreaks uncommon
Global Patterns of Hepatitis A Virus Transmission
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Diagnosis
• Acute infection is diagnosed by the detection of HAV-IgM in serum by EIA.
• Past Infection i.e. immunity is determined by the detection of HAV-IgG by EIA.
• Cell culture – difficult and take up to 4 weeks, not routinely performed
• Direct Detection – EM, RT-PCR of faeces. Can detect illness earlier than serology but rarely performed.
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Hepatitis E virus
Hepeviridae Hepevirus
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Hepatitis E Virus
• unenveloped RNA virus, 32-34nm in diameter
• +ve stranded RNA genome, 7.6 kb in size.
• very labile and sensitive
• Can only be cultured recently
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Incubation period: Average 40 days
Range 15-60 days Case-fatality rate: Overall, 1%-3%
Pregnant women, 15%-25%
Illness severity: Increased with age
Chronic sequelae: None identified
Hepatitis E - Clinical Features
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Symptoms
ALT IgG anti-HEV
IgM anti-HEV
Virus in stool
0 1 2 3 4 5 6 7 8 9 10
11
12
13
Hepatitis E Virus InfectionTypical Serologic Course
Titer
Weeks after Exposure
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Most outbreaks associated with faecally contaminated drinking water.
Several other large epidemics have occurred since in the Indian subcontinent and the USSR, China, Africa and Mexico.
In the United States and other nonendemic areas, where outbreaks of hepatitis E have not been documented to occur, a low prevalence of anti-HEV (<2%) has been found in healthy populations. The source of infection for these persons is unknown.
Minimal person-to-person transmission. Risk groups for severe course: Pregnancy, DM, obesity,
hypertension, ischemic heart disease
Hepatitis E - Epidemiologic
Features
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Genotype 1
(Burma)
Genotype 2
(Mexico)
Genoytpe 3
(USA-swine)
Genotype 4
(China)
-causes epidemies
- subtropical regions
-Transmitted with contaminated water
- ın Europe travel associated
-Reservoir: Human
-Sporadic cases
- worldwide distributed (except Africa)
-Zoonotic
-In Europe: autochton
-Reservoir: wild boar
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Epidemiological features of hepatitis E in disease-endemic areas
Large outbreaks involving several hundred to several thousandpersons in developing countries
Sporadic hepatitis cases frequent
Fecal–oral transmission (usually through contaminated water) is thepredominant route of transmission
Insignificant person-to-person transmission
Parenteral transmission known but appears to contribute to only aminority of cases
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• Mother-to-newborn (transplacental) transmission known
• Highest attack rate among young adults aged 15–40 years, with• relative sparing of children
• High attack rate and mortality among pregnant women, particularlythose in second and third trimesters
• Low overall case fatality rate
• Chronic infection ? Immunosuppression?
• Superinfection can occur among persons with chronic liver disease
• Overall attack rates during hepatitis E outbreaks have rangedfrom 1% to 15%.
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• Diagnosis
Detection of anti-HEV IgM and IgG
Detection of virus RNA (rarely applied)
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• PreventionPossibly contaminated drinking water should be avoided as should uncooked food in endemic areas.
• Immune globulin is not effective if it comes from donors in western countries.
• There is no vaccine.