Respiratory viral infections

What are the typical symptoms of influenza?

• Abrupt onset

• Headache, fever, cough, sore throat

• Muscle and joint aches

• Sometimes gastrointestinal symptoms

Which groups are at higher risk of complications from influenza?

• Older adults (>65 yrs)

• People with underlying health problems (e.g., asthma)

• Young people with no prior immunity

What are the main complications of influenza?

• Bacterial pneumonia

• Bronchitis

What are antigenic drift and antigenic shift in influenza, and why do they matter? 

• Antigenic Drift: minor, gradual mutations in H & N antigens → seasonal flu changes

• Antigenic Shift: major abrupt change when different strains combine → new subtype → previous immunity may not protect → risk of epidemic/pandemic

Who is at higher risk of serious illness from influenza?

• Children <6 months

• Older adults

• Underlying health conditions:

• Pregnant women:

When are antiviral drugs indicated for adults with influenza?

• Within 48 hours of symptom onset

• Adults >65 yrs, <6 months, pregnant

• AND chronic condition(s) or previously healthy but at serious risk of complications

• Drugs: Oseltamivir (oral), Zanamivir (inhaled)

What is post-exposure prophylaxis for influenza in at-risk adults?

• For at-risk patients potentially exposed to flu from a close contact

• Oseltamivir: start within 48 hrs of exposure

• Zanamivir: start within 36 hrs of exposure

How do oseltamivir and zanamivir work against influenza?

• Oseltamivir (Tamiflu): synthetic prodrug → blocks viral neuraminidase, stopping release of new viral particles

• Zanamivir (Relenza): inhibits viral neuraminidase, may alter virus particle aggregation and release

How common is the common cold , and what causes it? 

• Causes: Rhinoviruses and coronaviruses

• Type: Usually upper respiratory tract infection

What are the typical symptoms of the common cold?

• Blocked/runny nose, sneezing, sore throat, cough, laryngitis, tirdness

• Self-limiting ~1 week (longer in children)

• Cough can last up to 3 weeks

What are the complications of the common cold?

• General: Lower respiratory tract infections, sinusitis,

• Young children: Bronchiolitis, pneumonia

What are the main supportive treatments for mild respiratory viral infections?

• Rest, hydration, healthy diet

• Steam inhalation

• Vapour rubs

• Salt water gargles, menthol sweets

Which topical or nasal treatments are recommended for the common cold

• Saline nasal drops

• Topical decongestants (>6 yrs): Short-term use; risk of rebound congestion

• Steroid nasal spray:

hat oral medications can be used for adults and older children with the common cold?

• Oral decongestant/antihistamine/analgesic combo:

• ibuprofen or paracetamol as anti-pyretic and pain-relief
  

Avoid in under 6 years 

• Antitussives

• Expectorants

• Topical and oral decongestants

• Antihistamines

When should a patient with a common cold be referred?

• Cold lasting >3 days

• Symptoms worsen over 5 days

• No improvement by 10 days (except mild cough/mucus)

• Concern for: lethargy, decreased responsiveness, or difficulty breathing

Which patients should be “safety-netted” sooner for complications from a common cold?

• Young children/babies, especially with:

  • Dehydration

  • Laboured breathing

  • Prolonged fever