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Roseola, 5th disease, coxsackie


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What virus causes roseola? What family does this virus belong to?
*human herpes virus 6 (HHV-6)
*herpes viruses
What is the clinical presentation of roseola?
*rapid onset of high fever and red rash which resolves in 3-5 days
*many cases may be asymptomatic
What is the structure of the roseola virion and genome?
*icosahedral capsid with an envelope
*genome is dsDNA
What complications often arise from reactivation of latent roseola?
In fact, there is no pathogenesis associated with reactivation of the latent form.
How is roseola transmitted? Where does the initial infection and replication occur?
*it is transmitted by salivary droplets, so close contact is required
*initial infection and replication is in the oropharynx
How common is infection with roseola?
Nearly universal - the vast majority of infants are seropositive by 13 months, though most primary infections are subclinical or asymptomatic.
How is roseola treated? What prevention is available?
Treatment is usually unwarranted, but ganciclovir or acyclovir can be used in immunosuppressed patients. There is no vaccine.
What is the causative agent of 5th disease? What is the structure of the virion and genome of this virus?
*parvovirus B19
*naked icosahedral capsid surrounding one molecule of (+) or (-) ssDNA
Where does the virus that causes 5th disease replicate? What does its replication depend on?
It replicates in the nucleus and must use the host cell's machinery...for this reason, viral replication occurs only when the host cell is in S phase.
What is the childhood presentation of 5th disease? What symptoms might adults show? What happens with in utero infection?
*peds have characteristic rash on face (and possibly trunk) and low-grade fever
*adults may have arthalgia due to deposition of Ag-Ab complexes following flu-like illness
*in utero infections may cause spontaneous aboortion, though surving fetuses are usually unaffected
What population of patients are at risk for serious disease with infection by the virus that causes 5th disease? What condition is likely to occur?
Parvovirus B19 can cause an aplastic crisis in patients with hemolytic disorders.
The virus that causes 5th disease is specifically cytotoxic to what cells?
Erythropoetic cells in the bone marrow, fetal heart and liver.
How is the virus that causes 5th disease spread?
Respiratory droplets.
What family does coxsackie virus belog to? how many serogroups and serotypes of this virus exist?
*30 serotypes divided between 2 serogroups
Which serogroup of coxsackie virus generally causes more severe disease?
*infections with serogroup B are more serious than those with serogroup A
What is the viral and genomic structure of the coxsackie virus? Where in the host celll does this virus replicate?
*naked, icosahedral capsid
*genome is one mole cule of (+) ssRNA
*viral replication occurs in the cytoplasm
How is coxsackie virus transmitted?
It can be transmitted by either the fecal-oral or repiratory route.
What are some of the clinical presentations of infection with serogroup A of coxsackie virus?
*hand, foot and mouth disease
*aseptic meningitis (typically mild)
*infantile diarrhea
*usually less severe than group B
What are some of the clinical presentations of infection with serogroup B coxsackie virus?
*respiratory or cardiac disease in neonates
*typically more severe than group A
With what chronic disease has coxsackie virus been associated?
Juvenile (type 1) diabetes mellitus.
How does infection with coxsackie virus affect the development of immunity to other agents?
Infection with coxsackie virus can interfere with the development of antibodies to other picornaviruses, most notably polio.
What is the difference between a serotype and a serogroup?
*members of a serotype will be neutrallized by the same antibody
*members of a serogroup will react to, but not be neutralized bby, the same antibody

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