Define the term ‘pathogen’.

The term ‘pathogen’ specifically refers to an organism that typically causes disease in its host. Pathogens can include a variety of microorganisms, such as bacteria, viruses, fungi, and parasites, which have the capability to invade a host's body and disrupt normal physiological functions. This mechanism often leads to the manifestation of disease symptoms and can affect the host's health significantly.

In the context of disease, pathogens are often studied for their roles in infections and illnesses. Understanding how pathogens operate helps in developing treatments, vaccines, and preventive measures to combat infections. Their identification and characteristics are crucial in fields such as microbiology, immunology, and epidemiology, all of which focus on how such organisms influence health and disease dynamics in populations.