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Neurology > Viruses affecting the CNS > Flashcards

Viruses affecting the CNS Flashcards

1
Q

Acute viral meningitis generally is? Bacterial meningitis is?

A

Mild and self-resolving

Life-threatening

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2
Q

Which type of meningitis is more common, viral or bacterial?

A

Viral

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3
Q

What are indicators of bacterial meningitis?

A

CSF glucose < 34
CSF protein > 220
CSF WBC count > 2000
CSF neutrophil count > 1100

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4
Q

How many of the indicators need to be positive to rule in bacterial meningitis?

A

One –> >99% certainty

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5
Q

Presentation of viral meningitis?

A

Pts don’t typically appear extremely ill. -Present with Fever & malaise, Headache, Neck stiffness, Low back pain (typically overshadowed by HA)

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6
Q

Duration of viral meningitis?

A

Typically self-limiting over 10-14 days

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7
Q

Can viral meningitis be recurrent? If so, how?

A

Yes, persistent or latent infections (e.g. HSV)

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8
Q

Most common causes of viral meningitis?

A

Enterovirus [80%]

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9
Q

What did MMR vaccine help prevent?

A

Meningitis caused by Mumps [10%]

- Ask about vaccination Hx

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10
Q

Recurrent aseptic viral meningitis can be caused by? How is it prevented? Other causes?

A

HSV - 2, continuous tx with Acyclovir

HIV and VZV

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11
Q

Viral encephalitis?

A

Inflammation of the brain by direct virus infection of brain tissue

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12
Q

Causes of viral encephalitis?

A

Arbovirus [30%]
Enterovirus [23%]
HSV - 1 [27%]

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13
Q

How are arboviruses transmitted? Time of year?

A

Mosquitos or ticks

Spring and Summer

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14
Q

Which viral encephalitis is the most dangerous?

A

HSV - 1

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15
Q

Clinical course of viral encephalitis?

A 
Fever
HA
Lethargy
Prodromal URI
Confusion, seizures, coma, death
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16
Q

HSV Encephalitis can be caused by?

A

Acute infection or reactivation (more common)

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17
Q

Characteristic site of damage in HSV Encephalitis?

A

Temporal lobe

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18
Q

Genetic code of the flaviviruses?

A

Small, enveloped (+) strand RNA viruses

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19
Q

Examples of flaviviruses?

A

St. Louis and West Nile

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20
Q

Flavivirus replication cycle?

A
  1. Virus binds to membrane
  2. Enters by receptor-mediated endocytosis.
  3. Low pH dependent membrane fusion
  4. Uncoating from membrane
  5. (+) strand genome is translated into single
  6. Membrane-associated RNA replication (polyprotein cleaved)
  7. Virions morphogenesis in intracellular vesicles
  8. Virion transport glycoprotein maturation
  9. Vesicle fusion at plasma membrane –> virion release
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21
Q

Transmission of flavivirus?

A

By insect vectors

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22
Q

Where do flaviviruses initially replicate? What does it establish?

A

Site of inoculation

Transient primary viremia

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23
Q

Where do flaviviruses replicate post exposure as?

A

Macrophages, spleen, or lymph nodes

Note - it will most likely be cleared here as well

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24
Q

How does encephalitis occur in a flavivirus infection?

A

Infection is not controlled by immune system leading to a secondary viremia which results in severe systemic disease.

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25
Q

Where is St. Louis encephalitis virus epidemic?

A

North, Central, and South America

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26
Q

St. Louis Virus incubation period?

A

4 - 21 days

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27
Q

If pt dies from St. Louis virus, when is it most likely to occur?

A

W/n a week or two of presentation of CNS symptoms

28
Q

Typical symptoms of St. Louis virus infection? Do most progress beyond these symptoms?

A

Generalized malaise, fever, chills, headache, sore throat, and/or cough
No

29
Q

If secondary viremia occurs, how long before neurologic signs present?

A

1 - 4 days

30
Q

Are there vaccines available for St. Louis Virus? Antivirals?

A

None

None

31
Q

Where is the West Nile Virus enidemic?

A

Africa, West Asia, Europe, the Middle East, and the U.S.

32
Q

Reservoir of West Nile virus?

A

Birds

33
Q

For, West Nile virus are considered? How many of those infected will get severely iill?

A

Incidental host

1%

34
Q

Symptoms of West Nile virus?

