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Flashcards in L84 Deck (34):
1

Define encephalitis

Inflam of BRAIN

2

Define meningo-encephalitis

Inflam meninges + brain

3

Define encephalo-myelitis

Inflam of brain + spinal cord

4

Encephalitis presenting symptoms

"Sleepy or acting weird"
Changes in consciousness
Changes in personality
Ataxia

5

Viral causes of encephalitis (usually not 1ary presentation - more likely a 2ary complication)

HSV
Other herpes viruses
Enteroviruses
Measles, mumps, JC

6

How does West Nile present?

1. 80% asymptomatic
2. AMS
Fever
Asymmetrical weakness w/ decreased reflexes of all extremities

7

West Nile virus family & genome

Flavi virus (Flavored corona)
+ssRNA
- Cytoplasmic replication
Icosahedral
Enveloped - buds out

8

West Nile vector vs resevoir

Mosquito = vector
Reservoir = birds

9

West Nile pathogenesis

Mosquito bites
Infects DCs at skin
Viremia = when get symptoms
CNS penetration + neuron invasion

10

What part of immune system controls West Nile?

Everything!
Need IFN + Ab + cell mediated

11

What genetic variant increases susceptibility to severe presentations of West Nile?

CCR5 delta 32
Butttt gives HIV resistance....
HIV resistance is better than the downsides of getting West Nile

12

What is the most common viral cause of encephalitis in the US?

West Nile
Esp summer & fall when mosquitoes are active

13

West Nile vaccine?

Nope

14

What is the "home grown West Nile"? Describe presentation.

St. Louis Encephalitis
Meningoencephalitis but without the paralysis of West Nile

15

What is the viral family of Eastern & Western Equine viruses? Therefore, describe genome.

Toga
+ssRNA - cytoplasmic replication
Icosahedral
Enveloped - buds

16

Describe the steps in which E&W Equine genome is transcribed.

+ssRNA parent
Make non-structural proteins
- Including RNA pol
RNA pol makes -ssRNA from +parent
-ssRNA codes for
1. +ssRNA for new viruses
2. mRNA --> codes for structural proteins

+ssRNA --> structural --> RNA pol & -ssRNA --> +ssRNA & mRNA --> structural proteins

17

Presentation of East Equine virus.

Acute: non-specific fever illness
2-3 days = encephalitis
If you progress to encephalitis, MUCH higher mortality w/ eastern

18

Presentation of West Equine virus.

Asymptomatic or mild fever illness
Small grp develop encephalitis
Low mortality

19

Equine resevoir vs vector

Horses + birds = reservoir
Transmitted by mosquitoes

20

Buzzword for Eastern vs Western

Eastern = USA swamps
Western = USA irrigation sites

21

What is the family and genome for La Crosse aka California viruses?

Bunya (Bring pol...)
-ssRNA - cytoplasm replication
*Brings own RNA pol*
Helical capsid
Enveloped

22

California virus presentation

Kids: neuroinvasive disease
I.e. seizures
Likely to recover w/o long term complications but scary in the short term
Least severe of all the mosquito borne encephalitis

23

How is California virus transmitted? Where?

Triseriatus mosquitoes
Live in hollowed out trees along forest edges
Midwest & south USA

24

Rabies - genome + family

Rhabdo
- ss RNA
Helical capsid
Enveloped

25

Rabies pathogenesis

Bite from rabid animal
Into muscle cells - SLOW replication - months
Eventually enters motor nerve
Retrograde
FAST replication - spreads throughout CNS
Peripheral dissemination

26

Once rabies gets to the CNS, what are the 2 types of damage that can occur - how does each determine symptomatic presentation?

1. Encephalopathic
Dysregulation of NT = excitatory state
Hyperactivity/agitated before...
2. Paralytic
Ascending flaccid paralysis
Neuron necrosis = coma

27

What might you see in muscle cells infected with rabies on histo?

Negri bodies = accumulation of M protein = matrix protein as virus replicates and buds out

28

Immune response to rabies

Abs vs G protein = attachment to muscle cells
Too slow - don't kick in until in CNS

29

What is the most common rabies host in the US vs worldwide?

US = feral cats
World = dogs
- Aka if someone in your clinic has rabies from a dog, they got it outside the US
Always be worried about bats, raccoons, etx

30

Symptoms of rabies

Numbness at bite site
Diplopia
N&V
CN palsy
Unsteady gait

31

Rabies incubation

LONG b/c localized
30-90 days

32

What's a weird symptoms that is a clue for rabies?

Fear of water
Suggests in encephalopathic stage of acute neuro disease

33

Test for rabies

CSR culture
DFA stain neck skin biopsy

34

Treat rabies

Gotta do it in the WINDOW period - when still localized in skin
2 parts:
+ rabies Ig
+ vaccine - must give IM in DELTOID