Influenza Flashcards

1
Q

What is influenza (illness)?

A
  • a contagious viral respiratory illness
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2
Q

What is the incidence of influenza worldwide?

A
  • 3-5 million cases of severe illness
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3
Q

What is the make-up of the influenza virus?

A
  • single-stranded family of RNA viruses referred to as Orthomyxoviridae
  • classified as wither type A,B, or C
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4
Q

Influenza __ is responsible for up to 90% of epidemic influenza

A

A

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5
Q

What are the different subtypes within influenza A based on?

A
  • based on the surface hemagglutinin (HA) or neuraminidase (NA) glycoproteins
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6
Q

Influenza __ has never been seen in humans

A

C

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7
Q

How is influenza spread?

A
  • respiratory droplets caused by coughing and sneezing
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8
Q

When are most healthy adults able to infect others with influenza?

A
  • 1 day before symptoms start and 5-10 days after becoming sick
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9
Q

What is the typical incubation period of influenza?

A
  • 1-4 days (average 2 days)
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10
Q

The seasonal flu vaccine this year is a _____ vaccine

A

quadrivalent

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11
Q

What is the common clinical presentation of influenza?

A
  • fever
  • muscle pain
  • headache
  • non-productive cough
  • malaise
  • sore throat
  • rhinitis
    (these usually RESOLVE in 1 week of presentation - cough and malaise persist for more than 2 weeks)
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12
Q

What are the general complications of influenza vs a common cold?

A

Influenza: respiratory failure, especially with chronic conditions
Common cold: congestion, sinus or ear infection

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13
Q

Describe the complications of influenza?

A
  • diffuse viral pneumonitis - the clinical syndrome most likely to result in hospitalization (can lead to shock and resp. failure)
  • pneumonia - secondary bacterial infection
  • dehydration
  • worsening of concurrent medical conditions (asthma, diabetes, congestive HF)
  • viral myocarditis is a rate complication
  • acute coronary syndrome
  • exacerbations of chronic pulmonary conditions
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14
Q

What are the bacteria that cause secondary bacterial pneumonia?

A
  • staphylococcus aureus
  • streptococcus pneumoniae
  • hemophilus influenzae
  • other gram negative bacilli
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15
Q

Samples for influenza testing include what?

A
  • nasopharyngeal swab
  • nasal wash
  • nasal aspirate
  • blood for antibodies
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16
Q

A viral culture provides test result in _____ days

A

3-10

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17
Q

Viral culture detects both influenza ___ and ___

A

A and B

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18
Q

What test is done that identifies the presence of influenza A and B viral nucleoprotein antigens in respiratory specimens, and display the result in a qualitative way (positive vs negative)

A

Rapid influenza diagnostic tests

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19
Q

What is the advantages of rapid influenza tests?

A
  • produce quick result in 15 minutes or less
  • simple to perform
  • some RIDRs are approved for office/bedside use
20
Q

What is the disadvantage of rapid influenza tests?

A
  • sensitivity (10-69%) false negative results are common especially when influenza activity is high
  • although specificity is high, false positives can also occur, especially during times when influenza activity is low
  • Some RIDTs distinguish between influenza A or B virus infection while others do not. They do not provide information about influenza A subtypes or specific strain information
21
Q

Describe serological testing

A

involves testing serum samples for influenza antibody to diagnose a recent infection. Two sample are collected, one within the 1st week of illness and the second 2-4 weeks later. If antibody levels are higher in the second sample than the first, it is likely that the influenza virus was present

22
Q

Describe how neuramidase inhibitors work?

A

they bind to the protein of the virus and does not allow the virus to leave and spread throughout the body

  • also cause clumping of the virons and do not allow them to spread
  • 2 mechanisms that neuramidase inhibitors stop the spread
23
Q

____ is extensively converted to its active metabolite by hepatic esterases (drug interactions involving competition for esterase have NOT been reported)

A

Oseltamivir

24
Q

Clearance of oseltamivir carboxylate is by ______ and ______ by an anionic transporter system. Reduce the dose in renal impairment

A

glomerular filtration

tubular secretion

25
Q

____ can decrease the renal excretion of the oseltamivir carboxylate

A

Probenacid

26
Q

What are the most common side effects of oseltamivir?

