Viral Respiratory Infections

Question 1

Name the some viruses which can cause a respiratory infection

Answer 1

• Double stranded DNA: Adenovirus,
• Positive single strand RNA: Coronavirus, MERS-CoV, Rhinovirus
• Negative single stranded RNA: Influenza, parainfluenza, RSV

Question 2

What are the routes of transmission of RTIs?

Answer 2

• Aerosols,
• Droplet spread,
• Fomites

Question 3

Adenovirus can result in what?

Answer 3

• Rhinorrhea,
• Pharyngitis (think bacterial/EBV if exudative tonsillar hypertrophy, think fungal if curd like plaques on tounge)
• Pharyngoconjunctival fever,
• Otitis media in children,
• Tracheitis,
• Pneumonia
• Non respiratory infections

Question 4

What can the common cold cause in children and elderly patients?

Answer 4

Children: URTI, croup, otitis media, pneumonia with wheeze and diarrhoea/necrotising enterocolitis.
Elderly: Flu like illness, pneumonia, infective exacerbation of COPD

Question 5

Describe features of MERs-CoV

Answer 5

• Endemic in middle east. Similar clinical syndrome to common cold coronavirus but more likely to cause pneumonia.

Question 6

What can rhinovirus cause?

Answer 6

• Upper resp tract infection,
• Bronchiolitis in children under age 5,
• Pneumonia in children under 5/elderly.
• IE of COPD

Question 7

What are the different influenza viruses?

Answer 7

Influenza A - Mutates rapidly and can cause pandemics.
- Influenza B - mutates rapidly, causes epidemics but vaccine available.
- Influenza C - minor outbreaks occur and only causes a mild disease

Question 8

What are the symptoms of influenza

Answer 8

• Systemic symptoms such as fever, myalgia, GI disturbances followed by URTI symptoms.
• Complications: Meningoencephalitis, pneumonia, secondary bacterial infections and Guillain-Barre syndrome. The patients at risk of complications are: pregnant women, extreme ages, patients with chronic disease, immunosupression and morbid obesity.

Question 9

Describe features of avian influenza

Answer 9

• Cause pneumonia and lower respiratory infections as it prefers cells in lower resp tract.
• Different strains eg, H5N1 however do not infect humans very well and only tends to affect people who work with poultry. However risk of virus mutating and causing a pandemic

Question 10

What are the current influenza strain circulating?

Answer 10

• H1N1,
• H3N2

Question 11

What can arise due to parainfluenza infections?

Answer 11

• Otitis media
• Croup in HPIV 1 and 2,
• Bronchiolitis (HPIV 3)

Question 12

What are the symptoms of croup?

Answer 12

It is a childhood disease which can cause:
- Croupy cough,
- Inspiratory stridor,
- Hoarse voice,
- Difficult during inspiration with in-drawing of chet wall in subcostal, intercostal and supraclavicular spaces,
- Rhonchi (bubbling/gargling sounds heard with breathing)
Often requires hospitalisation

Question 13

Describe features of respiratory syncytial virus and metapneumovirus

Answer 13

• 1st infection always symptomatic, and can result in: Bronchiolitis mainly in children under 3, this can cause atelectasis dur to proliferation and necrosis of bronchial epithelium. Tracheobronchitis, croup, rhinitis, or otitis media with fever

Question 14

How are viral respiratory infections diagnosed?

Answer 14

Via PCR of swabs. A basic respiratory PCR investigates for: SARS-CoV-2, Influenza A and B, RSV and adenovirus or mycoplasma pneumoniae.

Question 15

What is the treatment for viral respiratory infections?

Answer 15

• Supportive treatment for most.
• Antivirals used for some infections in immunocompromised patients eg, Neuroaminidase inhibitor (NA inhibitors) in influenza which are sialic acid analougues and prevent virus from detaching from host cell. Eg,
  1st line - Oseltamivir 75 mg BD for 5 days (tablets) for H3N2.
  2nd line - Zanamivir inhalations 10mg BD for 5 days for H1N1.