Influenza

Question 1

When are the influenza months?

Answer 1

Dec - Feb (North)

Jun - Aug (South)

Question 2

When do more severe influenza epidemics take place?

Answer 2

Every 11 years - sunspots

Question 3

What type of virus is influenza?

Answer 3

RNA virus - Orthomyxoviridae

A, B, C

Question 4

Which influenza groups affect humans?

Answer 4

IfB

IfC

Question 5

Which influenza surface proteins affect humans?

Answer 5

Haemagglutinin (H) 18 types

Neuraminidase (N) 11 types

Question 6

What is the role of Haemagglutinin?

Answer 6

Facilitates viral attachment and host cell entry

Question 7

What is the role of Neuraminidase?

Answer 7

Enables new virion to be released from the host cell

Question 8

What is antigenic drift?

Answer 8

Small, on-going point mutations in the genes coding for antibody binding-sites

Question 9

What is the effect of antigenic drift?

Answer 9

Change the antigenic properties, so immune system cant combat it
(reduces immunity/vaccine effectiveness)

Question 10

What is antigenic shift?

Answer 10

Abrupt change in virus - new H/N combinations

2 or more strains combine to form new subtype

Question 11

What is the effect of antigenic shift?

Answer 11

Jumping from species - species
Can combine to form
Reassortment of virus gene segments
Can lead to pandemics

Question 12

What virus was implicated in the 2009/10 pandemic?

Answer 12

H1N1

Question 13

How does pandemic flu differ from seasonal flu?

Answer 13

Pandemic:
Sporadic
25%+ population
More serious

Seasonal:
Every winter
10-15% population
Unpleasant

Question 14

What are the requires for a pandemic?

Answer 14

Human pathogenicity
Antigenic shift = susceptible population
Efficient person-person transmission

Question 15

Which Avian flu strains effect humans?

Answer 15

H5N1

H7N9

Question 16

How is Avian flu spread?

Answer 16

Direct contact with infected birds

Human-human

Question 17

What is the fatality rate of Avian flu?

Answer 17

H5N1 - 60%

H7N9 - 36%

Question 18

Where is avian flu still present?

Answer 18

H5N1 - Egypt

H7N9 - China

Question 19

What are the clinical features of influenza?

Answer 19

2-4 day incubation
Abrupt 41C fever 3 days
2 or more of:
Cough
Sore throat
Myalgia
Headache
Malaise

Question 20

What is Influenza-like illness?

Answer 20

Fever >38C AND
Cough
Onset within last days

Question 21

How is influenza transmitted?

Answer 21

Airborne - droplets >5um

Contact

Question 22

What is virus shedding?

Answer 22

First 4 days of illness

longer in children/immunocompromised

Question 23

How long is virus survival?

Answer 23

24-48hrs on non-porous surfaces

8-12hrs on porous surfaces

Question 24

What are the risk factors for complicated influenza?

Answer 24

Neurological, hepatic, renal, pulmonary and chronic cardiac disease
Diabetes mellitus
Severe immunosuppression
Age over 65 years
Pregnancy (+ up to two weeks post partum)
Children under 6 months of age
Morbid obesity (BMI ≥40)

Question 25

What are the common complications of influenza?

Answer 25

Acute Bronchitis | Secondary bacterial pneumonia

Question 26

How does Secondary bacterial pneumonia present?

Answer 26

4-5 days post-flu S. pneumoniae Staph aureus H. influenzae

Question 27

What are the less common respiratory complications of influenza?

Answer 27

Primary viral pneumonia

Question 28

What are the less common cardiac complications of influenza?

Answer 28

Myocarditis/pericarditis

Question 29

What are the less common CNS complications of influenza?

Answer 29

Transverse myelitis/Guillain-Barre | Myositis & Myoglobulinaemia

Question 30

How does primary viral pneumonia present?

Answer 30

Common in H5N1 Rapid respiratory failure (48hrs) Mortality >40%

Question 31

What is encephalitis lethargica?

Answer 31

Post-influenza sequelae

Question 32

How does encephalitis lethargica present?

Answer 32

``` Fever Headache External ophthalmoplegia Lethargy Sleep reversal Postencephalitic Parkinsonism 25% mortality ```

Question 33

How is influenza diagnosed?

Answer 33

``` Viral nose/throat swabs PCR Chest x-ray (pneumonitis/ia) Blood culture Pulse oximetry Respiratory rate U+E, FBC, CRP ```

Question 34

What is the function of CRP monitoring in influenza?

Answer 34

Monitoring pneumonia recovery | CRP should halve in 4 days

Question 35

When is an urgent CXR indicated in pneumonia?

Answer 35

Flu like symptoms and fever for >4 days

Question 36

Which severity assessment is used for pneumonia?

Answer 36

CURB-65

Question 37

What does CURB65 stand for?

Answer 37

``` Confusion Urea (>7mmol/l) Resp rate (>30) Blood pressure (<90sys, <60dia) >65y/o ```

Question 38

Which medications are used for influenza?

Answer 38

Neuraminidase Inhibitors (antivirals) Within 48hrs Oseltamivir (Tamiflu) Zanamivir (Relenza)

Question 39

Which medications are used for influenza? (Hard)

Answer 39

``` Neuraminidase Inhibitors within 48hrs Oseltamivir (Tamiflu) Dose - 75mg every 12hrs 5 days Zanamivir (Relenza) Dose - 10mg inhaled daily up to 10 days ```

Question 40

What side effects are associated with Oseltamivir?

Answer 40

``` Nausea + Vomiting Abdominal pain Diarrhoea Headache Caution in renal failure ```

Question 41

How is complicated influenza managed?

Answer 41

Oseltamivir (oral) | Zanamivir if resistant/poor response

Question 42

What are the less commonly used antivirals in influenza?

Answer 42

Peramivir - IV (uncomplicated) Flavipiravir - oral Baloxavir Marboxil

Question 43

How is antiviral therapy managed in pregnancy?

Answer 43

Oseltamivir

Question 44

How is antiviral therapy managed in breastfeeding?

Answer 44

Oral Oseltamivir

Question 45

When does an individual become non-infectious?

Answer 45

24hrs after last symptoms or When anti-viral therapy is completed (in immunocompetent adult)

Question 46

How can healthcare staff protect themselves from flu in patients on nebuliser/NIV?

Answer 46

Face fit respirator mask