Small Group: Viral CNS Disease Flashcards
Define meningitis.
Define encephalitis.
Define meningoencephalitis
inflammation of the meninges, the three membranes that envelop the brain and spinal cord: the dura mater, pia mater and arachnoid
inflammation of the brain
combination of the above 2 syndromes
Define myelitis and neuritis.
inflammation of the spinal cord and nerve respectively
- Name viruses that cause CNS infections int he U.S.
HSV 1,2 LaCrosse encephalitis Virus, St Louis encephalitis virus Western and Eastern equine encephalitis virus Venezuelan equine encephalitis virus Enteroviruses (Coxsackie virus, Echoviruses,Poliovirus) HIV Rabies virus West Nile virus Measles virus Mumps virus CMV
List the CNS viruses that can be treated with antiviral drugs.
HSV 1,2 CMV and HIV
List any vaccine available and describe their nature, indications for use and efficacy.
Vaccines are widely available for polio, measles, and mumps. Rabies vaccine is used for post-exposure prophylaxis and to prevent occupationally acquired infection. There are VEE vaccines available for horses and for humans likely to be exposed (i.e., vets, field workers, lab techs). There is an EEE vaccine available for horses. A virus that causes encephalitis in humans (seen frequently in Asia) also has a vaccine: Japanese B.
Describe how seasonality, age of patient and geographic location can be used as diagnostic tools for the enterovirus.
majority of cases of acute viral encephalitis are due to enterovirus (coxsackie and especially echoviruses)
contact with local swimming pool is a huge risk factor, family history of (viral) endocarditis is suggestive of cocksackie virus
Describe how seasonality, age of patient and geographic location can be used as diagnostic tools for the West nile
West nile virus typically results in an asymptomatic infection, but maybe severe in the elderly
Describe how seasonality, age of patient and geographic location can be used as diagnostic tools for the Herpes Simplex encephalitis.
no seasonality, rare and usually sporadic cases
List and describe laboratory tests that are appropriate and identify what they disclose.
lumbar puncture can be used to rule out bacterial causes of meningioencephalitis (in bacterial neutrophils are high, CSF glucose is low and CSF protein is high); CSF fluid can be used for culture and gram stain
PCR: enterovirus can be detected in CSF, West Nile virus antigen or genomic sequence can be detected in blood or CSF
CT (or MRI) can be used to screen for serious herniation risk; always used if patient is unresponsive
CBC: arrival encephalitis may show pleocytosis
viral serology: presence of West Nile IgM antibody (acute)
Explain the mechanisms of pathogenesis for enterovirus.
transmitted fecal oral route; replicates in the oropharnyx and gut, enters the blood stream and spreads to the brain and spinal cord; local inflammation results in symptoms
supportive care, no antiviral or vaccine available, generally self-limiting illness
Explain the mechanisms of pathogenesis for West Nile.
virus replicates in the reticuloendothelial system and primary viremia follows, in immunocompetent, healthy individuals, the primary viremia presents with febrile illness (without CNS involvement)
the secondary viremia more common in elderly leads to dissemination of the virus, primarily in the CNS, causing inflammation of the brain, scattered microglial nodules and perivascular inflammatory infiltrates of lympocytes
Acute WNV has been associated with acute flaccid paralysis
Explain the mechanisms of pathogenesis for HSV encephalitis.
HSV virus localizes to temporal lobe, likely to cause seizures and results in focal necrotizing infections
corticosteroids are not used in HSV, ventilator support may become necessary; high IV dose acyclovir will decrease morbidity and mortality, especially if used early; anticonvulsants are often helpful
Describe the characteristics and indications for vaccines against measles, mumps, polio and rabies.
measles (live attenuated, MMR), mumps (live attenuated, part of MMR) and polio vaccines (inactivated vaccine) are recommended for all children as part of the primary series
rabies vaccination is only administered (inactivated vaccine) after potential exposure
Discuss strategies to prevent viral infections affecting the CNS.
strict sanitation int he home, hand hygiene, temperature of dishwasher water; pools should regularly check chlorination levels
surveilence to detect arrival disease and public education about insect spread, DEET repellents
Describe how the various CNS viruses are transmitted to humans.
enterovirus are transmitted oral-fecal route
many ARBO viruses are transmitted by mosquito bites (West Nile transmitted between birds), blood transfusions, organ transplants or through placenta
