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Clinical Medicine II > influenza (quiz 1, exam 1) > Flashcards

influenza (quiz 1, exam 1) Flashcards

1
Q

epidemiology

influenza virus infeciton is common: __% of the population infected each season; an average of __ annual influenza associate deaths in the US

A
  • 10-20%
  • 50,000
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2
Q

epidemiology

most influenza related mortality occurs indirectly as a result of complications of influenza, and the 2 main complications are _

A
  1. secondary bacterial pneumonia (including post-influenza MRSA pneumonia)
  2. cardiovascular compromise in pts with preexisting congestive heart failure (CHF) or coronary artery disease (CAD)
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3
Q

epidemiology

influenza infection occurs via __

A

aerosolized secretions (in conctrast with rhinoviruses/cold viruses, which are usually spread via fomites)

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4
Q

epidemiology

annual variation in the __ (3) enables influenza viruses to evade antibodies developed during previous seasons form infection or vaccination

A
  1. glycoproetines
  2. hemagglutinin (HA)
  3. neuraminidase (NA)
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5
Q

epidemiology

the usual mechanisms of antigenic variation, occuring in both influenza A and B, is referred to as

A

antigenic drift

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6
Q

epidemiology

antigenic drift occurs through constant and ongoing small mutation of __(2) during __

A
  • HA (hemagglutinin) and NA (neuraminidase)
  • the replicaiton cycle of the virus
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7
Q

epidemiology

people previously infected by strains differing by antigenic drift often have some antibody __ with the new strain, and are more likely to have __ illness

A
  • cross-reactivity
  • milder
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8
Q

epidemiology

antigenic shift only occurs in

A

influenza A

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9
Q

epidemiology

antigenic shift definition

A

an abrupt and major change via gene re-assortment resulting in a new HA (hemagglutinin) or NA (neuraminidase)

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10
Q

epidemiology

__ cross-reactivity exists between previous strains and new strains of influenza A occurring via antigenic shift

A

little or no

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11
Q

epidemiology

new strains occuring via antigenic __ have been responsible for global influenza epidemics and pandemics including __ (2)

A
  • shift
    1. 2009 influenza A H1N1 swine-origin influenza pandemic
    2. 1918 Spanish flu (40 million people worldwide died)
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12
Q

epidemiology

multiple strains of influenza A exist within __ populations, most of which __ transmissiable to humans

A
  • fowl
  • are not
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13
Q

epidemiology

one strain that is highly pathogentic to fowl and has been transmitted to humans is __ influenza A (__)

A
  • avian
  • H5N1
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14
Q

__ is an exceedingly rare zoonotic infection spread by contact with birds

A

avian influenza A (H5N1)

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15
Q

epidemiology

symptoms of avian influenza A (H5N1) include __(3) preceding pneuomonitis by an average of __ days; pneumonitis may progress radpidly to __ and __

A
  1. fever
  2. watery diarrhea
  3. leukopenia
    - 7 days
    - respiratory distress
    - acute respiratory distress syndrome
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16
Q

epidemiology

__ could adapt avain influenza A (H5N1) to adapt it to a human host and to human to human transmission

A

minor genetic changes

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17
Q

clinical features

infection with the influenza A and B viruses cause a spectrum of disease, from __ to __

A
  • asymptomatic
  • serious systemic illness
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18
Q

clincial features

symptoms usually occur after an incubation period between __ and __ hours (peak of __)

A
  • 18 and 72 hours
  • viral titer
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19
Q

clinical features

the virus titer then declines rapidly (after the peak at __ hours) and is no longer detectable within __ to __ days of initial infection

A
  • 18-72 hours
  • 5-10 days
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20
Q

clinical features

risk of contagion is believed to be minimal __ days after symptom onset in otherwise healthy pts

A

7 days

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21
Q

clinical featues

viral carriage and shedding maybe much longer in indivuduals with __

A

compromised immunity

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22
Q

symptoms

classically begin with abrupt onset of __ and __ such that the hour of __ may sometimes be pinpointed

