AuCoin 4: + strand RNA enveloped viruses Flashcards
There are two subtypes of togaviruses. What are they?
alphavirus
rubivirus
What does rubivirus cause?
rubella
How is rubivirus transmitted?
via respiratory droplets or from mother to fetus transplacentally
Is rubella still seen in the US? Where is it still endemic?
no - eliminated in 2005; still seen in developing countries
**called “German measles”
Where does rubivirus begin replicating? Then where does it spread?
in the nasopharynx and lymph nodes; spreads via blood to internal organs and skin
What are the symptoms of rubivirus infection?
in children, usually mild symptoms including rash, low fever, nausea, conjunctivitis
infection during pregnancy (congenital rubella syndrome) causes significant malformations
How do you diagnose rubella clinically?
detection of IgM or 4-fold rise in IgG titers
What are viruses that are transmitted by arthropod vectors called? What is a common insect vector?
arboviruses; mosquito
What are common clinical features of arbovirus infections?
fever headache malaise encephalitis hemorrhagic fever
What are three ARBO viruses?
Togaviruses
Flaviviruses
Bunyaviruses
- *Think of Flava Flav wearing a toga with a nasty Bunyan
- *Toga and Flavi are icosahedral, while Bunya is helical
Alphavirus is a type of togavirus. What does it cause?
Eastern equine encephalitis
How is alphavirus, or EEE, transmitted?
it is an arbovirus, so from mosquitoes to wild birds to humans
- *Alpha the mosquito
- *infects horses
What are the symptoms of alphavirus (EEE) infection?
severe headaches nausea vomiting fever change in mental status seizures and coma **brain damage in survivors 33% mortality rate
How do you diagnose an alphavirus infection?
isolate the virus or detect rise in antibody titer
**no vaccine available, but there is one for horses
How is western equine encephalitis virus (WEE) different from eastern equine encephalitis virus (EEE)?
they are both arboviruses, both transmitted via mosquito to birds to humans - just know that WEE is less severe than EEE; no vaccine available for humans, but there is one available for horses
How is Venezuelan equine encephalitis virus (VEE) different from EEE and WEE?
they are all arboviruses; VEE is transferred from mosquitoes to horses to humans; found mainly in South and Central America; healthy adults get flu-like symptoms in addition to other symptoms; there IS a vaccine available for both humans and horses
Dengue virus is a flavivirus. How is it spread? Where is it found?
arbovirus - spread by mosquitoes; endemic in SE Asia, Central and South America, and Caribbean (not in US - except for imported cases)
What symptoms does dengue virus cause?
Dengue fever: breakbone fever - muscle and joint pain acutely febrile headache retroocular pain rash
Dengue hemorrhagic fever:
symptoms progress to prostration, GI and skin hemorrhage, shock and coma
How do you diagnose Dengue virus?
serological IgM
West Nile virus is also a flavivirus. How is it transmitted?
mosquito bite and infects CROWS
**Nile the Crow
How does West Nile virus spread throughout the body from the initial infection site? Who is most susceptible to this virus?
gets into the blood and spreads via monocytes/macrophages to the brain, which is the target organ; children and the elderly are at the greatest risk
What are some symptoms of West Nile virus?
less than 1% of cases are symptomatic, but symptoms range from flu-like to encephalitis: headache nausea fever malaise myalgia backache neck stiffness
How do you diagnose West Nile virus clinically?
virus-specific IgM in serum of CSF
St. Louis encephalitis is also caused by a flavivirus. How is it transmitted? Where is it seen?
mosquitoes bite infected birds; in the US in late summer/early fall
What are the symptoms of St. Louis encephalitis? Who is at risk?
flu-like febrile illness to encephalitis - can cause more severe neuroinvasive infections; elderly at risk
So, if it’s not West Nile virus, what else could you consider?
St. Louis encephalitis
Yellow fever virus is another flavivirus. How is it transmitted? Where is it seen?
arbovirus - transmitted by mosquitoes; seen in Africa and S. America (not US)
What are the symptoms of yellow fever virus?
hemorrhagic fever: jaundice fever headache BLACK vomit (hemorrhaging) hemorrhages
How fatal is yellow fever virus?
20-50% mortality!
**there is a highly effective live attenuated vaccine
Hep C virus is another flavivirus. How is it transmitted? Who is at high risk?
parenternally; IV drug users and organ transplant recipients
What is the most common indication of Hep C viral infection following a liver transplant?
cirrhosis - HCV infects hepatocytes and causes liver injury due to cytotoxic T cells
What are the symptoms of acute Hep C infection? Chronic?
primary infection can be asymptomatic or cause mild illness; acute infection causes decreased appetite, fatigue, nausea, muscle/joint pain, weight loss; cirrhosis which may lead to hepatocellular carcinoma
How is Hep C viral infection diagnosed clinically?
serology or RT-PCR for virion RNA
This virus is the SECOND leading cause of the common cold behind rhinovirus
coronavirus
What does coronavirus cause?
SARS: flu-like symptoms fever dyspnea hypoxia atypical pneumonia (bilateral lung infiltrates)
What are symptoms of a cold caused by coronavirus?
runny nose
sore throat
low grade fever
**limited to mucosal cells of respiratory tract
