Avian influenza, sometimes known as bird flu, is a disease caused by an influenza A(H5) virus that mainly affects birds but can also affect mammals, including humans. It primarily spreads from infected birds to humans through close contact with birds or contaminated environments, such as poultry and dairy farms where animals are handled.
Office of Environment, Health, Safety & Security
October 24, 2024
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October 2024
Avian influenza, sometimes known as bird flu, is a disease caused by an influenza A(H5) virus that mainly affects birds but can also affect mammals, including humans. It primarily spreads from infected birds to humans through close contact with birds or contaminated environments, such as poultry and dairy farms where animals are handled. There have also been reports of transmission from other infected animals (such as cows) to humans. Symptoms in humans range from mild to severe, and in some cases, can be fatal. Respiratory symptoms, such as cough, shortness of breath or difficulty breathing, and sore throat are more common, but non-respiratory symptoms such as fatigue and muscle or body aches are also reported. Asymptomatic infection has also been found in humans with exposure to infected animals or their environments. A total of 28 people in the U.S. have tested positive for the influenza A(H5) virus since 2022 to date.