CNS Infections- Viral – Flashcards

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Name 3 ways in which viruses cross the blood brain barrier:
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Growing across it
Being passively transported across it in intracellular vacuoles
Being carried across by WBCs
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What is the receptor for measles?
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CD46
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What is the receptor for polio?
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CD155PVR
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What is the receptor for HSV?
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Heparin sulfate, TNF receptor
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What is the receptor for rabies?
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AChR, NCAM
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What is the receptor for HIV?
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CD4+CCR5 or CXCR4
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What is hematogenous entry and what two types of viruses can do this?
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Directly into blood stream
Arboviruses- mosquito injection
Rabies- from a bite
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What is neural entry into the CNS, and what viruses do this?
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Spread from distal neural structures to CNS-
Rabies, HSV, VZV
Travel up ganglia
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What are the symptoms of frontal lobe abscess?
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Frontal sinusitis
Headache
Memory defects
Attention loss
Diminished intelligence
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What are the symptoms of temporal lobe encephalitis?
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Personality changes, visual field defects, hemiparesis (with large lesion), focal seizures
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What are the symptoms of basilar meningitis?
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Headache- suboccipital
Neck stiffness
Diplopia
Cranial Nerve palsy
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What are 3 important aspects of the immune response to CNS pathogens?
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-inflammation->edema->tissue death
-decreased capillary perfusion to brain
-neurological symptoms
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What is the main class of enteroviruses, and how are they spread?
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Picornaviridae- SMALL RNA VIRUSES- fecal-oral transmission without symptoms of diarrhea
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What changes do we see in CSF in bacterial infection?
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Highly elevated PMNs
Protein above 100
Glucose less than 45
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What changes do we see in CSF in viral infection?
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Presence of lymphocytes/monocytes
Protein 50-100
Normal Glucose (Esper said differently)
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What are the classic symptoms of viral meningitis?
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Fever, nuchal rigidity, photophobia, headache
-irritability, nausea/vomiting, rash, weakness x 18-36 hours
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How long does viral meningitis usually take to clear?
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Self limiting withing 7-10 days
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What virus causes Hand Foot and Mouth disease?
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Coxsackie A
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What virus causes viral myocarditis?
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Coxsackie B
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What class of virus is polio? Describe it?
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Enterovirus
+ stranded RNA, non-enveloped
Spread fecal-oral
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What viruses are estimated to cause >85% of all meningitisWhen are we more likely to see these cases?
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Non-polio enteroviruses
Warmer months
Think coxsackie A and B
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What are some symptoms associated with enterovirus meningitis (besides the main meningitis symptoms)?
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Pharyngitis, pleurodyna (pain in pleura), rash, pericarditis
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Describe Arboviruses generally and what they cause:
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Postive stranded enveloped RNA viruses
Mosquito vector borne
Cause ENCEPHALITIS (and sometimes meningitis)
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What is the most common arbovirus in the US?
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Saint Louis Encephalitis (SLE)
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What is the most common arbovirus worldwide?
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Japanese B
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What is the most common clinical manifestation of arbovirus infection?
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Meningoencephalitis instead of pure aseptic meningitis
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Why are seizures more common in arbovirus infection?
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Because they cause encephalitis too
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Describe mumps and its most important permanent effect:
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Mumps- negative stranded RNA virus- helical- ENVELOPED
Meningitis is a common complication
Causes Bilateral Parotitis (chipmunk cheeks)
CAN CAUSE STERILITY IN MALES (orchitis)
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What virus is the leading cause of encephalitis?
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HSV-1
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Which herpes is responsible for genital infections and neonatal meningitis?
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HSV-2
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Describe the structure of herpes viridae:
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DNA virus; Icosahedral; ENVELOPED
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When is VZV CNS infection most common?
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Zoster REACTIVATION
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What drug should be given immediately upon suspicion of herpes viral infection?
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Acyclovir IV
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What are two ways in which viral encephalitis can be prevented?
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Mosquito eradication
Sanitation
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Your patient presents with obvious infectious lesions of the temporal lobes and obvious visible vesicular outbreak on their face. What is your best guess for the causative agent?
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HSV
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Your patient presents with a rash and encephalitis. You notice the rash covers a distinctive/definable region. What is your best guess for the causative agent?
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VZV- shingles
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Your patient presents with a bite and neurological symptoms. What is your best guess for a causative agent?
You slay the offending animal and look at its brains. What do you find?
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Rabies
NEGRI BODIES
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When is a patient most likely to acquire herpes encephalitis?
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On REACTIVATION of HSV-1
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Where does HSV-1 reactivate and where does it infect?
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Usually reactivation in the trigeminal ganglia
Infects temporal lobe
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What characterizes an "intermediate" host?
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Lower viral titers, difficult to spread
A "dead end" for the virus
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Where on earth would you find arboviruses in their highest titre form(tricky question)
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Mosquito salivary glands
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What aspect of a patient history is super important in cases of encephalitis?
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Travel history
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Describe the structure of the rabies virus:
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Negative stranded RNA virus
HELICAL, ENVELOPED
BULLET SHAPED
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What does rabies cause?
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Acute, progressive, incurable and DEADLY encephalitis
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What 4 animals most commonly transmit rabies in the US? Worldwide?
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Racoons, bats, foxes, skunks

Worldwide= dogs
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How long is the incubation period for rabies?
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1-3 months
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How does rabies travel in the CNS?
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RETROGRADE TRANSPORT
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Describe the path of travel of the rabies virus in an infected person:
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From the brain, the virus returns to the periphery, to the salivary glands (which are highly innervated)
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What are the symptoms of rabies?
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Fever, chills, headache, difficulty swallowing, HYDROPHOBIA
Hallucination, disorientation, paralysis, coma, death
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Describe the prodrome of rabies:
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Flu-like
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How does rabies eventually kill the patient?
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Cardiac or respiratory arrest
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How is rabies diagnosed?
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Perivascular cuffing
Skin biopsy, corneal impression, brain biopsy with PCR/IF
NEGRI BODIES
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How is rabies treated?
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Clean the wound, VACCINATION (only time we vaccinate after exposure)
Half in the wound, half IM
Confirm if animal is rabid
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Describe the structure of HIV:
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Positive stranded RNA RETROVIRUS
Enveloped
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Describe the course of HIV encephalitis
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Invades CNS shortly after initial infection- pleocytosis in CSF, mild meningitis like illness
Later subacute encephalitis with dementia
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Describe the pathology of HIV related dementia:
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Brain shrunken with enlarged ventricles
Vacuolization of myelin tracts
Virus infects the macrophages (microglia) in the CNS
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What does mumps encephalitis usually follow?
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Parotitis (7-10 days)
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What virus causes subacute sclerosing pan encephalitis (SSPE)?
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Measles
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What characterizes the pathology of subacute sclerosing pan encephalitis?
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Progressive neurological deterioration due to brain inflammation and nerve cell death
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What are some symptoms of SSPE?
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Behavior changes, intellect/memory issues, movement issues, gait problems, seizures, speech difficulty, dysphagia
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What causes myelitis?
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POLIO- replication in neurons of gray matter of brain and spinal cord
FLACCID PARALYSIS without sensory loss
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What is affected in bulbar polio?
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Respiratory muscles, medulla oblongata
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What are the two types of polio vaccine and which can revert to virulent strain?
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Salk- Killed
Sabin- Live- can revert
Not used in US anymore
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What viruses that cause encephalitis can be revealed by a Tzanck test?
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Herpes, VZV
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What virus causes Progressive Multifocal Leukoencephalopathy, and in what patient population?
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JC Virus- immunocompromised patients
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