Influenza

Question 1

What are the classifications of influenza virus?

Answer 1

Influenza A - Mammals & Birds

Influenza B - Humans

Influenza C - Humans

Question 2

What is the Influenza virus?

Answer 2

• RNA virus
• 8 segment Genome
• Part of Orthomyxoviridae family

Question 3

What Influenza virus’ are the most common?

Answer 3

A & B

Question 4

What is antigenic shift?

Answer 4

• An abrupt major change in the virus, resulting in new Haemagglutinin/Neuraminidase combinations
• Antigenic shift results in a genetic change that enables a flu strain to jump from one animal species to another
• The process of antigenic shift involves 2 or more different strains of a virus combining to form a new subtype, resulting in new H/N combinations
• Antigenic shift involves the reassortment of the virus’ gene segments
• Drastic change

Question 5

What is antigenic drift?

Answer 5

• The mechanism of genetic variation within the virus
• Occurs continually over time, with small on-going point mutations in genes coding for antibody binding sites
• Overtime the antigenic properties may change and eventually the immune system will not be able to combat the virus as well
• Subtle change

Question 6

What is the epidemiology of seasonal influenza (flu)?

Answer 6

• Occurs every winter
• Affects 10-15% of population
• Unpleasant but not life-threatening

Question 7

What is the epidemiology of pandemic influenza (flu)?

Answer 7

• Occurs sporadically
• Affects 25% + of population
• More serious, more complications

Question 8

What is the difference between an epidemic and a pandemic?

Answer 8

Epidemic - An outbreak of a disease that affects large numbers of a population in certain communities

Pandemic - An outbreak of a disease that spreads throughout the world

Question 9

How is Influenza diagnosed in the lab?

Answer 9

• Molecular detection from nose & throat swabs
• Polymerase chain reaction (PCR)
• Blood viral cultures

Question 10

What is the presentation of influenza in the community?

Answer 10

• Abrupt fever (around 38-40 degrees) which lasts 3 days
• Cough
• Myalgia
• Headache
• Malaise

Question 11

If the patient with flu requires hospitalization, what is the condition called?

Answer 11

Severe Acute Respiratory Infection (SARI)

Question 12

What are the possible complications of influenza?

Answer 12

Respiratory:

• Acute Bronchitis
• Secondary Bacterial Pneumonia

Question 13

What are the most common bacteria found in influenza associated secondary bacterial pneumonia?

Answer 13

1 - Streptococcus Pneumoniae (48%)

2 - Staphylococcus Aureus (26%)

3 - H.Influenza (11%)

Question 14

What role can antiviral agents have in the treatment of influenza?

Answer 14

• Antivirals should be used within 48 hours of influenza symptom onset
• The patients condition (healthy, at risk group, complicated or uncomcomplicated influenza) should be taken into account when deciding on the antiviral to use

Question 15

What is the commonly used antiviral drug used in the uncomplicated influenza patients who are not severely immunosuppressed?

Answer 15

Oseltamivir

Question 16

What are the treatment options for patients with influenza and suffering with complications?

Answer 16

1st line - Oseltamivir

2nd line - Zanamivir

Question 17

What is the role of immunisation in preventing outbreaks of influenza?

Answer 17

• Seasonal flu vaccine, which contains chemically inactivated viruses considered most likely to be circulating in the forthcoming winter
• Being immunised can help reduce the risk to the ‘at risk’ patients

Question 18

What antiviral therapies are used during pregnancy?

Answer 18

• Oseltamivir
• Zanamivir