Influenza

Question 1

Describe the structure of the Flu Virus

Answer 1

Enveloped orthomyxovirus that contains a negative single stranded RNA genome divides into eight segments

Question 2

Influenza A infects

Answer 2

Mammals

Question 3

Influenza B an C infect

Answer 3

Only humans

Question 4

State the two different surface proteins present on the Influenza Virus

Answer 4

Haemagglutin and Neuraminidase

Question 5

State the function of Haemaglutin

Answer 5

Facilitates viral attachment and entry to the host cell

Question 6

State the function of neuraminidase

Answer 6

Enables new virion to be released from the host cell

Question 7

Why are annual epidemics of flu possible

Answer 7

Due to the antigenic drift meaning that there are a sufficiently large number of individuals without immunity for the virus to circulate and in some years for a epidemics to occur.

Question 8

What is antigenic drift

Answer 8

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

Question 9

What is antigenic shift

Answer 9

Abrupt major change in the virus, resulting in new H/N combinations being made. This is what enables a flu strain to jump from one species to another.

Question 10

What is the consequence of antigenic shift

Answer 10

Pandemics

Question 11

What is different about a pandemic flu

Answer 11

They occur sporadically, affect 25% of the population and are more serious with more complications

Question 12

State the requirements for a flu virus being pandemic

Answer 12

Human pathogenicity, New virus, efficient person-person transmission

Question 13

State the two strains of avian flu which can effect humans

Answer 13

H5N1, H7N9

Question 14

How is avian flu spread

Answer 14

Direct contact with infected birds, dead or alive

Question 15

State the fatality rate of H5N1

Answer 15

60%

Question 16

State the fatality rate of H7N9

Answer 16

36%

Question 17

State the incubation period of influenza

Answer 17

2-4 days

Question 18

State the symptoms of influenza

Answer 18

Abrupt fever which lasts around 3 days, cough, sore throat, rhinorrhoea, myalgia, headache, malaise sometimes nausea, vomiting, diarrhoea

Question 19

How is influenza trasmitted

Answer 19

Airborne (large droplets), direct contact or indirect contact

Question 20

Virus shedding for influenza occurs

Answer 20

First 4 days of illness

Question 21

How long can the virus survive on non-porous surfaces

Answer 21

24-48 hours

Question 22

State the respiratory complications of influenza

Answer 22

Acute bronchitis, secondary bacterial pneumonia

Question 23

When does secondary bacterial pneumonia tend to occur

Answer 23

4-5 days after the start of the flu

Question 24

In which virus does primary viral pneumonia tend to occur

Answer 24

H5N1

Question 25

What are the symptoms of primary virual pneumonia

Answer 25

Rapid respiratory failure

Question 26

State the mortality rate of primary viral pneumonia

Answer 26

40%

Question 27

State the CVS complications of influenza

Answer 27

Myocarditis/pericarditis

Question 28

State the CNS complications of influenza

Answer 28

Transverse myelitis, myositis and myoglobinuria

Question 29

State the symptoms of encephalitis Lethargica

Answer 29

Fever, headache, external ophthalmoplegia, lethargy, sleep reversal

Question 30

State the link between encephalitis lethargica and influenza

Answer 30

Influenza A found in serology of patients

Question 31

State the mortality of encephalitis lethargica

Answer 31

25%

Question 32

How is Influenza diagnosed

Answer 32

Usually clinical diagnosis, viral nose and throat swabs, chest Xray if concerned about pneumonia, blood culture, respiratory rate, U and E, Creatinine, FBC

Question 33

When should patients have an urgent CXRAY to look for secondary bacterial pneumonia

Answer 33

If they have flu symptoms and fever for more than 4 days

Question 34

How can influenza be treated

Answer 34

Neuraminidase inhibitors like zanamivir and oseltamivir

Question 35

When should patients with influenza be treated with neuraminidase inhibitors

Answer 35

Patients at risk of severe complications

Question 36

When should neuraminidase inhibitors be given to be most effective

Answer 36

Within 48 hours of onset

Question 37

State the dose of oseltamivir (tamiflu)

Answer 37

75mg every 12hours for 5 days

Question 38

State the common side effects of tamiflu

Answer 38

Nausea, vomiting, abdominal pain and diarrhoea. Others include, hallucinations, insomnia and rash

Question 39

State the dose of zanamivir

Answer 39

10mg inhaled daily for up to 10 days

Question 40

Which strains are resistant to oseltamavir

Answer 40

H1N1

Question 41

When does an immunocompetent adult become non-infectious

Answer 41

24 hours after last flu symptoms

Question 42

Where is the seasonal flu vaccine grown

Answer 42

Allantoic cavity of chick embryos

Question 43

What does the influenza virus contain

Answer 43

2 type A and 1 type B subtype