Viral Encephalitis

Question 1

What is the definition of encephalitis?

Answer 1

Inflammation of brain

Question 2

What is the definition of meningoencephalitis?

Answer 2

Inflammation of brain and meninges

Question 3

What is the definition of encephalomyelitis?

Answer 3

Inflammation of brain and spinal cord

Question 4

What are symptoms/signs of encephalitis?

Answer 4

Depressed or altered level of consciousness, changes in personality or ataxia
PLUS
One or more of the following:
- Fever
- Seizures
- Focal neurological deficits
- CSF pleocytosis

Question 5

What are major viral causes of encephalitis?

Answer 5

Enteroviruses, HSV, other herpes viruses

Question 6

What family is West Nile Virus in?

Answer 6

Flaviviridae

Question 7

What are characteristics of genome/structure of Flaviviridae?

Answer 7

ss (+) RNA
pH dependent uncoating
Replicates in cytoplasm
Virus assembles at ER/Golgi

Question 8

How is West Nile virus transmitted?

Answer 8

Mosquito (Culex)

Rarely blood transfusion, or verticl

Question 9

What cytokine may help facilitate neuroinvasion with West Nile virus?

Answer 9

TNFalpha

Question 10

What is clinical presentation of West Nile virus?

Answer 10

80% asymptomatic
20% non-secific febrile illness
~1% neuroinvasive disease (encephalitis or encephalomyelitis)

Question 11

What is the reservoir for West Nile?

Answer 11

Birds

Question 12

In what population is there highest incidence of neuroinvasive disease and highest mortality due to WNV?

Answer 12

elderly

Question 13

What is a flavivirus very similar to WNV?

Answer 13

St. Louis Encephalitis virus

Question 14

What family does Eastern and Western Equine encephalitis viruses fall in?

Answer 14

Togaviridae

Question 15

What are characteristics of genome/structure of Togaviridae?

Answer 15

Nonsegmented

(+) ss RNA

Question 16

What is clinical presentation of EEEV?

Answer 16

Abrupt onset shills, fever, malaise, arthralgia, myalgia
Encephalitis develops later
Higher mortality in encephalitis patients

Question 17

What is clinical presentaiton of WEEV?

Answer 17

Asymptomatic or mild systemic illness with fever, malaise, myalgia
Small number develop encephalitis later
Lower mortality in encephalitis patients

Question 18

What family does La Crosse (california) virus fall in?

Answer 18

Bunyaviridae

Question 19

What are characteristics of genome/structure of Bunyaviridae?

Answer 19

Enveloped 
Segmented
(-) ssRNA
Replicates in Cyoplasm
Assembles at Golgi

Question 20

What are clinical manifestations of La crosse virus?

Answer 20

Fever, headache, nausea, vomiting, fatigue, lethargy
Neuroinvasive (encephalitis) more common in children
Seizures common
Low mortality

Question 21

What transmits La crosse virus?

Answer 21

Mosquito from small mammals (chipmunks, squirrels)

Question 22

What family does Rabies virus fall in?

Answer 22

Rhabdoviridae

Question 23

What are characteristics of genome/structure of Rhabdoviridae?

Answer 23

Enveloped
(-) ss RNA
Bullet-shaped

Question 24

What is the pathogenesis of Rabies?

Answer 24

Enters muscle cells, replicates slowly
Enters motor nerve, travels rapidly via retrograde transport to spinal cord
Virus spreads rapidly through spinal cord and brain
Virus disseminates via PNS throughout body including skin, salivary glands, heart

Question 25

What is the histopathological hallmark of Rabies?

Answer 25

Negri bodies in neurons

Question 26

If you generate effective neutralizing antibodies to Rabies, why are they not protective?

Answer 26

Antibody response doesn't begin until after infection of CNS | Too little too late

Question 27

What animal do most cases of rabies come from worldwide?

Answer 27

Dogs

Question 28

What animal do most cases of rabies come from in US?

Answer 28

Bats

Question 29

What are clinical manifestations of rabies?

Answer 29

Incubation period - symptom free Prodrome and early symptoms: fever, malaise, pain, or paresthesia at bite site Acute neurologic disease Death

Question 30

What symptoms are included in the acute neurologic disease caused by rabies?

Answer 30

Agitation, delerium, hallucinations, bizarre behavior, *hydrophobia* Autonomic dysfunction: tachy-bradycardia, hyper-hypotension, excessive salivation and sweating, pupillary dilation Muscle spasms, myoclonus, seizures

Question 31

How is rabies diagnosed?

Answer 31

Direct flourescent antibody from skin biopsy | PCR

Question 32

What is treatment for rabies?

Answer 32

Wound care Call public health authorities Passive immunization with rabies immunoglobulin Active immunization with series of IM rabies vaccine injections