2: Common Viral syndromes/ Rabies

Question 1

what is a quick way to know if a virus has DNA or RNA?

Answer 1

if it causes cancer - DNA, b/c incorporate it into genome, which causes the growth dysregulation
-one exception: Hep C

Question 2

describe the virus that causes polio

Answer 2

picornavirus

• nonenveloped
• RNA
• enterovirus
• infects oropharynx tissues

Question 3

why does polio have a longer incubation period?

Answer 3

infects oropharynx, then secreted into saliva and swallowed, then multiples in intestinal mucosa and lymph nodes

Question 4

how often does polio get into the CNS and what does it cause?

Answer 4

1% invades CNS to replicate in motor neurons of spinal cord or brain stem - paralysis

Question 5

what are the cellular receptors used by polioviruses?

Answer 5

members of Ig superfamily (chromosome 19)

Question 6

what do Ig superfamily members bind to?

Answer 6

integrins

Question 7

what do selectins bind to?

Answer 7

surface carbohydrates

Question 8

polio vaccines?

Answer 8

Salk- inactive polio virus injection

• requires booster
• no risk of paralytic disease

Sabin (oral) - attenuated polio virus

• risk of paralytic disease, esp in immunocompromised
• greater duration of immunity
• induction of IgA production in GI tract
• “free immunization” by virus shed in stool

Question 9

common viral syndromes of URT

Answer 9

• adenovirus
• rhinovirus
• echovirus
• coronavirus

Question 10

common viral syndromes of LRT

Answer 10

• influenza
• parainfluenza
• RSV

Question 11

common viral syndromes of GI tract/liver

Answer 11

• rotavirus (kids)
• Norovirus (cruises)
• hepatitis A,E

Question 12

what is the cause of more than 50% of common colds?

Answer 12

rhinovirus

Question 13

what does rhinovirus bind to?

Answer 13

ICAM-1

Question 14

pathogenesis of rhinovirus

Answer 14

• slight damage

- hypersecretion due to bradykinins and inflammatory response

Question 15

second most common cause of common cold?

Answer 15

coronavirus

Question 16

symptoms of coronavirus

Answer 16

• profuse nasal discharge

- little effect on LRT

Question 17

function of hemagglutinin

Answer 17

binds to sialic acid-containing proteins and lipids on most cells and mediates entry into cell

Question 18

function of neuraminidase

Answer 18

may play a role in releasing virus from host cells (cleaves sialic acid)

Question 19

A,B, or C: which causes pandemics/epidemics of flu? what do the others do?

Answer 19

A

others infect mostly kids

Question 20

what syndrome is this associated with in kids and with what medicine?

Answer 20

aspirin in kids for flu -> Reye’s syndrome

Question 21

most common cause of myocarditis

Answer 21

coxsackie

Question 22

pathology of flu

Answer 22

• mucosal hyperemia with lymphomonocytic and plasmacytic infiltration of submucosa
• hypersecretion
• obstruction due to secretions results in secondary bacterial infections - most deaths from secondary bacterial pneumonias

Question 23

antigenic drift vs. antigenic shift

Answer 23

drift: mutations year to year

shift: cause of major epidemics - introduction of new isotype/subtype of virus by recombination of two different flu viruses or 2 different viruses, particularly a human + an animal virus
- shift must involve change in HA, may/may not involve NA

Question 24

what is croup and what causes it?

Answer 24

acute laryngotracheobronchitis

• parainfluenza type 3
• acute febrile illness w/ inspiratory stridor, hoarseness, and barking cough

Question 25

most common cause of viral pneumonia in children less than 2 y/o

Answer 25

RSV

Question 26

common cause of death in infants aged 1-6 mo

Answer 26

RSV

Question 27

what accounts for most forms of pneumonia and bronchiolitis (croup) in children

Answer 27

RSV

Question 28

typical presentation of RSV

Answer 28

severe pneumonia in infants: - infant w/ history of fever, cough, poor feeding - appears ill - high RR - XR w/ patchy bilateral infiltrates

Question 29

common cause of acute respiratory disease and pneumonia in military recruits

Answer 29

adenovirus

Question 30

what will histology of adenovirus show?

Answer 30

cowdry type A intranuclear inclusions

Question 31

pathology of adenovirus

Answer 31

epithelial necrosis with sloughing

Question 32

what three bugs can cause pneumonias in immunosuppressed people?

Answer 32

- CMV - varicella - HSV

Question 33

two fecal/oral viruses that don't cause GI disease

Answer 33

enteroviruses - coxsackie, poliovirus

Question 34

major cause of diarrhea in infants

Answer 34

rotavirus - most common at time of weaning (IgA in mother's milk protective)

Question 35

pathology of rotavirus

Answer 35

destroy mature host epithelial cells

Question 36

what does norwalk agent cause

Answer 36

epidemic viral gastroenteritis

Question 37

name some GI viruses

Answer 37

coronavirus can cause diarrhea enteric adenoviruses Hep A, E

Question 38

transmission of rabies

Answer 38

contamination of open wounds or mucous membranes by saliva from infected animals

Question 39

what animals account for most cases of animal rabies in US

Answer 39

raccoons foxes skunks

Question 40

in US, how are most humans infected

Answer 40

bats or cats who have been infected by bats

Question 41

pathogenesis of rabies

Answer 41

- virus excreted in saliva of infected animal - saliva contaminates bite wound - virus replicates, travels through axons to CNS (weeks) - establishes infection in brain - virus travels through nerves to salivary glands - in salivary gland, virus excreted in saliva

Question 42

symptoms of rabies

Answer 42

- hydrophobia | - CNS sx

Question 43

histology of rabies

Answer 43

Negri bodies in purkinje cell bodies

Question 44

what is the only way rabies can be diagnosed?

Answer 44

direct examination of brain tissue from animal

Question 45

pre-exposure prophylaxis for rabies

Answer 45

vaccination series of 3 injections + boosters if bitten

Question 46

post-exposure prophylaxis for rabies

Answer 46

- check animals for rabies (kill or quarantine) - if no animal, then vaccinate - vaccination series, 5 injections - rabies-specific gamma globulin