What term refers to an agent that causes disease?

The term that refers to an agent that causes disease is "pathogenic." This word specifically describes microorganisms, such as bacteria, viruses, fungi, and parasites, that have the potential to cause illness in a host. Understanding pathogenic agents is crucial in fields like microbiology and infectious disease control, as they play a significant role in public health and the prevention of disease transmission.

In contrast, "infectious" generally describes a disease that can be transmitted from one individual to another, which does not define the nature of the agent itself but rather the property of the disease. "Infection" refers to the process by which pathogens invade and multiply in the body, leading to a disease state. "Inflammation" describes the body's response to injury or infection, characterized by redness, heat, swelling, and pain, which does not pertain to the agent that causes the disease but rather to the body's reaction to it. Thus, "pathogenic" is accurately the term that identifies the causative agents of diseases.