L15: Viral infections of nervous system

Question 1

Aseptic meningitis:

Answer 1

named due to failure to isolate the bacteria from the patient as its viral
Fever, HA, stiff neck. Mild disease

Question 2

Encephalitis:

Answer 2

more CNS symptoms and objective signs: seizures, visual disturbances, paralysis of extremities

Question 3

Poliovirus is a

Answer 3

Picornavirus, enterovirus

Question 4

poliovirus infection MOA

Answer 4

Multiplies in pharynx and small intestine→ viremia→ spreads to draining lymph nodes→ CNS: Anterior horns of cells of spinal cord and motor cortex (bulbar motor nuclei) of brain

Question 5

Classic polio presentation

Answer 5

asymmetric, flaccid paralysis of extremities

Question 6

Polio: Inapparent infection

Answer 6

Most common (90%) 
Asymptomatic to minor malaise

Question 7

Polio: Abortive illness

Answer 7

(4-8%)

Fever, malaise, drowsiness, N/V

Question 8

Polio: Nonparalytic poliomyelitis

Answer 8

(1-2%)

Fever, malaise, drowsiness, N/V, stiff neck, back

Question 9

Polio: paralytic myelitis

Answer 9

(<1%)

Lower motor neuron damage→ flaccid paralysis

Question 10

Post polio syndrome

Answer 10

Muscle weakness, pain, and fatigue 30-40 years after acute case of paralytic polio→ many patients today
Remaining motor units of CNS now react to overuse?

Question 11

antigenic types of polio virus

Answer 11

3

Question 12

Inactivated polio vaccine (IPV) (Salk)

Answer 12

Formalin inactivation of virus grown in monkey kidney culture

Question 13

Live polio vaccine (Sabin) (trivalent oral polio vaccine: OPV)

Answer 13

Live attenuated virus grown in primary monkey or human diploid cell cultures
→ Infects, multiplies, and immunizes recipient
→ Vaccine virus ends up in community→ can back mutate to the paralysis causing state: no longer in use in US due to risks

Question 14

Arboviruses come from

Answer 14

arthropods

Question 15

Arbovirus vectors

Answer 15

mosquitos, ticks required to complete life cycle

Question 16

Arbovirus animal reservoirs

Answer 16

birds, small mammals→ may no show overt disease

Question 17

Arbovirus dead end hosts

Answer 17

humans

Question 18

Arbovirus presentation is most commonly

Answer 18

Subclinical: most patients unaware of infection

Question 19

Overt arbovirus infection

Answer 19

abrupt onset of fever, HA, vertigo, photophobia, N/V, confusion, personality changes, focal/general seizures

Question 20

Overt arbovirus infection prognosis

Answer 20

complete recovery or long term deficits

Question 21

How to diagnose an arbovirus infection

Answer 21

“Diseases of specific place and time”

Diagnosis: age, location, time of year of infection, travel, vaccination history

Question 22

Prevention of arboviruses

Answer 22

Avoid infection

Interrupt chain of transmission

Avoid exposure: window screens, insect repellents

Immunize nonhuman amplifying hosts (if possible)

Question 23

Zika prevention

Answer 23

avoiding mosquitos, education
Usually travel-related infection
Delay pregnancy after infection

Question 24

West nile diagnosis

Answer 24

MAC-ELISA

IgM

Question 25

IgM MAC-ELISA for West Nile with show cross reactivity with

Answer 25

yellow fever, dengue, zika, St. Louis encephalitis, Japanese encephalitis viruses Yellow fever and japanese encephalitis→ long time for detectable reactive IgM

Question 26

serum sample MAC-ELISA of west nile will show

Answer 26

reveals recent infections and yellow fever vaccination

Question 27

CSF sample MAC-ELISA of west nile will show

Answer 27

IgM doesn’t cross blood brain barrier, (+) result is much more likely to reveal cause of encephalitis

Question 28

How to diagnose Zika

Answer 28

MAC ELISA | PCR

Question 29

IgM MAC-ELISA for Zika with show cross reactivity with

Answer 29

antigenic cross reaction with yellow fever, dengue, west nile

Question 30

Zika is spread by

Answer 30

mosquitos, possible STI

Question 31

Zika causes

Answer 31

birth defects if mother is infected | Guillain-Barre syndrome (GBS)

Question 32

West nile is

Answer 32

emerging, mosquito-borne infection in North America→ encephalitis

Question 33

Where is West Nile found?

