Flu viruses are categorized into four types: A, B, C and D. Types A and B are the most harmful to humans and cause seasonal flu epidemics; in the Northern Hemisphere, flu season typically occurs ...

Alongside being rarer, it tends to cause more severe illness in children and often circulates later in the flu season, peaking in spring. Stock image of a man with the flu. Stock image of a man ...

bird flu is a disease caused by the influenza A virus. At the same time, recent CDC data shows that seasonal influenza A is rising across the U.S. — specifically the H1N1 (swine flu) and H3N2 ...