Influenza

Question 1

why is influenza so severe

Answer 1

new strain of influenza emerges => pandemic

Question 2

pandemic influenza taken very seriously, why

Answer 2

likely to happen very quickly and kill 10/100 millions

Question 3

when did we have a pandemic of influenza

Answer 3

1918

Question 4

antigen

Answer 4

a molecule that can stimulate an immune response

Question 5

antigen drift (small change)

Answer 5

a random accumulation of mutations in viral genes recognized by immune system = may significantly change the antigens of the virus, and may help it evade the immune system

Question 6

how often to pandemics occur

Answer 6

every 30 years and vary in virulence

Question 7

describe influenza virus

Answer 7

2 different molecules on surface:

• neuraminidase (getting out of cell)
• hemagglutinin (binding of virus to cell)

Question 8

why is influenza virus worse than measles virus

Answer 8

measles: surface proteins never change = vaccine very effective
influenza: surface proteins change over time - different types of hemagglutinin/neuraminidase

Question 9

what affects humans

Answer 9

H: 1,2,3
N: 1, 2

Question 10

why do you get flu after getting a flu shot

Answer 10

1. low efficacy due to antigen drift (can’t get herd immunity)
2. you already had flu
3. it wasn’t influenza

Question 11

why can’t flu vaccine give you flu

Answer 11

dead vaccine (inactivated)

Question 12

antigen shift (large change)

Answer 12

antigenic shift is the process by which 2 different strains of influenza combine to form a new a subtype having a mixture of the surface antigens of the 2 original strains

Question 13

what do antigen shifts lead to

Answer 13

major influenza pandemics

Question 14

what causes antigen shift

Answer 14

. strains of influenza can affect number of different species - limited (due to H)

. humans share strains with pigs

. pigs share strains with birds

Question 15

reassortment

Answer 15

a mixing of the genetic material of two similar viruses that are infecting the same cell

Question 16

why Spanish flu

Answer 16

1918 - end of world war one

censorship - except Spain - neutral

Question 17

human influenza strains

Answer 17

low virulence to humans

highly infectious to humans

Question 18

bird influenza strains

Answer 18

high virulence to humans

low infectiousness to humans

Question 19

reassortment in a pig coinfected with both strains of human + bird influenza

Answer 19

could lead to:

high virulence to humans

highly infectious to humans

Question 20

why strains of influenza have asian names and decent

Answer 20

still a lot of mixing between pigs/animals/humans = small farms / wet markets with live animals - opportunity of reassortment much higher

Question 21

why is there concern with Avian Flu

Answer 21

high mortality

Question 22

morbidity

Answer 22

state of being diseased

Question 23

mortality

Answer 23

death rate

Question 24

what does low mortality mean

Answer 24

not virulent

Question 25

H1N1

Answer 25

easily spread (bind to upper part of respiratory system = highly infectious) rarely fatal (lungs unaffected

Question 26

H5NI

Answer 26

afftect birds - bind to receptors deep in lungs ``` spreads slowly (less infectious/transmitted) often fatal ```

Question 27

why did spanish flu have high mortality

Answer 27

vast majority of people who died from flu 1918 - young/healthy hypothesis: strength of young people killing them

Question 28

cytokine

Answer 28

a substance that is produced by cells of the immune system and can affect the immune response

Question 29

cytokine storm

Answer 29

a potentially fatal immune immune reaction caused by highly elevated levels of various cytokines

Question 30

what does cytokine storm affect

Answer 30

spanish flu 1918 SARS Avian influenza NOT other flu strains

Question 31

why are older people less likely to die from strains

Answer 31

already been exposed

Question 32

preventing influenza deaths

Answer 32

antibiotics (pneumonia kills people) ventilators/steroid drugs (die from respiratory distress) prevent heart attack deaths antiviral drugs (Tamiflu)