What defines a pathogen?

A pathogen is defined as a biological agent that causes illness or disease. This includes various types of microorganisms such as bacteria, viruses, fungi, and parasites that can invade a host organism and disrupt normal bodily functions, leading to health issues. The ability of pathogens to cause disease may depend on various factors including their virulence, the mode of transmission, and the susceptibility of the host.

Understanding pathogens is crucial in fields such as medicine and public health because they are responsible for a wide range of diseases affecting humans, animals, and plants. Efforts to control and treat infections caused by pathogens hinge on this definition, as it highlights the harmful role these organisms can play in the health of another organism.