CNS Viral Infections Flashcards
What type of meningitis is most common overall?
Viral is more common, but bacterial can be deadly, so important to distinquish
In how many days does a viral meningitis usually resolve?
7-10 days
What types of virus cause 80% of viral meningitis?
Enterovirus–> Echo, Coxsackie, Enterovirus 71
What virus is responsible for recurrent aseptic meningitis usually?
Herpes simplex virus-2 (HIV or VZV also can cause)
What are 5 symptoms of viral meningitis?
- Fever
- Malaise
- Headache
- Stiff neck
- Low back pain (usually overshadowed by headache)
What disease can cause viral meningitis due to not being vaccinated?
Mumps
What category of viruses cause 30% of viral encephalitis?
Arborviruses–> these are transmitted by a zoonotic vector, usually mosquitos or ticks, so have a strong seasonality
What type of viruses cause viral encephalitis and may cause mini-epidemics within families?
Enteroviruses (echo, coxsackie, enterovirus 71)
What virus causes a little over a quarter of cases of viral encephalitis and may be fatal if not treated?
Herpes Simplex virus-1–> tx with acyclovir
*70% mortality w/o tx = DO NOT MISS
What part of the brain is preferentially affected by herpes viral encephalitis?
Temporal lobe–> causes hemorrhagic necrosis; can be visualized via MRI
What causes HSV encephalitis generally (mode of infection)?
More often due to reactivation of latent virus than by initial acute infection
Other than MRI findings, what finding can be suggestive of Herpes encephalitis?
RBCs in the CSF
Definitive test for dx of HSV encephalitis?
PCR (false negatives do occur though)
Flaviviridiae cause what three human diseases?
- St. Louis encephalitis
- West Nile
- Japanese encephalitis
Flaviviridiae are small, ________, _________, ___ strand ____ viruses
Enveloped, nonsegmented, (+) RNA viruses
Flaviviridiae have their RNA translated by host ribosomes into a single polyprotein.. what are the fragments cleaved by host proteases called? Fragments cleaved by viral proteases?
Host protease–> trans
Viral–> cis
Where do flaviviridiae first replicate in the host? After the transient primary viremia where do they travel to and replicate?
Initially replicate in the endothelium or epithelial cells surrounding the bite site, then after primary viremia replicate in spleen, lymph nodes and macrophages (occurs 3-7 days post exposure)
How do Flaviviridiae end up causing encephalitis?
If the infection is not controlled by the immune system following the primary viremia, then a secondary viremia occurs and results in the severe systemic disease (encephalitis)
What three clinical syndromes can occur with St. Louis encephalitis?
- Febrile headache
- Aseptic meningitis
- Encephalitis
*in 80s and 90s outbreaks have occurred in Colorado, California, Texas, Florida, and Arkansas
After initial onset of symptom in St. Louis encephalitis including malaise, fever, headache, sore throat or cough, what symptoms can occur in 1-4 days indicating severe disease?
acute or subacute meningeal and neurological signs
What is treatment for SLE?
None.. there are no vaccines and antiviral therapy has not been evaluated. Mosquito control is the best means of control
*Fatality rate is low, but those that have fatal infections usually die within 1-2 weeks
How does the West Nile virus get into mosquitoes?
Mosquitoes get from feeding on birds, the virus then replicates in the salivary glands of the mosquito
Most infections with West Nile virus usually only have what 4 symptoms?
- febrile headache
- myalgia
- skin rash
- swollen lymph nodes
* only 1% will develop serious systemic disease
What symptoms are seen in patients that get severely ill from West Nile?
- Severe headache with high fever
- Neck stiffness, muscle weakness
- Stupor, disorientation, convulsions, tremors
- Coma, paralysis, and rarely, death
