(32) Viruses Affecting the CNS

Question 1

What levels for the following labs suggest bacterial etiology of meningitis?
CSF glc
CSF protein
CSF WBC
CSF neutrophil

Answer 1

CSF glc < 34
CSF protein > 220
CSF WBC > 2000
CSF neutrophil > 1180

only need 1 of the above to make Dx

Question 2

presentation of viral meningitis

Answer 2

fever, malaise, neck stiffness, low back pain

Question 3

etiologies of viral meningitis

Answer 3

80% from enterovirus (Echo, Coxsackie, enterovirus 71)

10% from Mumps (prior to MMR vaccine)

Question 4

recurrent aseptic meningitis is due to

Answer 4

HSV-2 (genital herpes)

Question 5

HIV and VZV cause ______ meningitis

Answer 5

recurrent

Question 6

What are the 3 etiologies of viral encephalitis

Answer 6

arbovirus (West Nile, St louis, La Crosse)
enterovirus
HSV-1

Question 7

clinical course of viral enchephalitis

Answer 7

preodromal URT infection 
fever
headache
letharghy
parenchymal involvement = seizures, coma, death

Question 8

what is the treatment for HSV-1 encephalitis

Answer 8

acyclovir

Question 9

what is the treatment for CMV encephalitis

Answer 9

gancyclovir

Question 10

HSV encephalitis is more common in (acute, reactivation, or latent) infection

Answer 10

reactivation of latent

Question 11

Where in the brain does HSV encephalitis characteristically cause damage

Answer 11

temporal lobe (due to necrosis)

Question 12

What are the mosquito borne encephalitis viruses?

Answer 12

Flaviviruses = west nile and st. louis

alphaviruses = eastern, western, and venezuelean equine

bunyavirus = California encephalitis, la crosse virus

Question 13

What are the animal transmitted encephalitis viruses?

Answer 13

rhabdovirus (rabies) and arenavirus (LCMV = lymphocytic choriomengingitis virus)

Question 14

structures of flavivirus (West nile and St. louis)

Answer 14

enveloped + RNA

Question 15

describe the replication cycle of the flavivirus

Answer 15

enter via receptor mediated endocytosis. low pH allows membrane fusion and then uncoating. + strand translated into Rdrp. + strand is used to make - strand which is then used to make progeny. virion assembly and budding

Question 16

all flaviviruses are transmitted by ____

Answer 16

insect vectors

Question 17

what are flaviviruses that cause dz in US

Answer 17

west nile, st louis, yellow fever, dengue (usually traveled abroad)

Question 18

length of incubation prd for SLE

Answer 18

4 - 21 days

Question 19

how long after URT/primary viremia will neurological symptoms of SLE present

Answer 19

1-4 days

Question 20

describe the transmission cycle of the west nile virus

Answer 20

bird reservoir and mosquito vector to infect humans

Question 21

distinguishing characteristic/presenting signs and symptoms of west nile infection

Answer 21

rash and lymphadenopathy

Question 22

most significant etiology of arboviral encephalitis

Answer 22

Japanese encephalitis virus

Question 23

structure of togavirus (alphavirus)

Answer 23

enveloped, non-segmented + RNA

Question 24

vector for alphaviruses

Answer 24

mosquito

Question 25

what determines the severity of the dz in alphavirus infections?

Answer 25

dept on dose and age of pt

Question 26

describe the typical dz progression of an alphavirus infection

Answer 26

fever for 7 to 11 days then resolution of abrupt onset of encephalitis with vomitting, dizzynes, confusion. 2-3 days and person becomes comatose and dies

Question 27

describe the structure of the bunyaviruses

Answer 27

enveloped, ss - RNA

Question 28

what is the most common cause of arboviral induced pediatric encephalitis in US

Answer 28

La crosse virus

Question 29

structure of rabies virus

Answer 29

enveloped, nonsegmented - RNA

bullet shaped morphology

Question 30

describe the replication cycle of rhabdoviridae

Answer 30

endocytosed and used glycoprotein to attach at fuse (pH dept process) Rdrp is packaged in virion with - RNA so when uncoated a + RNA is made. This RNA serves as the template for the progeny -RNA and the code for the RDRP to be made to be packaged with the - RNA

Question 31

Why does rabies virus characteristically involve the CNS

Answer 31

the attatchement glycoprotein shows neurotrophism

Question 32

during the final stages of rabies, high conc of virus can be found in what organ

Answer 32

salivary glands

Question 33

how is rabies transmitted

Answer 33

animal bite, sratch, lick

Question 34

what is the incubation period for rabies

Answer 34

usually 2-3 mos (BUT can be as short as 1 week)

Question 35

what determines the incubation period for rabies

Answer 35

proximity of bite to CNS

Question 36

Describe the progression of the dz caused by rabies

Answer 36

1. prodromal = 2-10 days after exposure in which pts has fever, malase, and headache
2. neurologic phase = mos to years after exposure in which the pt gets anxiety, agitation (when enchephalitis develops), paralysis
3. coma and death 2-7 days after acute neuro phase and can last 3 days to ~ 1 month

Question 37

treatment after bite from rabies infected animal

Answer 37

2qw wound and admin human anti-rabies Ig to wound and admin rabies vacine IM on days 0, 3, 7, 14, 28

Question 38

what type of vaccine is rabies virus

Answer 38

inactivated

Question 39

describe the structure of LCMV

Answer 39

enveloped, segmented, ambisense RNA (2 segements)

Question 40

describe the replication scheme of LCMV

Answer 40

endocytosed

NP portion of S strand is replicated first then GP then L portion of L strand

?????

Question 41

how is arena virus transmitted`

Answer 41

inhalation of aerosolized rodent excreta and saliva

Question 42

describe the phases of LCMV/arenavirus dz progression

Answer 42

prodrome of fever headache, N/V. 10 days later get aseptic meningitis (rarely fatal)