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12 Cards in this Set
- Front
- Back
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unique properties of parvovirus?
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smallest DNA virus, naked icos capsid, requires dividing cells to replicate, ssDNA
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describe parvovirus replication
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replicates in mitotically active cells, generates complementary DNA strand during S phase, needs dsDNA for viral txn and replication, plus or minus strand packaged in virion (all genes on plus strand)
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parvovirus epi? Specefically B19?
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respiratory droplets, contagious period precedes symptoms, nonenveloped virus resistant to inactivation, 50% infected by 15, 65% by 40, 90% of elderly
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describe the course of the virus w/I the host.
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B19 disease is biphasic: initial febrile phase hits URT epi cells first and is infectious then it moves to the marrow to infect dividing erythroid precursor cells, get viremia and cytolysis of em, then erythrocyte production stops which leads to chronic hemolytic anemia and can result in a life threatening aplastic crisis, the symptomatic stage is non infectious, it is immune mediated, the virus has almost been cleared, and a rash and/or arthralgia develops
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describe the clinical course of symptoms of the host.
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5 day incubation, viremia, virus in throat, flu like sx, drop in Hb, IgG and IgM appear, virus is cleared, then at day 20 develop rash and arthralgias
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what clinical syndromes are restricted to adults? Children? Pts with increased destruction of RBCs like sickle cell anemia? Immunodeficient patients?
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arthropathy due to acute or chronic infection. Erthema infectiosum (5th disease). Transient aplastic crisis. Persistent anemia in chronic cases
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what are the effects of infection of the fetus?
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fetal loss due to CHF (hydrops fetalis) and congenital anemia, seroneg mothers in 2nd trimester are at highest risk
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populations at risk?
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elementary school aged kids (most at risk), parents of children with B19, pregnant women (possible fetal infection), sickle cell anemia patients (aplastic crisis), immunocompromised
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describe erythema infectiosum (5th disease).
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4 to 15 yos, late winter to spring, asympto or nonspecefic to flu like, followed wi 7 days by slapped cheek rash, spreads from cheek to extremities
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diagnosis and treatment?
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parvo specefic IgG or IgM via ELISA, PCR or hybridization, no specefic antiviral therapy: can do immune globulin (severe cases with congenital immunodeficiency), anti inflammatories, isolation of hospitalized patients
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2 genera of parvo?
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erythrovirus (B19) and dependovirus (AAV)
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describe the dependovirus
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adeno associated viruses, asympto human infections, require complementation to replicate, propensity to integrate in host DNA, thus potential candidate vectors for gene therapy
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