Influenza

Question 1

What is the INFLUENZA VIRUS structure

Answer 1

RNA virus. 8 segment genome

Question 2

IfA infects mammals and birds, IfB & IfC only …

Answer 2

Humans

Question 3

Haemagglutinin (H) allows

Answer 3

viral attachment and entry to host cell

Question 4

Neuraminidase (N) allows

Answer 4

new virion to be released from host cell

Question 5

ANTIGENIC DRIFT

Answer 5

Mechanism of genetic variation within the virus

Question 6

pandemics flu occur

Answer 6

three times each century and can arise at any time of the year

Question 7

PANDEMIC REQUIREMENTS (3)

Answer 7

Human pathogenicity

‘New’ virus (antigenic shift)
- susceptible population

 Efficient person-person
transmission

Question 8

AVIAN FLU - features

Answer 8

Spreads through direct contact with infected birds, dead or alive

• COULD SPREAD via close human contact

Question 9

Clinical features of influenza (4)

Answer 9

Abrupt fever up to 41°C (commonly 38-40°C) which lasts 3 days (range 1-5 days)

Plus 2 or more of: Cough, [sore throat, rhinorrhoea], myalgia, headache, malaise.

Predominance of systemic symptoms

Less common symptoms: Nausea, vomiting, diarrhoea

-

Question 10

if requires hospitalization defined as ?

Answer 10

severe acute respiratory infection (SARI)

Question 11

Symptoms of swine flu

Answer 11

sudden fever nd sudden cough

tiredness, chills, headache, sneezing, diarrhoea, aching muscles

Question 12

Transmission of swine flu

Answer 12

Airborne – person  person by large droplets >5 microns
Contact – direct (person  person)
– indirect (person  fomite  person)

Question 13

Virus shedding occurs

Answer 13

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

Longer in young children & immunocompromised

Question 14

Virus survival occurs

Answer 14

24-48 hours on non-porous surfaces

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

Question 15

HIGH RISK GROUPS - risk factors for complicated influenza

Answer 15

Neurological, hepatic, renal, pulmonary and chronic cardiac disease

b. Diabetes mellitus
c. Severe immunosuppression
d. Age over 65 years
e. Pregnancy (including up to two weeks post partum)
f. Children under 6 months of age
g. Morbid obesity (BMI ≥40)

Question 16

Common respiratory complications

Answer 16

Acute Bronchitis

Secondary Bacterial Pneumonia (~20%)
Appears 4-5 days after start of ‘flu

Question 17

Organisms seen in microbiology for common respiratory complications

Answer 17

H.influenza, S.pneumoniae, βhaem.strept

Staph.aureus (>2/3rds)

Question 18

Less Common Complications, respiratory, cardiac and CNS

Answer 18

Primary viral pneumonia

Myocarditis/pericarditis

Transverse myelitis/Guillain-Barre
Myositis & Myoglobinuria

Question 19

ENCEPHALITIS LETHARGICA

Answer 19

Fever, headache
External ophthalmoplegia
Lethargy
Sleep reversal

Question 20

DIAGNOSIS & INVESTIGATIONS - (6)

Answer 20

Viral nose and throat swabs/VTS (Molecular detection /PCR; using flocked swabs)
Chest X-ray – pneumonitis/pneumonia/ARDS
Blood culture
Pulse oximetry – SpO2 <92% need ABG and oxygen
Respiratory rate !
U & E’s, FBC, CRP (CRP monitoring recovery of pneumonia - should halve in 4 days)

Question 21

SECONDARY BACTERIAL PNEUMONIA

Answer 21

Patients with ‘flu symptoms and a fever for > 4days – should have an urgent CXR

Question 22

The severity assessment

Answer 22

C(U)RB-65 score
Confusion
Urea >7mmol/l
Respiratory rate >30mm
Blood Pressure (diastolic <60 or systolic <90)
>65 years of age

Question 23

What should you use ASAP

Answer 23

ANTIVIRAL THERAPY

ZANAMIVIR (RELENZA) – Inhaled & or I.V.

OSELTAMVIR

Question 24

Other antiviral therapy

Answer 24

Peramivir (Alpivab®) - IV

Favipiravir (Avigan) - ORAL

Baloxavir Marboxil - one dose

Amantadine & Rimantadine

Question 25

When does an individual become non-infectious

Answer 25

UNOCOMPETENT ADULTS

24hrs after last flu symptoms (fever & cough)
Or when anti-viral therapy completed
Which ever is longer

Question 26

vaccination?

Answer 26

Seasonal flu vaccine