A

Febrile, HA, sore throat, backache, myalgia, arthralgia, fatigue, Rash, lymphadenopathy, Acute aseptic meningitis or encephalitis

35
Q

Are there vaccines available for West Nile virus?

A

Nope

36
Q

Where is the Japanese encephalitis virus epidemic?

A

SE Asia and the Far East

37
Q

Is there a vaccine for Japanese encephalitis virus?

A

Yes - recommended for those traveling to rural areas of endemic areas

38
Q

Structure of togaviridae genome?

A

Small, eveloped, nonsegmented (+) strand RNA viruses

39
Q

Where is western equine encephalitis found? Eastern equine encephalitis? Venezuelan equine encephalitis?

A

West of the MS River
East of the MS River
Central and south America

40
Q

What group are western equine encephalitis, eastern equine encephalitis, and venezuelan equine encephalitis a part of?

A

Alphaviruses – togaviridae

41
Q

Typical disease progression of alphaviruses?

A

Fever for 7 to 11 days followed by resolution or abrupt onset of encephalitis –> Vomiting, dizziness, confusion, increasing loss of consciousness and w/n 2-3 days patients become comatose and die

42
Q

Where does alphavirus transmission cycle occur?

A

Swampy areas

43
Q

Structure of bunyaviruses genome?

A

Enveloped, segmented, single-stranded (-) sense RNA virus

44
Q

How are bunyaviruses transmitted?

A

Mosquitoes

45
Q

The most common cause of arboviral-induced pediatric encephalitis in the U.S.?

A

La Crosse Virus

46
Q

What is special about the replication strategy of bunyaviruses?

A

Genes are found on 2 - 3 separate RNA segments

47
Q

Structure of Rhabdoviridae genome?

A

Enveloped, nonsegmented (-) strand RNA virus

–> Characteristic bullet-shaped morphology

48
Q

How do rhabdoviruses enter the cell?

A

pH-dependent manner following endocytosis

49
Q

Glycoprotein found in rhabdoviruses? Function?

A

G

Attachment and fusion (pH-dependent)

50
Q

Are rhabdoviruses syncytia forming?

A

No

51
Q

What is the speed in which rabies virus reacts?

A

Slow, progressive disease

52
Q

Rabies is uniformly fatal if what fails to occur?

A

Postexposure treatment is not administered

53
Q

How does transmission of rabies virus typically occur? How else might it occur?

A

Animal bite; Nonbite exposure can occur (scratches, licks, aerosols)

54
Q

Incubation period of rabies virus?

A

2 - 3 months

55
Q

How long is the prodromal period in rabies?

A

2 - 10 days following exposure

Includes malaise, fever, headache

56
Q

When does the acute neuologic phase occur in rabies?

A

Months to years after initial exposure

57
Q

What happens during the acute neurologic phase of rabies?

A

Nervous system dysfunction

58
Q

Types of nervous system dysfunction seen in rabies? Describe them

A 
Furious rabies
 - anxiety, agitation
 - Encephalitis predominates
 - common symptom is hydrophobia
Dumb rabies
 - paralysis
59
Q

What follows the acute neurologic phase in rabies infections?

A

Coma and death

  • 2 - 7 days after acute neurologic phase
  • can last 3 day - ~1 month
60
Q

Is there a vaccine for rabies?

A

Yes - three and all are inactivated

61
Q

How do you treat rabies?

A

Post-exposure prophylaxis

Inject the vaccine in wound site after thorough cleaning

62
Q

Structure of lymphocytic choriomeningitis virus (LCMV) [an arenavirus]?

A

Enveloped, segmented, ambisense RNA virus

63
Q

LCMV virions contain how many RNA segments? They encode for how many proteins?

A

2

4

64
Q

How does LCMV enter the cell?

A

pH-dependent endocytosis

65
Q

How does replication occur in an arenavirus? Describe it

A

ambisense strategy

  1. The genome is first used as a template for transcription and the NP and L mRNAs are produced from either the L (long) or S (short) RNA segment
  2. The polymerase then produces a full-length antigenome for each of the segments
  3. The “(+)”-sense antigenome is then used as a template for transcription of the glycoprotein mRNA
  4. Virus particles are then assembled and released from the cell surface by budding
66
Q

How is arenavirus transmitted?

A

Inhalation of aerosolized rodent excreta and saliva

67
Q

How is LCMV disease characterized?

A

Two phases

  • Prodrome of fever, HA, nausea, and vomiting
  • Aseptic meningitis ~ 10 days later

Neurology (25 decks)

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