Influenza

Question 1

What type of virus is the influenza virus?

Answer 1

RNA virus

8 segment genome

Question 2

What are the 3 main groups of influenza virus?

Answer 2

A, B, C

Question 3

What type of influenza infects mammals and bird/?

Answer 3

IfA

Question 4

What type of influenza infects only humans?

Answer 4

IfB and IfC

Question 5

What are the main surface proteins on the influenza virus?

Answer 5

Haemagglutinin

Neuraminidase

Question 6

What does the surface protein haemagglutinin do?

Answer 6

Facilitates viral attachment and entry to host cell

Question 7

What does the surface protein neuraminidase do?

Answer 7

Enables new virion to be released from host cell

Question 8

How many different known H antigens are there?

Answer 8

18 differed H antigens

Question 9

How many different known N antigens are there?

Answer 9

11 different N antigens

Question 10

What virus family is influenza part of?

Answer 10

Orthomyxoviridae

Question 11

How does antigenic drift work?

Answer 11

Occurs continually over time, small on-going point mutations in the genes coding for antibody binding sites

Question 12

Does antigenic drift or shift change the antigenic properties and eventually means the immune system can’t combat the virus as well?

Answer 12

Antigenic drift

Question 13

Does antigenic drift or shift cause worse than normal epidemics and vaccine mismatch?

Answer 13

Antigenic drift

Question 14

What is antigenic shift?

Answer 14

Abrupt major change in the virus, resulting in new H/N combinations

Question 15

Each year, what does the flu vaccine contain?

Answer 15

Two A strains
One B strain
- can change year to year

Question 16

What is the genetic change that enables a flu strain to jump from one animal species to another?

Answer 16

Antigenic shift

Question 17

What is the process by which two or more different strains of a virus combine to form a new subtype, resulting in new H/N combinations?

Answer 17

Antigenic shift

Question 18

What can lead to pandemics: antigenic drift or shift?

Answer 18

Antigenic shift

Question 19

How is pandemic flu different to seasonal flu?

Answer 19

Occurs sporadically
Affects 25%+ of population
More serious, more complications

Question 20

How much of the population does seasonal flu usually affect?

Answer 20

10-15%

Question 21

What are pandemic requirements?

Answer 21

Human pathogenicity
‘New’ virus (antigenic shift)
Efficient person-to-person transmission

Question 22

Who is more susceptible to the flu?

Answer 22

Young and old

Question 23

How does avian flu spread?

Answer 23

Direct contact with infected birds: dead or alive
Occasional transmission via close human contact
Not food

Question 24

What are the clinical features of influenza?

Answer 24

Incubation period 2-4 days
Abrupt fever up to 41’ lasts 3 days
Plus 2 or more of: cough, sore throat, myalgia, headache, malaise
Predominance of systemic symptoms

Question 25

What are less common symptoms of influenza?

Answer 25

Nausea, vomiting, diarrhoea

Question 26

What is an ILI?

Answer 26

Influenza-like illness

Question 27

What is the WHO definition for an ILI?

Answer 27

Fever >38' AND cough onset with last 10 days

Question 28

What are the symptoms of swine flu?

Answer 28

Sudden fever Sudden cough Tiredness, chills Headache, sore throat, running nose, sneezine Diarrhoea, stomach upset, loss of appetite Aching muscles, limb or joint pain

Question 29

What is the transmission of influenza?

Answer 29

Airborne: Person -> person (droplets >5 microns) Contact: direct, indirect

Question 30

What is the period of virus shedding?

Answer 30

First 4 days of illness | Longer children+immunocompromised

Question 31

What is the virus survival?

Answer 31

24-48hrs non-porous surfaces | 8-12hrs porous surfaces (tissue)

Question 32

What are high risk groups for influenza?

Answer 32

``` Chronic organ disease DM Immunosuppression 65+ Pregnancy Children <6mo Morbid obesity ```

Question 33

What are common respiratory complications of influenza?

Answer 33

Acute bronchitis | Secondary bacterial pneumonia

Question 34

What are less common complications of influenza?

Answer 34

Resp: primary viral pneumonia Cardiac: myocarditis/pericarditis CNS: transverse myelitis/Guillain-Barre

Question 35

How does encephalitis lethargica present?

Answer 35

Fever, headache External ophthalmoplegia Lethargy Sleep reversal

Question 36

What are the investigations for influenza?

Answer 36

``` Viral nose and throat swabs Chest XR Blood culture Pulse oximetry RR U&Es, FBC< CRP ```

Question 37

When are patients at risk of secondary bacterial pneumonia and should have urgent CXR?

Answer 37

Flu symptoms and fever for >4 days

Question 38

What does the CURB65 score stand for?

Answer 38

``` Confusion Urea >7mmol/l RR BP >65 ```

Question 39

What class of drugs are commonly used for influenza?

Answer 39

Neuraminidase inhibitors | antiviral therapy

Question 40

What are examples of neuraminidase inhibitors?

Answer 40

Zanamivir | Oseltamivir (Tamiflu)

Question 41

What is the common name for oseltamivir?

Answer 41

Tamiflu

Question 42

What is the management for influenza?

Answer 42

Antiviral therapy - Tamiflu or Relenza

Question 43

What are the common ADR for Tamiflu?

Answer 43

Nausea, vomiting, abode pain, diarrhoea

Question 44

What is the first line therapy in a pregnancy influenza?

Answer 44

Tamiflu

Question 45

When does an individual become non-infectious with influenza?

Answer 45

24hrs after last flu symptoms or when anti-viral therapy completed