Flu

Question 1

Flu pathophysiology?

Answer 1

• influenza A and B are RNA viruses of the Orthomyxoviridae family
• A is more common, severe, and causes epi/pandemics like H5N1 (aVIan) and H1N1 (swINe)
• B is milder and, unlike A, occurs almost exclusively in humans
• spread through droplets, so masks help prevent transmission.
• 1-3 days incubation

Question 2

how many get flu each year?

Answer 2

• 20 percent of the population are infected each flu season
• most remain Asx carriers, with only 1 in 4 becoming symptomatic
• with mild URTI
• only 1 in 5 symptomatic individuals present to a doctor

Question 3

Sx flu?

Answer 3

• quick onset
• Respiratory symptoms: cough, coryza
• Systemic symptoms: fever, rigors, fatigue, anorexia
• Pain: headache, myalgia
• N, V, conjunctivitis, photophobia

Question 4

Ix flu?

Answer 4

• diagnosis usually clinical

* nasal/throat swabs for viral culture or PCR are useful for confirmation in severe disease

Question 5

Tx flu?

Answer 5

• vaccination reduces infection, symptomatic disease, and complications 50 percent
• whole trivalent vaccine IM
• fragmented nasal vaccine if <13

Indications: toddlers, age >65, diabetes, respiratory disease (COPD, asthma), organ failure (heart, liver, kidney), immunosuppressed

• rest, paracetamol, and hydration

Question 6

Complications of flu?

Answer 6

• pneumonia can result directly from influenza itself or, more commonly, secondary bacterial infection (Strep. pneumo, Staph. aureus, H. influenzae)
• Other local infections: bronchitis, sinusitis, otitis media
• Neurological complications: encephalitis, post-influenza encephalopathy in children, Guillain-Barré syndrome