Lecture 17

Question 1

When was Russian Flu emerging

Answer 1

1977

Question 2

When was SARS emerging

Answer 2

2003

Question 3

When was MERS emerging

Answer 3

2012-Present

Question 4

When was West Nile Virus emerging

Answer 4

1999-present

Question 5

When did HIV-1 emerge

Answer 5

1981-present

Question 6

Describe EVD Incubation period

Answer 6

Time from contracting virus to symptoms

Average 11 days - 2-21 days

Average symptom to hospitalization period - 5 days

Average serial interval - 15 days

Average time to death - 10 days

Average time to recovery -17 days

Question 7

What is the prodromal period?

Answer 7

Virus continuously replicates

Triggers immune response and can cause mild-symptoms

Question 8

What is the incubation period

Answer 8

Time between infection with virus and the onset of symptoms

Question 9

How can HIV cause infection

Answer 9

AIDS can undergo 7 year course

• Virus prevalent for first 9 months
• Body produces antibodies for up to 5 years
• CD4 cells decline, antibody production falls
• Virus concentration increases, immune system overwhelmed

Question 10

Case fatality by age range

Answer 10

Highest in 80-90 year old (34.6%)

15.9% in ages 70-79

3.5% in 60-69 year olds

2.9% average

Question 11

Asiatic Flu

Answer 11

Asiatic (1889-90) - 1 million deaths

H3 subtype

Question 12

Spanish Flu

Answer 12

1918-1920 - 40 million deaths

H1N1 subtype

Question 13

Asian Flu

Answer 13

1957-1958 - 1-4 million deaths
H2N2 subtype

Question 14

Hong Kong Flu

Answer 14

1968-69 - 0.75-1 million dwaths
H3N2 subtype

Question 15

Russian flu

Answer 15

1977-78 low deaths
H1N1 subtype

Question 16

Mexican flu

Answer 16

2009-10 - 0.28 million
H1N1 subtype

Question 17

When does antigenic drift occur?

Answer 17

Between pandemics

Question 18

When does antigenic shift occur?

Answer 18

Formation of new pandemics

Question 19

Name some Influenza A reservoirs

Answer 19

Ducks

Seals

Turkeys

Pigs

Question 20

Summary of antigenic shift

Answer 20

Gut and subclinical infection in duck
-> Faecal transmission to chicken causing respiratory disease
-> Passed to humans and pigs
-> Recombination with an existing virus leads to pandemic

Question 21

How do viruses jump species?

Answer 21

Direct jump from ducks to humans

Adaption e.g. Duck to pig to pig to human

Reassortment Human and duck transfer to pig -> pig transfers virus to human

Question 22

Explain the 2009 flu pandemic by antigenic shift

Answer 22

1918 H1N1 -> Classical swine H1N1
? -> North American Avain and H3N2 virus

Classical swine H1N1, North American Avian, H3N2 human virus -> North American swine H3N2 and H1N2
? -> Eurasian ‘Avian-like’ swine H1N1

These 3 viruses form human 2009pdm H1N1