2: Infuenza

Question 1

what questions arose after the 1918 flu?

Answer 1

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

Question 2

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

Answer 2

Guillain-Barre

Question 3

what questions arose after the 1976 swine flu?

Answer 3

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

Question 4

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

Answer 4

A,B,C

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

Question 5

what purpose do the 2 flu surface proteins serve?

Answer 5

targets for neutralization by Ab

Question 6

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

Answer 6

hemaglutinin (H1-H15)

neuraminidase (N1-N10)

Question 7

how can Influenza A types be further named beyond HxNx?

Answer 7

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

Question 8

mutation rate of flu and why

Answer 8

high mutation rate b/c RNA viruses

Question 9

describe antigen drift of flu

Answer 9

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

Question 10

how are the genes of influenza organized?

Answer 10

each gene is encoded on a separate strand of RNA

Question 11

describe re-assortment of influenza

Answer 11

• 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

Question 12

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

Answer 12

duck

Question 13

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

Answer 13

H1N1 -> 1918 Spanish flu

Question 14

H2N2

Answer 14

-

Question 15

H3N2

Answer 15

-

Question 16

next pandemic

Answer 16

-

Question 17

how long will a strain circulate?

Answer 17

unpredictable - typically one strain that circulates for years causing pandemics

Question 18

transmission of flu

Answer 18

• 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

Question 19

clinical presentation of flu

Answer 19

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

Question 20

what symptoms/signs are NOT typical features of flu?

Answer 20

• nausea
• vomit
• diarrhea

Question 21

complications of flu

Answer 21

• 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)

Question 22

things unique to Spanish flu of 1918:

-

Answer 22

• 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

Question 23

things unique to Bird Flu, H5N1:

-

Answer 23

• 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

Question 24

Avian flu H7N9:

• where?
• who is affected?
• what does it give you?
• transmission?

Answer 24

• primarily occurred in China in early 2013
• elderly more affected
• severe resp illness common
• no evidence of sustained person-to-person transmission

Question 25

variant H3N2 flu: | -

Answer 25

- 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)

Question 26

mortality during a mild year in US

Answer 26

3000 deaths, mostly in elderly

Question 27

mortality during severe years and pandemics

Answer 27

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

Question 28

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

Answer 28

viral culture, but takes days

Question 29

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

Answer 29

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

Question 30

other ways to diagnose?

Answer 30

- rapid Ag tests available, but only moderate sensitivity | - in flu season, sx often enough for diagnosis

Question 31

older agents for antiviral treatment:

Answer 31

- Amantadine and Rimantadine | - all current strains are resistant to these

Question 32

newer antivirals for treatment:

Answer 32

nruaminidase inhibitors Oseltamivir (Tamiflu) and Zanamivir

Question 33

effectiveness of antiviral treatments?

Answer 33

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

Question 34

administration of zanamivir

Answer 34

- oral inhalation | - IV also available

Question 35

what is the new investigational IV drug?

Answer 35

peramivir

Question 36

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

Answer 36

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

Question 37

how long does it take to make a new vaccine?

Answer 37

9 mo

Question 38

how are vaccine strains grown?

Answer 38

in eggs - 1 egg makes enough vaccine for 1 shot | -then eggs with virus are purified, virus inactivated with formaldehyde

Question 39

how is the current vaccine further purified? why?

Answer 39

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

Question 40

composition of current vaccines

Answer 40

have either: - two A strains and one B strain (trivalent) - two A and two B (quadrivalent)

Question 41

what does the current vaccine have for good measure?

Answer 41

2009 H1N1

Question 42

composition of 2015 vaccine

Answer 42

H3N2 strain and 1 or 2 B strains

Question 43

what vaccine is available for people w/ egg allergies?

Answer 43

- cell culture-based vaccine | - also an entirely recombinant vaccine

Question 44

who is allowed to get the live, attenuated vaccine?

Answer 44

those

Question 45

advantage of live, attenuated vaccines?

Answer 45

may give better protection, but not proven

Question 46

vaccine effectiveness

Answer 46

- 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