02c: Influenza

Question 1

(X) family of (bac/viruses) cause influenza. Transmission is via:

Answer 1

X = orthomyxoviridae
Viruses;

Resp secretions, small particle aerosols

Question 2

Orthomyxoviridae family of viruses: (env/non-env) with (RNA/DNA). What’s unique about their genetic info?

Answer 2

Env;
ssRNA (neg-sense);

Composed of 8 separate segments

Question 3

Orthomyxoviridae: glycoprotein spikes form part of (X). What are the types of spikes and respective functions?

Answer 3

X = envelope;

1. Hemagglutinin (attachment)
2. Neuraminidase (release)

Question 4

Influenza types (A/B/C/D) generally only infect humans.

Answer 4

B and C

Question 5

Influenza A can be further divided into subtypes based on (X). Which of these are most important in humans?

Answer 5

HA (hemagglutinin) and NA (neuraminidase) glycoproteins

H1, H2, H3;
N1, N2

Question 6

Influenza virus: (X) are proteins that determine the Influenza Type (A-D).

Answer 6

X = M1 matrix protein and Nucleoprotein

Question 7

Ab against (X) neutralizes influenza virus infectivity and is major determinant of immunity.

Answer 7

X = HA (hemagglutinin)

Question 8

Ab against (X) limits influenza virus replication (and severity of illness), but doesn’t prevent infection.

Answer 8

X = NA (neuraminidase)

Question 9

T/F: Infection by one subtype of Influenza virus doesn’t provide cross-protection against another.

Answer 9

True

Question 10

Antigenic (shift/drift): small changes that occur frequently within influenza (A/B/C/D). These changes are a result of (X).

Answer 10

Drift;
A or B
X = point mutation (accumulation) in RNA segment that codes for HA

Question 11

Antigenic (shift/drift): appearance of influenza (A/B/C/D) virus with brand new (X).

Answer 11

Shift;
A;
X = HA (plus/minus new NA)

Question 12

Reappearance of influenza A virus after decades of absence is example of antigenic (shift/drift). Is this capable of causing pandemic disease?

Answer 12

Shift;

Yes

Question 13

(Pandemic/Epidemic) outbreak of influenza is confined to one location, generally during (X) season.

Answer 13

Epidemic;

X = winter

Question 14

Characteristic pattern seen in (pandemic/epidemic) influenza A outbreaks: begins abruptly in (adults/children/elderly), peaks over (X) time period and lasts for (Y) time period.

Answer 14

Epidemic;
Children (acute febrile rep illness)
X = 2-3 week
Y = 2-3 month

Question 15

T/F: Increase in abseneeism from work/school is early manifestation (an indication) of epidemic flu outbreak.

Answer 15

False - late manifestation

Question 16

Epidemic outbreaks have attack rates (in general population) of (X)%. And pandemics?

Answer 16

X = 10-20

Pandemics: exceed 50%

Question 17

(Pandemic/Epidemic) outbreak of influenza involves emergence of new virus (to which population has no immunity). Thus, local (X) progress to involve all parts of world simultaneously.

Answer 17

Pandemic;

X = epidemics

Question 18

Average influenza incubation period:

Answer 18

2 days (range: 1-4 days)

Question 19

Influenza virus: spreads to (X) tissue layer and targets/destroys (Y) cells. This results in the characteristic (Z) symptoms.

Answer 19

X = Respiratory tract epithelium
Y = ciliated epithelial
Z = respiratory

Question 20

T/F: Quantity of influenza virus is proportional to the severity of symptoms in patient.

Answer 20

True

Question 21

How might influenza virus infection lead to systemic symptoms?

Answer 21

Proinflammatory cytokine release in blood

Question 22

T/F: Influenza viral shedding occurs for 2 weeks in adults and children.

Answer 22

False - age-dependent (3-5 days in adults)

Question 23

T/F: Immunity to influenza virus is type-specific.

Answer 23

False - subtype-specific

Question 24

What’s the most important (early) clinical finding in influenza infection?

Answer 24

Fever rises to 101-104oF (38-40oC) within 12 hours

Question 25

Influenza: when (in clinical course) do respiratory symptoms become apparent?

Answer 25

Once systemic symptoms diminish (fever lasts about 1-5 days)

Question 26

Which patient populations are more susceptible to frequent and severe flu illness?

Answer 26

1. Elderly (over 60) 2. Smokers 3. Pregnant women in trimester 2-3 4. HIV pts

Question 27

Attack rates and higher max temperatures from flu infection may be seen in which patient population?

Answer 27

Kids

Question 28

Increased frequency of GI symptoms (N/V, abd pain) from flu infection may be seen in which patient population?

Answer 28

Kids

Question 29

List the respiratory complications that can occur as result of flu infection.

Answer 29

1. Primary flu virus pneumonia 2. Secondary bac pneumonia 3. Mixed bac and viral pneumonia 4. Abnormal tracheobronchiolar clearance, airway hyperactivity/dysfunction

Question 30

List some non-respiratory complications that can occur with influenza virus infection.

Answer 30

1. Myositis and rhabdomyolysis 2. Myocarditis and pericarditis 3. Aseptic meningitis and encephalitis

Question 31

Definitive diagnosis of influenza virus infection is by:

Answer 31

Isolate from throat/nasal cavity and culture, PCR, or immunofluorescence testing

Question 32

List the viruses that might be on your differential for influenza infection.

Answer 32

Parainfluenza, Adenovirus, RSV, and Enterovirus

Question 33

Influenza virus vaccine is (live/dead).

Answer 33

Both exist; | live vaccine only for healthy individuals over 2 y.o.

Question 34

Killed influenza virus vaccine: formulation is based on (X) strains.

Answer 34

X = prior season's

Question 35

T/F: Killed virus vaccine, when matched correctly to epidemic strain, has max 50% efficacy.

Answer 35

False; 60-90%

Question 36

T/F: All people over 50 should be vaccinated for flu with killed virus vaccine.

Answer 36

True

Question 37

T/F: All kids under age 5 should be vaccinated for flu with killed virus vaccine.

Answer 37

False - not if under 6 mo old

Question 38

In elderly, flu vaccination is (X)% effective in preventing hospitalization and pneumonia.

Answer 38

X = 50-60

Question 39

T/F: Side effects of flu vaccine can include fever, systemic symptoms, and reaction at site.

Answer 39

True

Question 40

Killed flu vaccine is contraindicated for which population(s)?

Answer 40

Those with anaphylactic hypersensitivity to eggs

Question 41

List the rare complications that can occur following killed flu vaccine injection.

Answer 41

Guillain-Barré syndrome

Question 42

List the components that are included in formal nomenclature of influenza virus.

Answer 42

1. Type 2. Infected animal 3. Geographic site of isolation 4. Strain number 5. Year of isolation 6. Subtype

Question 43

We need new flu vaccines every year due to antigenic (shift/drift).

Answer 43

Drift

Question 44

Worst case scenario of flu pandemic would mimic that of (X) flu in (Y) year.

Answer 44

``` X = Spanish Y = 1918 ``` Highly contagious and deadly (killed more americans than all the wars of 20th century!!)

Question 45

Spanish flu mortality rate was (X)%, unlike other flu epidemics that had (Y)% mortality rate.

Answer 45

``` X = 2.5 Y = under 0.1 ```

Question 46

Antiviral drugs must be taken consistently in (X) patient populations to prevent flu infection.

Answer 46

X = immunosuppressed or those allergic to vaccine