Influenza

Question 1

What is it?

Answer 1

Influenza infection is characterised by upper and lower respiratory tract symptoms of rhinorrhoea, cough, fever, chills, headache, and myalgia.

Question 2

What type of virus is it?

Answer 2

ssRNA virus

Question 3

What are the different types and which ones undergo antigenic shift and drift?

Answer 3

Three types:A,BandC, of which A and B are the most common

• All undergo antigenic drift
• Influenzae A undergoes antigenic shift

Question 4

What is antigenic drift? what does this mean with vaccination?

Answer 4

Minor changes in the genes (H and N protein) of flu viruses that occur gradually overtime - seasonal epidemics

New vaccination yearly

Question 5

What is antigenic shift?

Answer 5

Major changes in the genes of the flu virus that occur when 2 or more different strains combine -forms new subtype
Causes widespread epidemics/pandemics

Question 6

How does it spread?

Answer 6

Spreads via small particles, aerosols, larger particles and droplets or land on surfaces remain infectious

Question 7

What does H protein do?

Answer 7

• H protein (Haemagglutinin)- binds to cell of infected person via sialic acid on cell receptors
  
  • allows virus to enter via receptor mediated endocytosis

Question 8

What does N protein do?

Answer 8

N protein (Neuraminidase)- release virus from host cell

Question 9

Human barriers againt resp infections

Answer 9

• Thick glycocalyx on resp epithelial cells and tracheobronchial mucus that can trap virus particles
  
  • Mucociliary escalator removes particles caught in mucus
  • Immunologic defences like secretory IgA, NK cells and macrophages

Question 10

Symptoms

Answer 10

• Fever
• Rhinitis - rhinorrhoea
• Lethargy and fatigue
• Anorexia (loss of appetite)
• Muscle and joint aches- myalgia
• Headache
• Dry cough
• Sore throat

Question 11

Investigations ?

Answer 11

Treatment is usually started based on the history, risk factors and clinical presentation.

Viral nasal or throat swabs- PCR Analysis

Antigen test

Question 12

How is it treated in most cases?

Answer 12

Resolve itself with self-care measures- adequate fluid intake and rest
Analgesia and anti-pyretic

Question 13

What do public health do ?

Answer 13

monitor the number of cases of flu and provide guidance on when there is enough flu in the area to justify treating patients with suspected flu

Question 14

If pt has risk of complications what do we give as treatment ? in what time period?

Answer 14

Treatment needs to be started≤ 48 hours
of the onset of symptoms to be effective

• Oraloseltamivir75mg twice daily for 5 days
• Inhaledzanamivir10mg twice daily for 5 days

Question 15

Whos the vaccine given to for free on NHS?

Answer 15

• Aged 65
• Young children
• Pregnant women
• Chronic health conditions such as asthma, COPD, heart failure and diabetes
• Healthcare workers and carers

Question 16

some complications?

Answer 16

• Otitis media, sinusitis and bronchitis
• Viral pneumonia
• Secondary bacteria pneumonia
• Worsening of chronic health conditions such as COPD and heart failure
• Febrile convulsions (young children)
• Encephalitis/ meningitis
• pericarditis/myocarditis