Clinical Definition

A pathogen is any microorganism or agent that invades another organism and causes disease or illness in its host. Pathogens are transmitted to the host via various pathways and have varying degrees of virulence.

In Our Own Words

A pathogen is any organism that can enter the body and make you sick. Pathogens can cross the threshold in different ways, such as through your digestive tract, blood, lungs, mucus membranes and cuts to the skin. Safeguards against pathogens include thorough hand washing and proper hygiene, food safety, healthy living and vaccination. After you are infected, however, a health care practitioner may recommend further use of antibiotics, antiviral medications and antifungal agents.