What causes the flu?

    Researchedby:
    Morgan Pfiffner, Nick Milazzo

    Fact-checked

    by:

    Mike Murray, James Gaylor
    Last Updated: October 25, 2023

    The flu is caused by influenza viruses, of which there are two types (A and B). Both influenza A and B viruses circulate throughout populations of humans, and are the typical cause of ordinary, seasonal spikes in flu rates. Influenza A viruses are also found in other animals — if they transfer to humans, they can cause flu pandemics, such as bird or swine flu.[1]

    References

    1. ^Christin Peteranderl, Susanne Herold, Carole SchmoldtHuman Influenza Virus InfectionsSemin Respir Crit Care Med.(2016 Aug)