Influenza

Question 1

What is influenza?

Answer 1

Acute respiratory tract infection typically caused by seasonal influenza A or B virus.
- The virus is transmitted by inhalation of infected respiratory secretions that have been aerosolised through coughing, sneezing, or talking 

Question 2

What causes influenza?

Answer 2

• Seasonal influenza virus is a member of the orthomyxovirus family.
• It has a segmented, single-stranded RNA genome that can be classified into influenza A, B, and C based on antigenic differences. 
• RNA virus of the family orthomyxoviruses spread via person-to-person transmission directly via respiratory droplets or indirectly through contact with contaminated surfaces

Question 3

What are the presenting symptoms of influenza?

Answer 3

• Sore throat 
• Fever 
• Dry cough 
• Coryzal symptoms 
• Headache 
• Malaise 
• Myalgia 
• Conjunctivitis, eye pain ± photophobia 

Question 4

What are the risk factors for influenza?

Answer 4

• Age ≥ 65 y/o
• Age 6-59 months
• Chronic cardiovascular or resp conditions
• Diabetes
• Haemoglobinopathy
• Immunocompromise
• CKD
• pregnancy
• carers and household contacts of high risk groups
• healthcare workers

Question 5

What investigations are used to diagnose/ monitor influenza?

Answer 5

1. Clinical diagnosis 
2. Viral culture 
3. Direct immunofluorescent antibody staining 
4. Reverse transcriptase-polymerase chain reaction 
5. Serology 
6. Enzyme immunoassay (EIA) 
7. Rapid diagnostic tests 
8. CXR 

Question 6

How is influenza managed?

Answer 6

1. Supportive Care → analgesia, antipyretics, fluids, oxygen
2. Antiviral Therapy → neuraminidase inhibitors (inhibits release of virus from host cells) = oseltamivir (’tamiflu’) or zanamivir
3. Influenza Vaccination → inactivated vaccine tailored each year according to recent outbreaks. Recommended for certain groups (eg. >65s, healthcare workers, those with chronic conditions).
   - Shouldn’t be given to acutely unwell patients (wait until recovered)
4. Broad-Spectrum Antibiotic Therapy (ceftriaxone) → if complication of bacterial pneumonia

Question 7

What complications may arise from influenza?

Answer 7

bacterial pneumonia, otitis media, encephalitis