Molecular Koch's postulates

Molecular Koch's Postulates are a set of rules that scientists use to figure out if a particular virus or bacteria causes a particular disease. To understand this, it helps to think of each virus or bacteria like a puzzle piece. Scientists assume that, if a certain virus or bacteria puzzle piece fits perfectly with a certain disease puzzle piece, then we can assume that virus or bacteria causes the disease. Molecular Koch's Postulates are the rules that scientists use to figure out if the puzzle pieces fit.