Influenza

Question 1

Where does the name influenza come from?

Answer 1

‘influentia’ – meaning influence of the stars

Question 2

When does seasonal influenza occur?

Answer 2

Dec – Feb in the Northern Hemisphere Jun – Aug in the Southern Hemisphere

Question 3

How often does more severe episodes of influenza occur?

Answer 3

More severe epidemics of influenza occur every 11 years

Question 4

What is a pandemic?

Answer 4

When the virus spreads across the whole globe

Question 5

What was the most severe outbreak of influenza?

Answer 5

1918-9 ‘Spanish Flu’

Question 6

When was the most recent severe pandemic?

Answer 6

2009/10 - Swine Flu

Question 7

What are the three main types of influenza and who do they affect?

Answer 7

A (1933) - affects mammals and birds B (1939) - humans C (1950) - humans

Question 8

What is the role of surface proteins?

Answer 8

Surface proteins is what meds target and what creates a new strain of virus

Question 9

What is the H antigen and action?

Answer 9

Haemagglutinin (H) - facilitates viral attachment and entry to host cell

Question 10

What is the N antigen and action?

Answer 10

Neuraminidase (N) - enables new virion to be released from host cell

Question 11

Which H antigens label a human virus?

Answer 11

H1 - 3

Question 12

What is antigenic drift?

Answer 12

• Mechanism of variation within the virus. - Occurs continually over time, small on-going point mutations in the genes coding for antibody binding-sites

Question 13

What are the implications of drift?

Answer 13

Change the antigenic properties and eventually the immune system will not combat the virus as well Causes worse than normal epidemics & vaccine mismatch [every year WHO try to match these mutant viruses attempting to create vaccines]

Question 14

What is antigenic shift?

Answer 14

Abrupt major change in the virus, resulting in new H/N combinations - process by which two or more different strains of a virus combine to form a new subtype, resulting in new H/N combinations

Question 15

What are the implications of shift?

Answer 15

The genetic change that enables a flu strain to jump from one animal species to another

Question 16

How quickly can a influenza virus spread?

Answer 16

3 days to spread from 4 countries to worldwide

Question 17

What is the differences between seasonal flu and pandemic flu?

Answer 17

Seasonal flu: - every winter - 10-15% of population - unpleasant but not life threatening Pandemic flu: - occurs sporadically - affects 25% of population - more serious, can be life threatening

Question 18

What are requirements for the occurrence of a pandemic?

Answer 18

• human pathogenicity - ‘new’ virus (antigenic shift) - Efficient person-person transmission

Question 19

What is the wave phenomenon of pandemics?

Answer 19

it occurs sporadically (on a graph looks like a wave)

Question 20

What is notable about the age of mortality in pandemics versus seasonal flu?

Answer 20

• seasonal flu effects young and old most severely - pandemic flu effects the middle age group more severely

Question 21

How does avian flu spread?

Answer 21

Spreads through direct contact with infected birds, dead or alive

Question 22

What is the fatality rate of avian flu?

Answer 22

High case fatality rate: 60% (H5N1), 36% (H7N9)

Question 23

What is the incubation period of infuenza?

Answer 23

2-4 days

Question 24

What is the most common presentation? What are the main additional features?

Answer 24

*abrupt fever up to 41 degrees lasting up to 3 days* + 2 or more of: cough, sore throat, myalgia, headache, malaise

Question 25

What is influenza like illness?

Answer 25

Fever (>38°C) and Cough Onset within the last 10 days

Question 26

What are the main modes of transmission of influenza?

Answer 26

Airborne: person to person by large droplets >5 microns Contact: direct, indirect

Question 27

What is virus shedding?

Answer 27

Expulsion and release of virus progeny following successful reproduction during a host-cell infection

Question 28

What is the timeline of virus shedding?

Answer 28

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

Question 29

What are the RF for complicated influenza?

Answer 29

a. 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 30

What are common complications of influenza?

Answer 30

Acute bronchitis Secondary bacterial pneumonia [20%, will occur 4-5 days after of flu]

Question 31

How can we investigate influenza?

Answer 31

Viral nose and throat swabs Chest X-ray Blood culture Pulse oximetry Resp rate

Question 32

What is the definition of secondary bacterial pneumonia?

Answer 32

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

Question 33

How do we access the severity of secondary bacterial pneumonia?

Answer 33

CURB 65 - Confusion - Urea >7mmol - Resp rate >30mm - BP (diastolic <60 or systolic <90) - Over 65 age C(U)RB score: Risk of death in the next 30 days (0=0.6%, 1=3.2%, 2=13%, 3=17%, 4=41.5%, 5=57%)

Question 34

When and what antivirals are used in therapy for influenza?

Answer 34

Use ASAP and within 48hrs of symptom onset - Oseltamavir (oral) - Zanamivir (inhaled)

Question 35

What are the guidelines for antiviral therapy in pregnancy/breastfeeding?

Answer 35

Preggers: Antivirals have been recommended…due to the adverse outcomes …in this group Oseltamivir remains first line option Breastfeeding: Only tiny amounts of Oseltamivir in milk Current guidance is – Oral Oseltamivir

Question 36

What protection is implemented for healthcare staff when there is flu risk?

Answer 36

Surgical face mask Plastic apron Gloves Wash hands after any examination