respiratory

Question 1

How many types of influenza are there?

Answer 1

4 types

A, B, C, D

Question 2

Who can type A influenza infect?

Answer 2

humans, birds, pigs and other animals

Question 3

What type can cause pandemics?

Answer 3

Type A only

Question 4

What type can cause seasonal epidemics?

Answer 4

Type A and B

Question 5

Who can type B infect?

Answer 5

humans and seals

Question 6

Who can type C infect?

Answer 6

humans and dogs

Question 7

Who can type D infect?

Answer 7

pigs and cattle

no known human infections

Question 8

What does haemagglutinin (HA) bind to?

Answer 8

binds to cell surface (sialic acid in the host epithelial cells of the respiratory tract)

Question 9

Role of haemagglutinin

Answer 9

Responsible for virus penetration, mediates fusion between virus and cell
Involved in immune response

Question 10

Role of neuraminidase (NA)

Answer 10

Assist in virus release from cell

Question 11

What is present on the lipid membrane of the influenza A virion

Answer 11

HA, NA and M2 protein

Question 12

How many different types of HA and NA types of capsid proteins are there?

Answer 12

18 HA

11 NA

Question 13

How are influenza A classified

Answer 13

Based on HA and NA
3 HA types
2 NA types

Question 14

How are influenza B classified

Answer 14

Victoria and Yamagata

Question 15

Full nomenclature for influenza classification

Answer 15

Group, Location, Year of isolation

Question 16

What types of cells do influenza infect

Answer 16

Epithelial cells of respiratory tract

Question 17

Transmission of influenza amongst human-human

Answer 17

direct contact-inhaling respiratory droplets

indirect contact with fomites (touch eyes, nose or mouth)

Question 18

What is the incubation period for influenza

Answer 18

2 days (range 1-4)

Question 19

When does the virus shed

Answer 19

Present before disease onset

Continues 2-5 days post resolution of symptoms

Question 20

Natural reservoir of influenza

Answer 20

Wild waterfowl, domestic ducks, chickens, horses, pigs

Question 21

Source of influenza A viruses

Answer 21

Start as avian influenza viruses and then become endemic

Question 22

How does animal-animal transmission of influenza occur

Answer 22

Virus shed in saliva, nasal secretions and faeces

Question 23

How does transmission between animal-human occur

Answer 23

contact with infected livestock (poultry and pigs)

Question 24

What leads to evolution of new influenza strains (seasonal epidemic)?

Answer 24

Antigenic drift
Replication of RNA genome is error prone and leads to amino acid mutations
Mutations in antigenic regions allows virus to escape from neutralisation by antibodies from prior infections/vaccination
New variants results in seasonal epidemics

Question 25

What leads to the creation of pandemic viruses?

Answer 25

Antigenic shift This is through reassortment (the exchange of RNA between viruses inside a host cell). Two viruses co-infect a cell and pool their genetic material creating numerous, genetically diverse, progeny viruses

Question 26

Which population has the highest notifications and hospitalisations?

Answer 26

elderly and children <5 years

Question 27

Diagnosis

Answer 27

Nose or throat swab Electron microscopy: morphological appearance Isolate in culture and perform rapid antigen tests PCR

Question 28

What diagnostic method allows us to type and subtupe the viral strain?

Answer 28

PCR Type A or B HA and NA subtypes Test for resistance mutations

Question 29

What are the two classes of drugs that can be used to treat influenza?

Answer 29

Neuraminidase inhibitors | Adamantanes (M2 ion channel blockers)

Question 30

Name NA inhibitors

Answer 30

Tamiflu-Oseltamivir (oral) Relenza-Zananmivir (oral inhalation) Resistance developing to Tamiflu

Question 31

Are NA inhibitors active against type A and B

Answer 31

YEs

Question 32

Are Adamantanes active against type A and B

Answer 32

No only against influenza A | 2 drugs" Amantadine and Rimantadine

Question 33

Vaccine composition for influenza

Answer 33

Annual vaccines that protect against currently circulating strains. Decision made by WHO committee.

Question 34

What is a key requirement for vaccine strains in | vaccine production?

Answer 34

Must grow well in eggs to meet the high demand for vaccine doses

Question 35

How are the desired HA and NA strains produced?

Answer 35

Strains with desired HA and NA genes undergo reassortment with egg-adapted strains, which are then purified and inactivated

Question 36

What are the conditions required for a pandemic

Answer 36

Emergence of new subtype A strain New virus infects and spreads efficiently in humans New virus causes serious illness and death Subtypes have not circulated for a long time, thus little to no immunity to new virus

Question 37

Spanish flu (1918-19) subtype

Answer 37

H1N1

Question 38

How much of the world's population was affected by the Spanish flu

Answer 38

50% (40-50 million deaths)

Question 39

Did co-infections occur in people infected with Spanish flu

Answer 39

Yes in 95% of deaths during this pandemic | Bacterial (S. pneumoniae)

Question 40

What age group did the Spanish flu affect

Answer 40

20-40 years old

Question 41

Asian flu (1957-58) subtype

Answer 41

H2N2

Question 42

How did Asian flu subtype emerge?

Answer 42

Antigenic shift | H1 to H2

Question 43

What age group did Asian flu affect the most

Answer 43

Highest infection rates: School children (aged 5-19) | Highest death: elderly

Question 44

Hong Kong flu (1968-69) subtype

Answer 44

H3N2

Question 45

How did Hong Kong flu subtype emerge?

Answer 45

``` Antigenic shift (reassortment between seasonal H2N2 and avian influenza viruses) H2 to H3 ```

Question 46

Swine flu (2009) subtype

Answer 46

H1N1 | Started in Mexico and spread globally

Question 47

What age group did Swine flu affect the most

Answer 47

Children and young adults aged 12-22

Question 48

Co morbidity associated with swine flue

Answer 48

secondary bacterial pneumonia

Question 49

Why is transmission of avian strains to human rare?

Answer 49

sialic acid receptors are different receptors for human viruses are alpha-2,6-linked sialic acid receptors for avian viruses are alpha-2,3-linked sialic acids