Arboviruses
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- What family do EEE, VEE, and WEE belong to? What is the structure of their virion and genome?
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*togaviruses (alphavirus genus)
*enveloped icosahedral nucleocapsid
*(+) ssRNA - What is the vector for WEE/VEE/EEE? Describe the path of these viruses after transmission from the vector.
- After transmission from a mosquito, the virus moves from the blood to endothelial cells and then into nerve cells.
- Describe the clinical presentation of EEE.
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*10-12 day prodromal febrile illness
*fever, stiff neck, mental status changes
*seizures and coma are possible
*progression to encephalitis carries a 50-75% mortality - How does EEE cause pathogenesis?
- The infection induces apoptosis in host cells.
- What is the reservoir for EEE? Why is this fact useful for epidemiological purposes?
- Wild birds are asymptomatically infected and serve as a reservoir. Sentinal birds can thus be used to track disease patterns.
- What family does St. Louis encephalitis belong to? What is its virion and genome structure?
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*flavivirus
*enveloped, icosahedral nucleocapsid
*(+) ssRNA - Other than a subclinical infection, what are the three main manifestations of SLE?
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1.Encephalitis
2.Meningitis
3.Febrile headache - What patient population is prone to a more severe disease course with SLE?
- The elderly - they become symptomatic and have mortality from SLE that is ten times that of younger people.
- What are the components of the sylvatiic and the urban cycles of transmission of SLE?
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*sylvatic cycle includes mosquito vector, bird reservoir/amplifying host, and human host
*urban cycle includes mosquito vector and human host - During what time of year is SLE most likely to be seen? About how many cases are seen in the US annually?
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*July-September (coinciding with mosquito prevalance)
*~50 cases/year - How is SLE diagnosed?
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*PCR detection of virus in blood, CSF or tissue
*ELISA detection of specific IgM
*immunofluoresence of SLE Ag in urine or CSF - How is SLE treated? How can it be prevented?
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*treatment is supportive only
*there is no vaccine so prevention is limited to vector control - What family does West Nile virus belong to?
- Flaviviruses
- How is WNV transmitted?
- Most often from the bite of a viremic mosquito but has also been transmitted via contaminated organs or blood products.
- What are the ramifications of WNV infection during pregnancy?
- Intrauterine infection and congenital abnormalities.