02c: Influenza Flashcards
(X) family of (bac/viruses) cause influenza. Transmission is via:
X = orthomyxoviridae
Viruses;
Resp secretions, small particle aerosols
Orthomyxoviridae family of viruses: (env/non-env) with (RNA/DNA). What’s unique about their genetic info?
Env;
ssRNA (neg-sense);
Composed of 8 separate segments
Orthomyxoviridae: glycoprotein spikes form part of (X). What are the types of spikes and respective functions?
X = envelope;
- Hemagglutinin (attachment)
- Neuraminidase (release)
Influenza types (A/B/C/D) generally only infect humans.
B and C
Influenza A can be further divided into subtypes based on (X). Which of these are most important in humans?
HA (hemagglutinin) and NA (neuraminidase) glycoproteins
H1, H2, H3;
N1, N2
Influenza virus: (X) are proteins that determine the Influenza Type (A-D).
X = M1 matrix protein and Nucleoprotein
Ab against (X) neutralizes influenza virus infectivity and is major determinant of immunity.
X = HA (hemagglutinin)
Ab against (X) limits influenza virus replication (and severity of illness), but doesn’t prevent infection.
X = NA (neuraminidase)
T/F: Infection by one subtype of Influenza virus doesn’t provide cross-protection against another.
True
Antigenic (shift/drift): small changes that occur frequently within influenza (A/B/C/D). These changes are a result of (X).
Drift;
A or B
X = point mutation (accumulation) in RNA segment that codes for HA
Antigenic (shift/drift): appearance of influenza (A/B/C/D) virus with brand new (X).
Shift;
A;
X = HA (plus/minus new NA)
Reappearance of influenza A virus after decades of absence is example of antigenic (shift/drift). Is this capable of causing pandemic disease?
Shift;
Yes
(Pandemic/Epidemic) outbreak of influenza is confined to one location, generally during (X) season.
Epidemic;
X = winter
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.
Epidemic;
Children (acute febrile rep illness)
X = 2-3 week
Y = 2-3 month
T/F: Increase in abseneeism from work/school is early manifestation (an indication) of epidemic flu outbreak.
False - late manifestation
Epidemic outbreaks have attack rates (in general population) of (X)%. And pandemics?
X = 10-20
Pandemics: exceed 50%
(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.
Pandemic;
X = epidemics
Average influenza incubation period:
2 days (range: 1-4 days)
Influenza virus: spreads to (X) tissue layer and targets/destroys (Y) cells. This results in the characteristic (Z) symptoms.
X = Respiratory tract epithelium Y = ciliated epithelial Z = respiratory
T/F: Quantity of influenza virus is proportional to the severity of symptoms in patient.
True
How might influenza virus infection lead to systemic symptoms?
Proinflammatory cytokine release in blood
T/F: Influenza viral shedding occurs for 2 weeks in adults and children.
False - age-dependent (3-5 days in adults)
T/F: Immunity to influenza virus is type-specific.
False - subtype-specific
What’s the most important (early) clinical finding in influenza infection?
Fever rises to 101-104oF (38-40oC) within 12 hours
Influenza: when (in clinical course) do respiratory symptoms become apparent?
Once systemic symptoms diminish (fever lasts about 1-5 days)
Which patient populations are more susceptible to frequent and severe flu illness?
- Elderly (over 60)
- Smokers
- Pregnant women in trimester 2-3
- HIV pts
Attack rates and higher max temperatures from flu infection may be seen in which patient population?
Kids
Increased frequency of GI symptoms (N/V, abd pain) from flu infection may be seen in which patient population?
Kids
List the respiratory complications that can occur as result of flu infection.
- Primary flu virus pneumonia
- Secondary bac pneumonia
- Mixed bac and viral pneumonia
- Abnormal tracheobronchiolar clearance, airway hyperactivity/dysfunction
List some non-respiratory complications that can occur with influenza virus infection.
- Myositis and rhabdomyolysis
- Myocarditis and pericarditis
- Aseptic meningitis and encephalitis
Definitive diagnosis of influenza virus infection is by:
Isolate from throat/nasal cavity and culture, PCR, or immunofluorescence testing
List the viruses that might be on your differential for influenza infection.
Parainfluenza, Adenovirus, RSV, and Enterovirus
Influenza virus vaccine is (live/dead).
Both exist;
live vaccine only for healthy individuals over 2 y.o.
Killed influenza virus vaccine: formulation is based on (X) strains.
X = prior season’s
T/F: Killed virus vaccine, when matched correctly to epidemic strain, has max 50% efficacy.
False; 60-90%
T/F: All people over 50 should be vaccinated for flu with killed virus vaccine.
True
T/F: All kids under age 5 should be vaccinated for flu with killed virus vaccine.
False - not if under 6 mo old
In elderly, flu vaccination is (X)% effective in preventing hospitalization and pneumonia.
X = 50-60
T/F: Side effects of flu vaccine can include fever, systemic symptoms, and reaction at site.
True
Killed flu vaccine is contraindicated for which population(s)?
Those with anaphylactic hypersensitivity to eggs
List the rare complications that can occur following killed flu vaccine injection.
Guillain-Barré syndrome
List the components that are included in formal nomenclature of influenza virus.
- Type
- Infected animal
- Geographic site of isolation
- Strain number
- Year of isolation
- Subtype
We need new flu vaccines every year due to antigenic (shift/drift).
Drift
Worst case scenario of flu pandemic would mimic that of (X) flu in (Y) year.
X = Spanish Y = 1918
Highly contagious and deadly (killed more americans than all the wars of 20th century!!)
Spanish flu mortality rate was (X)%, unlike other flu epidemics that had (Y)% mortality rate.
X = 2.5 Y = under 0.1
Antiviral drugs must be taken consistently in (X) patient populations to prevent flu infection.
X = immunosuppressed or those allergic to vaccine
