Viral Hepatitis Flashcards
1
Q
Hepatitis A virus causes?
A
Hepatitis A
2
Q
Important properties of Hepatitis A
A
- Typical enterovirus classified in the picornavirus family
- Single stranded RNA genome
- Non enveloped
3
Q
Important properties of Hepatitis A
A
- Typical enterovirus classified in the picornavirus family
- Single stranded RNA genome
- Non enveloped icosahedral nucleocapsid & replicates in the cytoplasm
- Also known as enterovirus 72
- has one serotype
- No antigenic relationship to HBV or other hepatitis viruses
4
Q
Transmission for Hepatitis A
A
*
5
Q
Transmission for Hepatitis A
A
- Fecal-oral route, unlike HBV rarely transmitted via blood
- Humans are reservoir
- Virus appears in feces two weeks before symptoms so quarantine of patients is ineffective
- Children most recently infected
- Outbreaks occur in special living situations (summer camps, boarding schools)
- Common source outbreaks arise from fecaly contaminated water or food such as oysters grown in polluted water & eaten raw
- 50-75% of adults have been infected
6
Q
Pathogenesis of Hepatitis A
A
- Not completely understood
- Probably replicates in GI tract & spreads to liver via blood
- Hepatocytes infected but mechanism by which cell damage occurs is unclear
- Hepatitis caused by different viruses can’t be distinguished pathologically
- Immune response consists of IgM antibody which is detectable at the time jaundice appears
- IgM followed 1-3 weeks later by production of IgG antibody which provides lifelong protection
7
Q
Clinical findings for Hepatitis A
A
- Hepatitis virus findings are virtually the same from all
- Fever, anorexia, jaundice, vomiting, nausea are typical
- Dark urine, pale feces, elevated transaminase levels
- Most cases resolve spontaneously in 2-4 weeks in contrast to Hep B which is 10-12 weeks
- Most asymptomatic & detectable solely by presence of IgG antibody
- No chronic hepatitis or carrier state occurs
- No predisposition hepatocellular carcinoma
8
Q
Laboratory diagnosis for hepatitis A
A
.
9
Q
Laboratory diagnosis for hepatitis A
A
- Detection of IgM antibody is most important test
10
Q
Treatment for hepatitis A
A
- No antiviral therapy available
- Active immunization with a vaccine containing inactivated HAV available
- 2 doses, initial dose followed by booster 6-12 months later
- Vaccine recommended for travelers to developing countries, for children 2-18 yrs, and men-men sex
- If unimmunized person must travel to endemic area w/in 4 weeks then passive immunization should be given to provide immediate protection & the vaccine given to provide long term protection
- Many adults have
11
Q
Treatment for hepatitis A
A
- No antiviral therapy available
- If unimmunized person must travel to endemic area w/in 4 weeks then passive immunization should be given to provide immediate protection & the vaccine given to provide long term protection
- Many adults have antibodies to HAV
- Passive immunization w/immune serum globulin prior to infection or w/in 14 days after exposure can prevent or mitigate the disease
12
Q
Prevention for hepatitis A
A
- Active immunization with a vaccine containing inactivated HAV available
- 2 doses, initial dose followed by booster 6-12 months later
- Vaccine recommended for travelers to developing countries, for children 2-18 yrs, and men-men sex
- Observation of proper hygiene (sewage disposal, proper hand washing after bowel movements)
13
Q
What disease does HBV cause?
A
HBV causes hepatitis B
14
Q
Important properties of HBV
A
- Member of the hepadnavirus family
- 42 nm DNA enveloped virion
- Icosahedral nucleocapsid core containing partially double stranded circular DNA genome
- Envelope contains protein called surface antigen
- DNA Dependent DNA polymerase
- Genome contains 4 genes that encode 5 proteins
- S gene encodes surface antigen
- C gene encodes core antigen and e antigen
- P gene encodes polymerase
- X gene encodes x-protein (activator of viral RNA transcription)
15
Q
What does the core antigen and e antigen do for HBV
A
Core antigen: Forms nucleocapsid core of virion
E antigen: Secreted from infected cells into the blood, important indicator of transmissibility
