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Symptoms and Signs of Bird Flu or Avian Flu (H5N1, H7N9)

Doctor's Notes on Bird Flu or Avian Flu (H5N1, H7N9)

Bird flu (avian influenza) is an illness that affects wild and domesticated birds and typically causes either little or no symptoms unless the bird population is susceptible, in which case it may cause death in many birds within about 48 hours. Human infection with bird flu is rare, but when it occurs, it is often fatal. The virus spreads from bird to bird from the saliva, nasal secretions, and droppings of infected birds. Humans get bird flu through close contact with sick or dead poultry, or from exposure in poultry markets in some countries (mainly Asia, Europe, the Near East, and Africa) known to harbor the virus.

Symptoms of bird flu in humans are typical flu-like symptoms, including fever (above 100.4 F), cough, shortness of breath, wheezing, sore throat, and muscle aches. Other symptoms of bird flu in humans may include nausea, vomiting, diarrhea, encephalitis (brain infection), or eye infections. Bird flu infection can progress to pneumonia and respiratory failure.

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/11/2019


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.