Answer 33

Permanently established in US→ Repeated large scale outbreaks

Question 34

Togaviridae group

Answer 34

Ss (+) RNA, small (40 nm), enveloped | Subgroup: Alphaviruses

Question 35

Eastern Equine Encephalitis (EEE)

Answer 35

alphavirus

Question 36

Western Equine Encephalitis (WEE)

Answer 36

alphavirus

Question 37

Venezuelan Equine Encephalitis (VEE)

Answer 37

alphavirus

Question 38

Alphaviruses are

Answer 38

subgroup of togaviridae group

Question 39

St. Louis encephalitis

Answer 39

Flaviviridae group

Question 40

West Nile Virus

Answer 40

Flaviviridae group

Question 41

Dengue virus

Answer 41

Flaviviridae group

Question 42

Zika virus

Answer 42

Flaviviridae group

Question 43

3 subgroups of Arboviruses

Answer 43

1. Togaviridae group 2. Flaviviridae group 3. Bunyaviridae group

Question 44

California encephalitis virus (LaCrosse)

Answer 44

Bunyaviridae group

Question 45

Rabies morphology

Answer 45

Unique bullet shaped virion: ssRNA Envelope, matrix protein, glycoprotein, ribonucleoprotein

Question 46

rabies is found

Answer 46

Global distribution: rabies free areas: Australia, Antarctica, Great Britain

Question 47

Domestic dogs are a rabies reservoir in

Answer 47

Africa, South america, Asia, india

Question 48

Feral animals are a rabies reservoir in

Answer 48

Europe, Canada, USA

Question 49

USA rabies reservoirs

Answer 49

skunks, racoons, foxes, bats | → carnivores

Question 50

Bats and rabies

Answer 50

Bats: dangerous: minor scratches/wounds without a bite→ any contact→ prophylaxis

Question 51

How can rabies be transmitted

Answer 51

Bite: injection of saliva containing virus Contact: sufficient to pose a risk Aerosol transmission: has been documented→ bat caves

Question 52

Rabies incubation

Answer 52

Highly variable incubation period depends on distance of inoculation site from CNS: 2-16 weeks→ years

Question 53

Rabies prodrome phase

Answer 53

mild fever, pharyngitis, headache, coryza, abnormal pain/burning at site of inoculation, increased sensory sensitivity

Question 54

Rabies excitatory phase (furious phase in dogs)

Answer 54

anxiety, apprehension, hydrophobia in humans→ +/- death

Question 55

Rabies paralytic phase (dumb phase in dogs)

Answer 55

coma, hypotension, death

Question 56

Rabies diagnosis

Answer 56

History of bite/contact Skunk, fox, raccoon or bat exposure→ prophylaxis All animals considered rabid until proven otherwise by lab tests → kill and examine wild animals/stray pets→ Direct Fluorescent Antibody test (DFA) → viral inclusions: Negri body → quarantine healthy owned dogs and cats → rodents and rabbits rarely infected

Question 57

Negri body

Answer 57

viral inclusion of rabies seen on direct fluorescent antibody test

Question 58

Milwaukee protocol

Answer 58

2 cases of antiviral intervention success in cases of clinically overt rabies

Question 59

Usually clinical overt rabies

Answer 59

can't be treated

Question 60

After exposure to rabies

Answer 60

Post-exposure vaccination (prophylaxis)