Influenza

Question 1

What is the influenza virus?

Answer 1

RNA virus, 3 main groups - A (infects mammals and birds), B and C infect humans

Question 2

What is antigenic drift?

Answer 2

Mechanism of genetic variation within the virus. Occurs over time and may change antigenic properties and eventually, the immune system will not combat virus as well

Question 3

What is antigenic shift?

Answer 3

Abrupt major change in virus resulting in new H/N combinations i.e a reassortment of virus gene segments

Question 4

What are the differences between pandemic and seasonal flu?

Answer 4

Seasonal - occurs every winter, affects 10-15% of population, usually unpleasant but not life threatening

Pandemic Flu - Occur sporadically, Affects 25% of population, More serious and more complications

Question 5

What are the requirements for a pandemic?

Answer 5

Human pathogenicity, new virus present and efficient person-person transmission

Question 6

What is avian flu?

Answer 6

Virus of influenza which spreads through direct contact with infected birds, dead or alive. Occasional transmission via close human to human contact

Question 7

What are the clinical features of influenza?

Answer 7

Incubation period of 2-4 days, abrupt fever up to 41 degrees which lasts 3 days, plus 2 more of cough, myalgia, headache, malaise

Question 8

How is influenza transmitted?

Answer 8

Airborne: person -> person by large droplets

Direct contact from person to person

Indirect contact from person to formite to person

Question 9

What groups of people are at high risk for complicated influenza?

Answer 9

Neurological, hepatic, renal, pulmonary and chronic cardiac disease
Those with diabetes
Severe immunosuppression
Aged over 65
Pregnant women
Children under 6 months 
Morbid obesity

Question 10

What are common complications of influenza?

Answer 10

Acute bronchitis, secondary bacterial pneumonia

Question 11

What is encephalitis lethargica ?

Answer 11

Fever, headache, external opthalmoplegia, lethargy, sleep reversal

Question 12

What are the investigations for influenza?

Answer 12

Viral nose and throat swabs, CXR, Blood culture, pulse oximetry, resp rate, UE’s, FBC, CRP

Question 13

What treatment should be given?

Answer 13

Tamiflu, relenza, alpivab, avigan, xofluza

Question 14

When are immunocompetent patients non-infectious?

Answer 14

24hours after last flu symptoms or when anti-viral therapy is completed

Question 15

What protective measures must be taken for those coming into contact with flu patients?

Answer 15

Surgical face mask, plastic apron, gloves

Question 16

What is the seasonal flu vaccine?

Answer 16

Vaccines prepared using viruses considered most likely to be circulating in the forthcoming winter. Grown in chick embryos and is therefore not suitable for those with an egg allergy