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34 Cards in this Set
- Front
- Back
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What is Encephalitis?
Meningitis? Aseptic Menigitis? |
Encephalitis - infection of brain parenchyma (neurons, glial cells)
Meningitis - Infection on meniges (dura mater, arachnoid mater, pia mater) Aseptic Menigitis - Viral infection of meniges |
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What is Myelitis?
Encephalomylitis? |
Myelitis - infection of spinal chord
Ecephalomyletis - infection of brain and spinal chord |
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What are the 2 main ways that a virus can enter the CNS?
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1. Hematogenous route - direct infection of endothelial cells, entry at choroid plexus due to lack of tight junctions, or entry via migration of an infected inflammatory cell
2. Neural Route - anterograde movement in axons from site of infection (HSV, rabies), olfactory nerve endings |
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What are the common clincial symptoms of encephalitis?
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- Acute onset of febrile illness with headache and altered mental status
- Key: early mental status changes, can be focal or diffuse Note: Difference from meningitis is that BEHAVIORAL CHANGE is more likely than fever |
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What 2 viruses can cause encephalitis?
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1. HSV most common cause of sporadic encephalitis
2. WNV most common cause of epidemic encephalitis |
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What are the clinical signs of meningitis?
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Classic Triad:
1. Headache 2. Fever 3. Neck Stiffness |
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What are the 3 viruses that can cause aseptic meningitis?
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1. Enteroviruses
2. HSV-2 3. Mumps (rarely) |
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Which ganglion often harbors HSV-1?
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Trigeminal ganglion
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What is the most common cause of sporadic encephalitis?
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HSV-1
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What is the mortality rate of HSV encephalitis?
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70%
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What is the treatment for HSV sporadic encephalitis?
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IV acyclovir for 14-21 days
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How is HSV encephalitis diagnosed?
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MRI scans - looks for FRONTO-TEMPORAL lesions
Lumbar puncture - detect viral DNA in CSF |
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What are the cellular characteristics of Rabies Virus?
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- rhabdovirus
- enveloped - -ssRNA - BULLET SHAPED |
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How is rabies virus detected?
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Detect in corneal test (find rabies antigen in corneal smears)
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Which animal is the most common vector for human rabies?
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- The bat
- Can also be transmitted by raccoon, skunk, foxes. |
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What is the pathology for rabies virus?
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1. First centripetal spread from muscle, through nerve, to CNS
2. Then centrifugal spread from CNS to cornea and salivary glands |
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What cellular abnormality is seen in rabies victims upon autopsy?
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Negri Bodies
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What are the symptoms of rabies?
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- 4-6wk asymptomatic incubation period
- prodrome phase of flu like symptoms - neurologic phase of anxiety, confusion, agitation, hydrophobia - Coma, DEATH (almost universally fatal) |
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What is the treatment for rabies?
Vaccine? |
- Ig for post-exposure immunoprophylaxis
- Inactivated vaccine for pre and post exposure |
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What are the cellular characteristics of West Nile Virus (WNV)?
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- Flavavirus (like HCV)
- Arbovirus (insect transmission) - enveloped - +ssRNA |
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What is an arbovirus?
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Any virus that is spread between animals via biting insects such as mosquitoes and ticks
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What are the symptoms of WNV?
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Mostly asymptomatic
- 20% infected get West Nile Fever (flu) - 1% get encephalitis - 10% mortality |
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What is the Tx for WNV?
Vaccine? |
No Tx or Vaccine
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What is the most common cause of epidemic encephalitis?
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WNV
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What are the cellular characteristics of Polio?
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- Enterovirus
- Non-enveloped - +ssRNA |
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What is the pathology of Poliovirus?
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- Replicates in Peyer's patches
- Excreted in feces - Viremic spread to CNS, prefers anterior horn cells (motorneurons) |
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How is polio spread?
When was it eradicated in the US? |
Spread via oral-fecal
Eradicated in 1979 |
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What are the symptoms of Poliovirus?
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- 90% asymptomatic
- 1% results in flaccid paralysis and loss of muscle tone |
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What is the Tx for polio?
Vaccine? |
- No Tx
- Live oral vaccine: Sabin very effective but can cause polio - Inactivated vaccine (salk, 4 doses, no "bystander" effect) |
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What are the cellular characteristics of Prions?
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Not a virus but a Prion Protein (PrP)
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What is the pathology of Prion?
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- misfolding of PrP forms aggregates in CNS
- Could be caused by mutation in own PrP gene, or infection by mutant PrP that causes normal PrP to misfold - Causes spongiform lesions and astrocytic gliosis |
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How are prions spread?
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1. Dietary consumption of affected organisms
2. Genetically in germline mutations (familial CJD) 3. Organ Transplants (iatrogenic CJD) |
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What are the symptoms of Prions?
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- Long incubation (years)
- Creutzfeldt-Jackob disease in humans |
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What is Bovine Spongioform encephalopathy
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Mad Cow Disease. When in Britians cows ate themselves via the feed
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