Viral Respiratory Tract Infection

Question 1

Which viruses cause the common cold?

Answer 1

• Rhinoviruses (80%)
• Coronaviruses (20%)

Question 2

Which viruses cause croup?

Answer 2

• Parainfluenza viruses 1-4

Question 3

Which viruses cause influenza?

Answer 3

• Most commonly caused by influenza virus which is an orthomyxocirus of which there are 3 types (A-C)
• RNA virus

Question 4

Which ciruses cause bronchiolitis?

Answer 4

• Respiratory Syncitial Virus (RSV) which is a paramyxovirus - ssRNA

Question 5

What are the clinical features of bronchiolitis?

Answer 5

• Indlammation of the bronchioles which become infected and plugged with mucus
• Presents like a common cold (sore throat, blocked nose, fatigue) but with cough, wheeze and difficulty breathing

Question 6

What are the clinical features of influenza?

Answer 6

• High fever
• Chills
• Headaches
• Loss of appetite
• Mood swings
• Cough (with sputum/phlegm)
• SOB
• Pleuritic chest pain
• Clamminess
• Blueness of skin
• Low BP
• High HR
• Joint pain
• Fatigue
• Aches
• Haemoptysis

Question 7

How can viral RTIs be treated?

Answer 7

• Croup is supportive
• Bronchiolitis involves Ribivirin in severe cases
• Influenza can be treated with Neuraminidase inhibitors (prevent release of the virus from infected cells)

Question 8

What is antigenic drift?

Answer 8

• Gradual change in proteins (through mutations) so that our immune systems no longer recognise them

Question 9

What are the three mechanisms of antigenic shift?

Answer 9

• Influenza strain passed to immediate host and can jump straigh to humans without genetic change
• Influenza strain passes to immediate host alongside human strain which are reasserted and this strain then passed to humans
• Influenza strain passed directly to humans without genetic change

Question 10

Influenza vaccination

Answer 10

• Aged 65 and older
• Young children
• Pregnant women
• Chronic health conditions (i.e. asthma, COPD, HF, DM)
• Healthcare workers and carers

Question 11

Diagnosis of influenza

Answer 11

• Viral nasal or throat swabs to virology for PCR

Question 12

Management of influenza

Answer 12

• Healthy patients require no treatment
• Those at risk of complications can either use oseltamivir PO or zanamivir INH - also given as PEP to those with chronic conditions or immunocompromised

Question 13

Complications of influenza

Answer 13

• Otitis media, sinusitis and bronchitis
• Viral pneumonia
• Secondary bacterial pneumonia
• Worsening of chronic health conditions
• Febrile convulsions (young children)
• Encephalitis