Viral Respiratory Tract Infections

Question 1

What are the possible respiratory manifestations of adenovirus?

Answer 1

• rhinorrhoea
• pharyngitis
• pharyngoconjunctival fever (sinus infection)
• otitis media (children)
• tracheitis
• pneumonia

Question 2

What are the possible respiratory manifestations of the common cold coronaviruses?

Answer 2

Children: URTI, croup, otitis media, pneumonia with a wheeze, diarrhoea and necrotising enterocolitis in infants

Elderly: flu-like illness, pneumonia (rare), IECOPD

Question 3

What are the possible respiratory manifestations of rhinovirus?

Answer 3

• URTI
• bronchiolitis (children <5 yo) +/- RSV
• pneumonia (children <5 yo + elderly)
• IECOPD

Question 4

Describe the features of influenza A

Answer 4

• mutates rapidly (causes pandemics)
• infects: horses, pigs, birds, marine mammals
• 8 RNA segments

Question 5

Describe the features of influenza B

Answer 5

• 8 RNA segments
• mutates rapidly (causes epidemics)
• infects marine animals

Question 6

Describe features of influenza C

Answer 6

• 7 RNA segments
• minor outbreaks
• mild disease
• infects pigs

Question 7

What are the features of influenza disease?

Answer 7

• systemic features (fever, myalgia, GI disturbance) more prevalent than common colds
• URTI features predominate after 3 days of systemic features

Question 8

What are the risk factors for severe influenza?

Answer 8

• pregnancy
• age <65 or 6 months>
• chronic disease
• immunosuppression
• morbid obesity >40 BMI

Question 9

What are the complications of influenza?

Answer 9

• meningoencephalitis
• pneumonia
• secondary bacterial infection
• Guillain-Barre syndrome

Question 10

What receptors are implicated in avian influenza (bird flu)

Answer 10

• human strain receptor = sialic acid (2,6) galactose (mostly URT)
• avian strain receptor = sialic acid (2,3) galactose (terminal bronchi + alveoli)

Question 11

List the avian strains of influenza and their features

Answer 11

H5N1 = case fatality 53%, affects backyard poultry rather than farms/markets

H7N9 = case fatality 39%, milder disease in poultry (helped by vaccine)

Question 12

What are the respiratory manifestations of parainfluenza?

Answer 12

• otitis media
• croup (HPIV 1 and 2) = cough, inspiratory stridor, hoarse voice, difficulty in inspiration and indrawing of chest, rhonchi (bubbly sounds)
• bronchiolitis (HPIV 3)
• URTI + pharyngitis (HPIV 1 and 2) - children 6 months- 5 years + adults

Question 13

Describe the respiratory manifestations of metapneumovirus + RSV

Answer 13

• range from mild to severe
• bronchiolitis (<3 yo) = proliferation + necrosis of bronchial epithelium resulting in sloughing and air-trapping with hyperinflation = atelectasis with air absorption
• tracheobronchitis
• croup
• rhinitis
• otitis media with fever

Question 14

What is the treatment for viral respiratory infections?

Answer 14

• supportive treatment
• specific antivirals for some infections in immunocompromised
• steroids not helpful

Question 15

Describe the antiviral treatment of influenza

Answer 15

• baloxavir (inhibits cap-snatching = initiation of transcription)
• ribavirin
• favipiravir (rdrp inhibitor = enzyme for RNA synthesis)
• laninamivir (NAI = bind to neuraminidase + prevent virus from detaching from host cell)

Question 16

What is the treatment of avian influenza?

Answer 16

• oseltamivir (if cannot take rifampicin/isoniazid treatment) 75mg twice a day for 5 days
• zanamivir 10mg twice a day inhalation for 5 days = children >5, no response/resistance to first-line, or if H1N1 is dominating strain