A
  • fever
  • malaise

onset

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23
Q

symptoms

7 main symptoms

A
  1. fever, with or without rigors
  2. mayalgias (often of the back and large muscels in the extremities)
  3. malaise/lethargy
  4. non-productive cough and sore throat
  5. delirium
  6. rash

7, abdominal pain, diarrhea

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24
Q

symptoms

older individuals may present with fever, chills, and malaise without any __ complaints; also eldery pts can present with __ and __ without fever or respiratory symptoms

A
  • respiratory
  • lassitude
  • confusion
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25
Q

symptoms

fever > __ and __ in infuenza season is highly predective of influenzza infeciton in those >__yo

A
  • 38C (100.4F)
  • cough
  • 4yo
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26
Q

clinical findings

7 main ones

A
  • flushed face and toxic appearance
  • hyperemic mucosal membranes
  • clear naseal discharge
  • tender lymphadenopathym (esp. neck)
  • rales or rhonchi may be auscultated in few than 20% of cases
  • dehydration and orthostaic hypotension may also be present
  • epithelial necrosis leading to bacterial superinfection (esp. with pneumococcus or S. aureus)
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27
Q

Diagnosis

usually __ (aka presumptive), __ tests, and __ and __ in areas of epidemic (positive predictive value of __%)

A
  • clinical
  • rapid Ag tests (nasal/pharyngeal)
  • fever and cough

80%

28
Q

influenza vs. common cold

fever

A
  • URI: low grade or absent
  • influenza: common
29
Q

influenza vs. common cold

myalgias

A
  • URI: absent
  • influenza: common
30
Q

influenza vs. common cold

rash

A
  • URI: absent
  • influenza: seen in 5-10% of pts
31
Q

Differential diagnosis

__ is on the DDx for any pt with a cough and fever

A

bacterial pneumonia

32
Q

DDx

a __ pulmonary parenchymal response represented by a __ cough, __ on auscultation, and __ visible on chest radiography help to distinguish bacterial pneumonia from influenza

A
  • purulent
  • productive
  • consolidation
  • inflitrates
33
Q

clinical course

typical duration of severe symtpoms is __ to __ days, but can be (very rarely) more than __ days in healthy adults

A
  • 3-4 days
  • 7 days
34
Q

clinical course

pts with compromised immune systems may have an extended duration of __ and __

A
  • symptoms
  • viral shedding
35
Q

clinical course

history, symptoms, and physical exam can differentiate influenza A from influenza B

A

false

36
Q

clinical course

complications tend to occure more frequently with influenza __

A

A

37
Q

clinical course

influenza __ may cause more abdominal and gastrointestinal symptoms

A

B

38
Q

diagnosis

influenza season occurs from __ to __ in the northern hemisphere, although the peak of activity in any area genreally lasts less than __ weeks

A
  • october to april
  • 6 weeks
39
Q

diagnosis

during the peak activity, over __% of pts with fever and cough have influenza

A

30%

40
Q

diagnosis

influenza is exceedinly rare during the __ season

A

-summer

41
Q

diagnosis

the standard laboratory diagnosic method is a __ for viral antigen

A

rapid immunologic test (e.g. EIA)

42
Q

diagnosis

__ is the most sensitive method and is replaceing viral culture

A

RT-PCR

43
Q

diagnosis

__ is rapid and has 40-80% snesitivity when compared to __, which takes 5-7 days

A
  • EIA
  • viral culture
44
Q

diagnosis

given the low sensitivity of immunologic tests for viral antigens, __ is becoming a standard diagnostic approach

A

RT-PCR

45
Q

treatment

class of antiviral drug that treats influenza A only (2)

A
  1. adamantines: high levels of resistance to these and tehrefore are NOT USED
  2. rimantadine
46
Q

treatment

class of antiviral drug that treats influenza A and B

A

neuraminidase inhibitors

47
Q

treatment

adamantines is an antiviral drug class used to treat influenza __

A

A (not used though because high levels of resistance to these)

48
Q

treatment

rimantadine is an antiviral drug class used to treat influenza

A

A

49
Q

treatment

neuraminidase inhibitors is an antiviral drug class used to treat influenza __

A

A and B

50
Q

treatment

oseltamivir (Tamiflu): is what type of drug class, dosing/duration, ages, comments

