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Respiratory viruses Flashcards

(62 cards)

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1
Q

Why do birds hardly ever get viral respiratory infections?

A

Birds have separate inspiratory and expiratory bronchi - flow through system causes them to hardly get viral infections of respiratory tract

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2
Q

Why is the common adage that being in an area that is cold, gives you a cold, wrong?

A

Exposure to cold weather does not make you sick, but if sufficiently bad, can cause one to become immunosuppressed and be susceptible to respiratory virus

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3
Q

Respiratory infections cause about ___% of acute illnesses that result in loss of time from work.

A

80

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4
Q

What percentage of respiratory infections are viral?

A

80%

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5
Q

Influenza and pneumonia cause long _______.

A

absences

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6
Q

Describe the infectious cycling and incubation period of respiratory viruses.

A

respiratory viruses have seasonality

they have short incubation periods - 1-4 days

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7
Q

How contagious are respiratory viruses?

A

Very

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8
Q

What group do influenza viruses belong to?

A

Orthomyxovirus group

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9
Q

Describe the morphology of influenza viruses, and genome.

A

Enveloped, single (-ve) stranded RNA virus

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10
Q

What are the different types of influenza viruses?

What do they infect?

A

A, B, C
B and C infect only humans, do not cause pandemics
A is naturally found in the gut of waterfowl but can infect poultry, swine, horses and humans

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11
Q

What are the surface proteins of Influenza virus?

A

Hemagglutinin

Neuraminidase

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12
Q

How many subtypes of hemagglutinin are there? What does hemagglutinin do?

A

15
Binds to oligosaccharides (on cell surface) containing terminal sialic acids
i.e. allows adsoprtion

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13
Q

How many subtypes of neuraminidase are there?

A

9

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14
Q

What does neuraminidase mediate?

A

Budding off from host cell

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15
Q

Point mutations in the genes that code for hemagluttinin and neuraminidase which produces minor antigenic variations from year to year within the same HA/NA type

A

antigenic drift

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16
Q

Why is antigenic drift usually not much of an issue?

A

The change is often not significant and people often have cross reactivity.

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17
Q

What is the danger of antigenic shift?

A

Two different influenza viruses infect the same host cell, recombine genes and spit out a completely new virus - has the potential to cause a pandemic.

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18
Q

What are key characteristics of antigenic shift?

A

Random
can happen anywhere
Pandemic strains usually replace previously circulating strains

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19
Q

Pandemic strains of Inlfuenza usually present on average after how many years?

A

10-20 years

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20
Q

Can you have a countdown to a pandemic of influenza?

A

No, it’s random

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21
Q

What are the symptoms/signs of the flu?

How long do they last for?

A

Fever, chills, cough and myalgia

3-5 days

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22
Q

Describe the difference in impact of Influenza based on age.

A

Usually a minor illness in the young and healthy

often fatal in the elderly

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23
Q

For who else can Influenza be fatal?

A

those with cardiorespiratory disease

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24
Q

What does the flu not have, except in children?

