Influenza

Question 1

What kind of virus is influenza?

Answer 1

RNA virus

Question 2

3 main groups of influenza

Answer 2

A
B
C

Question 3

What does IfA affect?

Answer 3

Mammals

Birds

Question 4

What do IfB and IfC affect?

Answer 4

only humans

Question 5

Surface proteins of influenza

Answer 5

18 different H antigens (H1-3 in humans) = haemagglutinin (H)
11 different N antigens = Neuraminidase (N)

Question 6

What does haemagglutinin allow?

Answer 6

Viral attachment and entry into the host cell

Question 7

What do neuraminidases allow?

Answer 7

Enables new virion to be released from host cell

Question 8

What is antigenic drift?

Answer 8

Mechanism of genetic variation within the virus

Question 9

What can antigenic drift cause?

Answer 9

Worse than normal epidemics

Vaccine mismatch

Question 10

Definition of pandemic

Answer 10

Virus spreads across the whole globe

Question 11

When does pandemic flu occur?

Answer 11

Sporadically - not in usual influenza months

Question 12

Mortality with pandemics increases with….

Answer 12

age

Question 13

What strains of avian flu affect humans?

Answer 13

H5N1

H7N9

Question 14

Transmission of avian flu

Answer 14

Spreads through direct contact with infected birds, dead or alive
Occassional transmission via close human to human contact (staff, caregivers)

Question 15

Which avian flu strain has the highest mortality in humans?

Answer 15

H5N1

Question 16

Investigations for influenza

Answer 16

Viral nose and throat swabs/VTs (molecular detection/PCR; using flocked swabs)
CXR; pneumonitis/pneumonia/ARDs
Blood culture
Pulse oximetry; SpO2 < 92% need ABG + oxygen
Respiratory rate
U and Es, FBC, CRP

Question 17

Incubation period of influenza

Answer 17

2-4 days (range 1-7 days)

Question 18

Presentation of influenza

Answer 18

Abrupt fever up to 41C (commonly 38-41) which lasts 3 days (range 1-5 days)
2 or more of
- cough 
- sore throat, rhinorrhoea
- myalgia
- headache
- malaise 
Predominance of systemic symptoms
Less common symptoms
- nausea 
- vomiting
- diarrhoea

Question 19

Definition of influenza like illness (ILI)

Answer 19

Fever >38C AND cough with onset in last 10 days

Question 20

If influenza illness requires hospitalisation, what is it classed as?

Answer 20

Severe acute respiratory infection (SARI)

Question 21

Symptoms of swine flu

Answer 21

Sudden fever (>38C)
Sudden cough 
tiredness
chills
headache
sore throat, runny nose, sneezing
Diarrhoea, loss of appetite
Aching muscles, joint or limb pain

Question 22

Transmission of influenza

Answer 22

Airborne 
- person to person by large droplets
Contact
- direct (person to person)
- indirect (person to fomite to person)

Question 23

When does virus shedding of influenza occur?

Answer 23

First 4 days of illness (range 1-7 days)

Question 24

Viral survival of influenza

Answer 24

24-48 hours on non-porous surfaces

8-12 hours on porous surfaces e.g. tissue

Question 25

Risk factors for complicated influenza

Answer 25

``` Neurological, hepatic, renal, pulmonary and chronic cardiac disease Diabetes mellitus Severe immunosuppression Age > 65 Pregnancy and up to 2 weeks post partum Children < 6 months old Morbid obesity (BMI >_40) ```

Question 26

Complications of influenza

Answer 26

``` Acute bronchitis Secondary bacterial pneumonia (20%) - 4-5 days before the start of the flu Community MRSA uncommon in US/Europe less common - primary viral pneumonia - myocarditis/pericarditis - CNS e.g. Guillian barre ```

Question 27

Presentation of encephalitis lethargia

Answer 27

``` fever headache external opthalmoplegia lethargy sleep reversal ```

Question 28

Mortality of encephalitis lethargia

Answer 28

25%

Question 29

Complications of encephalitis lethargia

Answer 29

Postencephalitic parkinsonism

Question 30

When does an individual become non-infectious in immunocompetent adults?

Answer 30

Whichever one of the below lasts longer - 24 hrs after last flu symptoms (fever and cough) OR - When antiviral therapy is completed

Question 31

When should antiviral therapy be given in the treatment of influenza?

Answer 31

ASAP and within 48 hours of symptom onset | In complicated illness - should always be given, not matter how long after onset of illness

Question 32

Antivirals that can be used to treat influenza

Answer 32

Oseltamivir (Tamiflu) - FIRST LINE Zanamivir (Relenza) - SECOND LINE Peramivir Favipiravir

Question 33

Can oseltamivir be used in pregnancy for the treatment of influenza?

Answer 33

Yes

Question 34

What must be worn by healthcare professionals if patient has proven or suspected flu?

Answer 34

Surgical face mask Plastic apron Gloves

Question 35

Who is the seasonal flu vaccine contraindicated to and why?

Answer 35

Those with an egg allergy as the vaccine is grown in the allantoic cavity of chick embryos

Question 36

What do seasonal flu vaccines contain?

Answer 36

They are trivalent - 2 type A subtype viruses - 1 type B subtype viruses

Question 37

Why should healthcare workers have the flu vaccine?

Answer 37

To protect themselves and their families To reduce the risk to 'at risk' patients To reduce absence from work during influenza 'surge' activity