A
  • neuraminidase inhibitor (treats influenza A and B)
  • 75mg, 2x daily, for 3-5 days (within 48 hours)
  • infants to adults
  • infant to 12yo dose based on weight; N/V side effects; reduced dosing in pts with CKD
51
Q

treatment

zanamivir (Relenza): drug class, dosing/duration, ages, comments

A
  • neuraminidase inhibitor (treats influenza A and B)
  • 10 mg, 2 inhalations, 2X daily for 3-5 days withing 48 hours
  • greater than 7yo
  • inhaler; side effects in contraindicated in asthma and COPDS
52
Q

treatment

peramivir: drug class

A
  • neuraminidase inhibitor (treats influenza A and B)
  • available for emergencies with severly ill pts
53
Q

treatment

neuraminidase inhibitors function by inhibiting viral __; they reduce the duration and severity of __ and the duration of __

A
  • propagation
  • symptoms
  • viral shedding
54
Q

treatment

antivirals must be started __ to provide clinical benefit in otherwise healthy adults because the majority of viral __ occurs __ in influenza

A
  • early
  • reproduction
  • early
55
Q

treatment

first dose should be givin within __ of symptom onset; after __ there is limited evidence of benefit among pts with intact immune systems

A
  • 24 hours
  • 48 hours
56
Q

treatment and prevention

CDC reecommnedation of anativiral treatment for any individual with suspected or confirmed influenza who (3/f)

A
  1. is hospitalized
  2. has sever, complicated or progressive illness
  3. is at high risk for influenza complication

a. less than 2 yo or greater than 65 yo
b. chronic pulmonary, cardiac, renal, hepatic, hematologic, or metabolic disease
c. immunosuppression including HIV
d. pregnant women
e. BMI>40
f. resident in nursing home

57
Q

treatment

prophylazix: duration of drug use, when used

A
  • usually 7 days
  • used during the week of peak influenza activity
58
Q

treatment

criteria for selecting pts for immunoprophylaxis include (4)

A
  1. persons at high risk for influenza who were vaccinated after teh onset of an influenza outbreak
  2. persons with significant immune deficiency during an outbreak
  3. individuals unable to receive influenza vaccinations due to contraindications
  4. for control of an outbreak in a chronic care institution
59
Q

prevention

4 ways to prevent influenza

A
  1. vaccination
  2. good hand hygeine
  3. unclear wheter facemasks are effective at reducing risk
  4. respirator masks (N95) filter 95% of airborne particles; should be worn by helath care professionals when caring for pts with suspected influenza
60
Q

complications

secondary bacterial pneumonia organisms are typically these 3

A
  1. Streptococcus pneumonia
  2. Haemophilus influenza
  3. Staphylococcus aureus
61
Q

complications

__ pneumonia is uncommon without preceeding influenza infection

A

Staphylococcus aureus

62
Q

complications: secondary bacterial pneumonia

__, particularly __, is the most improtant pathogen to consider because it can cause a rapidly progressive necrotizing pneumonia and requires selection of antibiotics not usually used for community acquired pneumonia

A
  • Staphylococcus aureus
  • community acquired methicillin resistant S. aureus (CA-MRSA)
63
Q

complications: secondary bacterial pneumonia

the pattern of secondary bacterial pneumonia usually follows a cours of __

A

initial improvement in symptoms and resolution of fever followed by clinical decline 4-10 days later

64
Q

Influenza pneumonia with progression over 1wk

A

A. poorly defined nodular opacities and small areas of consolidation in the right middle and lower lung zones

B. extensive bilateral consolidaiton and poorly defined nodular opacities; also noted are an endotracheal tube and central venous line

65
Q

complications

influenza infection also increases the risk for __ mortality, including death from __, __, and __

A
  • caradiovascular
  • stroke
  • myocardial infarction
  • congestive heart failure
66
Q

complications

cardiac mortality associated with influenza is highest among individuals greater than __yo

A

60yo

Clinical Medicine II (11 decks)

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