The flu (influenza) is a serious virus that causes millions of illnesses each year. Symptoms include sneezing, muscle aches, and a fever. Most cases of the flu are mild enough to treat yourself at ...

The ongoing spread of highly pathogenic bird flu worldwide is reaching an unprecedented scale, a United Nations agency warned Monday.

Bird flu is caused by several types of influenza A viruses. It primarily affects wild and domestic birds, but can also infect mammals. Symptoms in humans include fever, cough, fatigue, sometimes ...