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MIIM20002 - Microbes, Infections, Responses > Lecture 18 - Emerging Viral Disease > Flashcards

Lecture 18 - Emerging Viral Disease Flashcards

1
Q

What is an emerging viral disease?

A
  • Newly appeared

OR

  • Previously existed, but rapidly increase in incidence or geographical range
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2
Q

What is an emerging viral disease?

A
  • Newly appeared

OR

  • Previously existed, but rapidly increase in incidence or geographical range
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3
Q

What are some examples of emerging viral disease?

A

SARS-CoV
HIV
Ebola

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4
Q

What are some factors that lead to the emergence of new disease?

A
  • Mutation rate of viruses
  • Ecological changes
  • Human demographics and behaviour
  • Air travel
  • Technology and industry
  • Public health measures
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5
Q

Most emerging viral diseases are…

A

Zoonoses

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6
Q

What are some examples of zoonoses?

A

Birds: influenza
Monkeys: HIV
Bats: SARS-CoV

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7
Q

What does SARS stand for?

A

Severe acute respiratory syndrome

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8
Q

Describe what happened in the SARS epidemic

A 
2003
First cases in China
Spread to 32 countries
800 people died
$20 billion
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9
Q

What are the symptoms of SARS?

A

Fever
Cough
Shortness of breath
Chest X ray –> pneumonia

+ + exposure to SARS patient

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10
Q

How was SARS transmitted?

A

Person - person

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11
Q

What are some examples of emerging viral disease?

A

SARS-CoV
HIV
Ebola

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12
Q

What are some factors that lead to the emergence of new disease?

A
  • Mutation rate of viruses
  • Ecological changes
  • Human demographics and behaviour
  • Air travel
  • Technology and industry
  • Public health measures
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13
Q

Most emerging viral diseases are…

A

Zoonoses

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14
Q

What are some examples of zoonoses?

A

Birds: influenza
Monkeys: HIV
Bats: SARS-CoV

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15
Q

What does SARS stand for?

A

Severe acute respiratory syndrome

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16
Q

Describe what happened in the SARS epidemic

A 
2003
First cases in China
Spread to 32 countries
800 people died
$20 billion
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17
Q

What are the symptoms of SARS?

A

Fever
Cough
Shortness of breath
Chest X ray –> pneumonia

+ + exposure to SARS patient

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18
Q

How was SARS transmitted?

A

Person - person

Airbone droplets from sneezing

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19
Q

What was interesting about the spread of SARS?

A

20% of cases were Health Care workers –> defied normal control measures

Superspreaders: some people spread the virus to a huge number of people

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20
Q

What type of virus is SARS?

A

Corona virus

21
Q

What is the natural host of SARS?

What other animal was a host to a similar corona virus?

A

Bats

Civit cat

22
Q

Which subtypes of influenza are endemic in man?

A

Type A:
H1N1
H3N2

23
Q

Which cells in man are infected by influenza?
How about in birds?

What is the significance of this?

A

Humans: Cells bearing SA a2-6 Galactose

Birds: cells bearing SA a2-3 Gal

Normally prevents avian viruses from infecting man

24
Q

What happens when the aviacn virus infects man?

Why?

A

Pandemic

Because no one has any antibody to the new subtype

25
Q

How is antigenic shift different from antigenic drift?

Describe antigenic shift

A

Shift:
• bigger change in a shorter period of time
• two different strains / subtypes coming together
• mixture of surface antigens

26
Q

What is the cause of a pandemic?

A

Antigenic shift

This is when there is suddenly a new subtype that can infect man

27
Q

What were the influenza pandemics seen in the 20th century?

A

Spanish flu: H1N1
Asian flu: H2N2
Hong Kong flu: H3N2

28
Q

What happens to the existing subtype when there is a pandemic?

A

The old subtype is replaced.

eg. H3N? –> H1N1 in Spanish flu

29
Q

How do new human subtypes come about?

A

Antigenic shift
Mechanism:
• Reassorment
• direct invasion with avian strain, then mutation

30
Q

Describe what happened in the Spanish flu pandemic?

A

25-30% population infected
50 million deaths
15-30 yo mainly affected
During WWI

31
Q

What were the symptoms of Spanish flu?

A

Pulmonary oedema
Haemorrhage
Cyanosis (purple lips)

32
Q

Why was the H1N1 of the Spanish flu so lethal?

A

Don’t know yet, but sequences are currently being studied by Reverse genetics

33
Q

What is the subtype of Avian influenza?

A

H5N1 HPAI (Highly pathogenic avian influenza)

34
Q

What happens to birds that are infected with H5N1 HPAI?

A

Infects systemically and rapidly brings death

35
Q

Does H5N1 infect man?

A

Yes –> lethal

However, it can not be spread from Human-Human

36
Q

How can HPAI infect systemically?

A

The cleavage site on HA has mutated

It can now be cut by an enzyme found all over the body

37
Q

What is the potential route for an H5N1 pandemic?

A
  1. Mutation –> Becomes virulent to poultry
  2. Infects man directly with low efficiency
  3. Antigenic drift, so that it affects man with high effiency

PANDEMIC

38
Q

In 1997, there were 20 cases of Avian flu in man. How was the epidemic halted?

A

Culling of poultry

39
Q

What is the fatality rate of avian flu?

How does this compare to seasonal epidemic influenza?

A

H5N1: 60%

Seasonal epidemic influenza: 0.01%

40
Q

Which drugs are effective against avian flu?

A

NA inhibitors

41
Q

Describe the process of reassortment?

A

In a ‘mixing vessel’
• Pig cells have surface receptors that allow invasion by both human and avian influenza
• Single cell infected with both strains at once
• reassortment
• New strain:
- human internal proteins
- avian HA and NA

42
Q

What does reassortment bring about?

A

Antigenic shift

43
Q

Describe the origin of the 2009 H1N1 pandemic?

A

1918 H1N1 in North America
+ Swine viral genes

2009 Pandemic H1N1

44
Q

Describe the infection caused by 2009 H1N1 Swine flu

A 
Same as seasonal influenza:
• fever
• cough
• muscle pains
• malaise
• fatigue

NB not systemic

45
Q

Compare lethality of Swine flu, Avain flu and seasonal influenza

A

Avian flu is highly lethal

Both Swine flu and seasonal influenza aren’t very lethal, unless the individual is immunosuppressed

46
Q

Compare replicative ability of seasonal flu and swine flu

A

Swine flu has a greater ability to replicate in lungs

Younger people are getting viral pneumonia

47
Q

How is Swine flu treated?

A

NA inhibitors

48
Q

Can we make vaccines against H5N1 now for when it becomes a pandemic?

A

Yes, but they probably wouldn’t be effective due to antigenic drift

49
Q

How can we treat H5N1 if it becomes a pandemic?

A

NA inhibitors

However, we won’t be able to produce enough

MIIM20002 - Microbes, Infections, Responses (32 decks)

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