2009 Influenza A (H1N1) virus

History & exam

Key factors

  • fever and chills
  • cough
  • sore throat

Other diagnostic factors

  • runny nose
  • age (increased risk of complications)
  • comorbidities (increased risk of complications)
  • immunosuppressive medication
  • pregnancy (increased risk of complications)
  • smoking (increased risk of complications)
  • residence in a nursing home (increased risk of complications)
  • presence of ill contacts, or residence in or travel to pandemic areas
  • constitutional symptoms (fatigue, headache)
  • myalgia and arthralgia
  • tachypnoea
  • nausea, abdominal pain, diarrhoea
  • extreme irritability (young children and infants)
  • altered mental status/lethargy (young children and infants)
  • seizure
  • severe shortness of breath
  • hypotension
  • wheezing
  • crackles

History & exam details

Diagnostic tests

Tests to consider

  • rapid influenza antigen test
  • real-time reverse transcriptase (rRT)-PCR
  • viral culture
  • immunofluorescent antibody staining
  • FBC
  • CXR

Diagnostic tests details

Treatment details

Presumptive

high-risk patients who have had close contact with an infectious person

  • antiviral prophylaxis

Acute

pregnant

  • supportive care + antipyretics + antiviral therapy

non-pregnant adults: previously healthy

  • supportive care + antipyretics
  • with severe symptoms
    • antiviral therapy

non-pregnant adults: high risk of influenza complications

  • supportive care + antipyretics + antiviral therapy

children <5 years: previously healthy

  • supportive care + antipyretics
  • symptom onset within past 48 hours or severe disease
    • antiviral therapy

children ≥5 years: previously healthy

  • supportive care + antipyretics
  • with severe symptoms
    • antiviral therapy

children: high risk of influenza complications

  • supportive care + antipyretics + antiviral therapy

Treatment details

Last updated: Dec 30, 2011
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