Systemic means “affecting the entire body,” rather than a single organ or body part. For example, systemic disorders such as High blood pressure or systemic diseases such as Influenza affect the entire body.
An infection that is in the blood stream is referred to as a systemic infection. In contrast, an infection pertaining to one body part or organ is referred to as a localized infection.
by Arthur A. Poghosian, M.D.