The Symptoms of Seasonal Flu Versus Avian Influenza

Agricultural Disaster Preparedness and Recovery October 05, 2012 Print Friendly and PDF

Seasonal Flu vs. HPAI H5N1

While seasonal flu and bird flu are both respiratory illness caused by viruses in the Orthomyxovirus family, they exhibit many differences. Below is a chart that compares seasonal flu (H1N1) to the highly pathogenic avian influenza (HPAI) H5N1 virus.


  Seasonal flu Highly Pathogenic Avian Influenza (HPAI)
  • Fever
  • Headache
  • Fatigue
  • Dry cough
  • Sore throat
  • Runny nose
  • Muscle aches
  • Diarrhea

Due to the infrequent cases of HPAI H5N1, definitive symptoms are difficult to determine. However, bird flu will probably begin like seasonal flu, with the severity of symptoms drastically increasing over the first 12-24 hours.

  • Typical flu symptoms
  • Eye infection (Conjunctivitis)
  • Pneumonia
  • Acute respiratory distress
Time Frame
  • Flu season generally occurs between November and March.
  • If bird flu were to become pandemic, infection could occur at any time of the year.
  • Primarily transmitted by direct contact with an infected person’s nasal or oral secretions (sneezing, coughing).
  • Transmitted easily from person-to-person.
  • Primarily transmitted when a person’s mucus membranes (eyes, nose, mouth) come in direct contact with an infected birds saliva, nasal secretions, or feces.
  • NOT easily transmitted from bird-to-human or person-to-person.
Location of Infection
  • Upper respiratory infection.
  • Lower respiratory infection.
High Risk Population
  • Those aged 65 and older.
  • Children younger than 2.
  • Those with chronic medical conditions or compromised immune systems.
  • Previously healthy young adults and children who have contact with poultry.
  • Most infections occur in people younger than 40.
  • 5-20% of the world's population gets the flu each year, with three to five million serious cases.
  • As of January 2011, there have been 516 confirmed human cases of HPAI H5N1.
  • Rest
  • Fluids
  • Over-the-counter medications
  • Antiviral drugs may be prescribed for serious cases.
  • Antiviral drugs such as Oseltamivir (TAMIFLU®) and Zanamivir (RELENZA®) would likely be effective in treating HPAI H5N1, but additional studies still need to be completed to demonstrate their effectiveness.
Mortality Rate
  • Less than 0.1% of those infected die.
  • Approximately 60% of those infected die.
  • Vaccines are inexpensive and readily available.
  • In 2007, the FDA approved an avian influenza vaccine against one strain of HPAI H5N1 for humans; however, it is not commercially available to the public. The vaccine remains in the national stockpile and will be released in the event of a pandemic.

Test your Flu IQ.




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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.