A

No vomitting or diarrhea

except for about 25% of kids

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25
What can influenza often trigger that can be fatal?
MIs and strokes
26
What are the major indirect consequences of influenza?
huge in terms of hospitalization, serious loss of school and work time, and mortality
27
Why was the 1889 H2N2 strain particularly deadly for the young?
Overactive immune response (cytokine storm) more prevalent in immunocompetent individuals
28
Which was one of the most devastating influenza strains? What was it called? How many people did it kill? How lethal was it? What was the mortality rate and who was mostly affected?
1918 - H1N1 - Spanish flu killed 40-100 million 50x more lethal than most strains 2.5-5% mortality, esp. in young and healthy
29
The H1 hemagluttinin from the Spanish flu caused what?
Produced an intense immune response
30
What was a very unprecendented symptom caused by the Spanish flu?
Encephalitis lethargica
31
What does encephalitis lethargica cause?
Personality alterations that make a person very persuasive and argumentative
32
How many waves did the Spanish flu come in? Which was worse?
2 | the second was worse
33
What did the Spanish influenza cause?
Secondary bacterial pneumonia or cytokine storms
34
What was the most recent influenza pandemic? | Who was affected?
H1N1 - Swine flu | - affected both pigs and humans (children and young adults)
35
Why was the most recent H1N1 not a serious strain?
lacked the PB1-F2 protein
36
Although this wasn't a serious strain, a certain young hockey player died from it. Why?
Genetic defect causing overabundant interleukin 17 - died of a cytokine storm
37
Canada produced a vaccine but Poland didn't. Were the death tolls different?
No, since it wasn't a deadly strain
38
Why was this pandemic strain particularly non lethal (other than lack of PB1-F2 protein)?
People born before 1957 had cross-reacting antibodies CD8 T cell response limited severity Majority of T cell epitopes were similar to past H1N1 strains
39
What does the PB1-f2 protein do?
Binds to inner mt membrane and sensitizes cells to apoptotic stimuli (TNF-a)
40
Where do Influenza epidemics start? Why?
Usually start in Far East, possibly due to agrarian practices in China (basically fowl mates with chickens, and then passes virus to pigs who have the receptor for bird viruses and human viruses)
41
How is the North american vaccine produced?
Produce trivalent vaccine based on the strain that is circulating in the spring in China - will circulate in the fall here (for the most part)
42
Why is the fear of getting guillain barré a little ridiculous?
can happen after ANY immune stimulus
43
Why is the fear of microcephaly from the zika virus out of proportion?
Need to get it during early pregnancy, pretty rare - if already infected when younger, no issues
44
Describe the influenza virus.
Inactivated whole virus or inactivated virus composed mainly of hemagluttinin also attenuated in flu mist form for kids
45
What is the sick test that we ran out of money for to determine which influenza it is?
multiple real time PCR
46
How can we treat outbreaks of influenza A or B
zanamivir or oseltamivir - antivirals
47
What group do parainfluenza viruses belong to? What are they related to?
Paramyxoviruses | related to mumps
48
What is the genetic organization of paramyxoviruses?
ss RNA (parainfluenza)
49
How are the paramyxoviruses similar to influenza?
Have hemagglutinin and neurominidase
50
Where can you not get mumps if you are post-pubertal?
In the testicles
51
Parainfluenza _ and __ are closely related and cause acute laryngotrachietis, bronchiolitis and pneumonia, mainly in _______ ______.
1 and 3 | young children
52
This is one of the only diseases that you can reliably diagnose over the phone. What is the telltale sign?
Parainfluenzal "croup" (acute laryngotracheitis) | - get barking cough
53
What breaks the spasm of croup?
Cool, moist air breaks the spasm very fast
54
For severe cases of croup, was is done?
Racemic epinephrine (and corticosteroids) and special basinette that blows cool air into the child's face
55
Parainfluenza __ is more serious and causes severe ____ disease in young children.
2 | severe LRT
56
What does parainfluenza 4 cuase? Who can get it?
milder respiratory illness | all age groups
57
Most important cause of respiratory disease in infants (worth remembering).
Respiratory syncytial virus
58
What type of virus is RSV?
paramyxovirus
59
Why is the virus named RSV?
for its ability to produce cell fusion in tissue cultures
60
the symptoms of RSV begin with what? What can they progress to?
Being with rhinitis, progression to bronchiolitis and necrotizing pneumonia - can lead to hypoxia of lungs
61
What is the mortality rate for RSV infection? Which age bracket is more severely affected? Who is at the greatest risk?
0.5-1% younger children more severely affected infants with congenital heart disease or if immunocompromised can have a mortality rate of 15%
62
When Professor Colby legit spazzed out and talked about "It's in the eyes", what virus was being discussed?
RSV

Micro and Immunology (38 decks)

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