A

gastrointestinal (nausea, vomiting, diarrhea) - mitigated by ingestion of food

27
Q

What is the most concerning side effects of oseltamivir that is most commonly seen in children?

A

neurological adverse effects (kids being injured or killed by jumps or falls from buildings)

28
Q

How is zanamivir administered?

A
  • administered by dry powder inhaler (not orally bioavailable)
  • severely limits zanamivir’s role in critical illness
29
Q

Only about _______ of an inhaled dose of zanamivir is absorbed systemically?

A

10-20%

30
Q

Is zanamivir significantly metabolized or excreted renally? What is the significance of this?

A

No

- significance is that there is no dosing adjustments needed in individuals with impaired renal or hepatic function

31
Q

When oseltamivir is started within the first 4 days of treatment, what generally happens?

A
  • there is a significant reduction in viral load than those that were left untreated
32
Q

Minimal to no benefit was reported in healthy children and adults when antiviral treatment was initiated in _____

A

more than 2 days

33
Q

When oseltamivir is started within the first 24 hours of illness onset, the median time to illness resolution was shortened by how long?

A
  • by 3.5 days compared with placebo
34
Q

Antiviral treatment is recommended as early as possible for any patients with confirmed or suspected influenza who is:

A
  1. hospitalized
  2. has severe, complicated or progressive illness
  3. at a higher risk of influenza complications
35
Q

Antiviral treatment should be offered to persons at higher risk of influenza complications. These include what?

A
  • children under 2 y/o
  • adults over 65 y/o
  • persons with chronic pulmonary, cardiovascular, renal, hepatic, hematological, metabolic disorders (including DM) or neurologic disorders
  • persons with immunosuppression, including that cause by medications or by HIV infection
  • women who are pregnancy or postpartum
  • persons under 19 y/o who are receiving long term ASA tx
  • First Nations people
  • persons who are morbidly obese
  • residents of nursing homes and other chronic care facilities
36
Q

Combination therapy raises the promise of decreasing _______ and increasing efficacy of therapy. In actuality, however, oseltamivir-zanamivir combination actually _______

A

emergence of resistance
- impaired rate of recovery

IT IS COUNTERPRODUCTIVE

37
Q

Higher doses of oseltamivir may have eradicated the virus faster, but they have no influence on ______

A

survival of the person

38
Q

What is known to be the most effective method for preventing the season influenza virus infection and its complications?

A
  • annual influenza vaccination
39
Q

All people above what age are recommended to get an annual influenza vaccine?

A

6 months of age

40
Q

With a good match influenza vaccination can prevent influenzal illness in _____ of healthy children and adults and ___ of the elderly

A

70-90%

50%

41
Q

What is the preservative used in influenza vaccinations?

A

thimerosal

42
Q

How long does it take for a person to develop immunity from a quadrivalent vaccine?

A

2 weeks

43
Q

Explain the mechanism of vaccine protection?

A

IM administration of inactivated influenza vaccine results in the production of circulating IgG antibodies to the viral hemagglutinin and neuramidase, as well as cytotoxic T lymphocyte response

  • both humoral and cell mediated responses are thought to play a role in immunity to influenza
  • the antibody response after vaccination depends on several factors, including the age of the recipient, prior and subsequent exposure to antigens and the presence of immunodeficiency states
  • humoral antibody levels are generally achieved within 2 weeks of immunization
44
Q

Who should not get vaccinated?

A
  • people who have had a previous anaphylactic reaction to any element of the vaccine
  • people with IgE mediated hypersensitivity to eggs
  • people who are currently experiencing a high fever (because if the fever worsens we do not know if the fever was from the vaccine or a prior illness
45
Q

The influenza vaccine can inhibit the clearance of ____ and _____

A

warfarin
theophyllline
(have not shown any adverse effects however)

46
Q

What are the most common adverse reactions to being vaccinated?

A
  • mild symptoms developing soon after the vaccine and lasting for 1-2 days
  • soreness, redness or swelling where the injection was given - severe breathing problems in minutes to hours in those with severe egg allergies
  • CANNOT cause influenza b/c the virus is not live
  • post vaccination fever may be observed in under 12% of immunized children aged 1-5 y/o