To make somebody enthusiastic about one's own passion, or to communicate a feeling to others, or a feeling communicating itself to others.
To bring (the body or part of it) into contact with a substance that causes illness (a pathogen), so that the pathogen begins to act on the body; (of a pathogen) to come into contact with (a body or body part) and begin to act on it.
To contaminate (an object or substance) with a pathogen.