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ICM > 2: Infuenza > Flashcards

2: Infuenza Flashcards

1
Q

what questions arose after the 1918 flu?

A
  • why did vaccines against bacteria work?
  • why were younger people mostly affected?
  • did treatment contribute to death?
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2
Q

what was the worst side effect of the 1976 flu shot?

A

Guillain-Barre

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3
Q

what questions arose after the 1976 swine flu?

A
  • are the government solutions worse than the problems it creates?
  • are vaccines safe?
  • why didn’t the 1976 flu become a pandemic?
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4
Q

3 main types of flu, who is infected by each?

A

A,B,C

  • A: humans, animals -> cause pandemics
  • B: only humans -> does NOT cause pandemics
  • C: mild disease only
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5
Q

what purpose do the 2 flu surface proteins serve?

A

targets for neutralization by Ab

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6
Q

what are the 2 flu surface proteins, and how many serological types of each are there?

A

hemaglutinin (H1-H15)

neuraminidase (N1-N10)

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7
Q

how can Influenza A types be further named beyond HxNx?

A

according to where they were first identified, their lineage number, and the year isolated

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8
Q

mutation rate of flu and why

A

high mutation rate b/c RNA viruses

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9
Q

describe antigen drift of flu

A

virus strains change their sequence of H1 and N1 proteins from year to year -> ensures the hosts won’t have neutralizing Abs to future strains

when virus acquires new hemaglutinin and neuraminidase genes

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10
Q

how are the genes of influenza organized?

A

each gene is encoded on a separate strand of RNA

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11
Q

describe re-assortment of influenza

A
  • when virus envelope is formed, gene segments from different viruses that have infected the same cell can be incorporated into the virus
  • allows viruses to easily gain new genes
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12
Q

what one animal is responsible for the origin and spread of influenza A to all other animals?

A

duck

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13
Q

first major bird flu, what pandemic was it responsible for?

A

H1N1 -> 1918 Spanish flu

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14
Q

H2N2

A

-

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15
Q

H3N2

A

-

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16
Q

next pandemic

A

-

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17
Q

how long will a strain circulate?

A

unpredictable - typically one strain that circulates for years causing pandemics

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18
Q

transmission of flu

A
  • large droplets like from sneezing, coughing
  • close contact (large drops don’t stay suspended in air)
  • contaminated surfaces probably not important
  • no chance of getting it from pork or chicken meat
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19
Q

clinical presentation of flu

A
  • fever (most common), headache, myalgia, fatigue
  • cough, sore throat and nasal discharge soon follow
  • fatigue and weakness may last for weeks
20
Q

what symptoms/signs are NOT typical features of flu?

A
  • nausea
  • vomit
  • diarrhea
21
Q

complications of flu

A
  • viral pneumonia (goes beyond URT into lungs)
  • bacterial pneumonia (S. pneumoniae, S. aureus)
  • myositis
  • rhabdomyolysis
  • MI
  • encephalitis, encephalopathy
  • Reye’s syndrome (actually caused by aspirin given to kids - get hepatic encephalopathy)
22
Q

things unique to Spanish flu of 1918:

-

A
  • infection started out w/ typical sx, but worsened after several days
  • bacterial pneumonia was most common cause of death
  • aspirin was given in very high doses
  • vaccines made from killed bacteria and injected seemed to have improved mortality
23
Q

things unique to Bird Flu, H5N1:

-

A
  • affects mostly children and young adults
  • very high mortality rates - 60%
  • usually a resp illness, but often has diarrhea and neuro sx
  • little person-to-person transmission
24
Q

Avian flu H7N9:

  • where?
  • who is affected?
  • what does it give you?
  • transmission?
A
  • primarily occurred in China in early 2013
  • elderly more affected
  • severe resp illness common
  • no evidence of sustained person-to-person transmission
25
Q

variant H3N2 flu:

-

A
  • found in Indiana at state fairs in 2012, 2013
  • cases had close contact with pigs
  • appears to be combo of 2009 H1N1 + pig H3N2 strain
  • no sustained transmission, mild disease in humans so far
  • young kids don’t have Abs, while those 10-14 y/o have some (exposure to virus that circulated in 90s)
26
Q

mortality during a mild year in US

A

3000 deaths, mostly in elderly

27
Q

mortality during severe years and pandemics

A

about 45,000 deaths, many in kids and young adults

28
Q

what is the gold standard of diagnosis? problem w/ it?

A

viral culture, but takes days

29
Q

what is the best test for diagnosis? problem w/ it?

A

RT-PCR - highly sensitive and good turn-around, but more expensive

30
Q

other ways to diagnose?

A
  • rapid Ag tests available, but only moderate sensitivity

- in flu season, sx often enough for diagnosis

31
Q

older agents for antiviral treatment:

A
  • Amantadine and Rimantadine

- all current strains are resistant to these

32
Q

newer antivirals for treatment:

A

nruaminidase inhibitors Oseltamivir (Tamiflu) and Zanamivir

33
Q

effectiveness of antiviral treatments?

A

at best reduce sx by 1-2d, but only if given w/i 48h of sx onset
-drugs shown to reduce mortality in 2009 H1N1 outbreak, but not clear if antivirals reduce mortality in other settings

34
Q

administration of zanamivir

A
  • oral inhalation

- IV also available

35
Q

what is the new investigational IV drug?

A

peramivir

36
Q

how often does a new vaccine need to be made? why?

A

every year due to antigenic drift in the predominant circulating strains - use educated guesses to figure out which strains will be predominant in the upcoming flu year

37
Q

how long does it take to make a new vaccine?

A

9 mo

38
Q

how are vaccine strains grown?

A

in eggs - 1 egg makes enough vaccine for 1 shot

-then eggs with virus are purified, virus inactivated with formaldehyde

39
Q

how is the current vaccine further purified? why?

A

to have only the HA and N ag’s - called a ‘split’ vaccine - supposedly less side effects

40
Q

composition of current vaccines

A

have either:

  • two A strains and one B strain (trivalent)
  • two A and two B (quadrivalent)
41
Q

what does the current vaccine have for good measure?

A

2009 H1N1

42
Q

composition of 2015 vaccine

A

H3N2 strain and 1 or 2 B strains

43
Q

what vaccine is available for people w/ egg allergies?

A
  • cell culture-based vaccine

- also an entirely recombinant vaccine

44
Q

who is allowed to get the live, attenuated vaccine?

A

those

45
Q

advantage of live, attenuated vaccines?

A

may give better protection, but not proven

46
Q

vaccine effectiveness

A
  • most effective in children
  • in those >65 y/o, not very effective (20-25%)
  • vaccines are thought to provide only non-sterilizing immunity, so may still allow infection
  • main outcome is prevention or improvement of disease

ICM (26 decks)

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