Host–pathogen interaction

Host–pathogen interaction is when a small living thing, called a pathogen, tries to live and grow on or inside a larger living thing called a host. A host could be an animal, a plant, or even a person. Pathogens could be things like viruses and bacteria. When a pathogen first tries to get into the host, the host's body will try to keep the pathogen out. If the pathogen is successful in getting into the host, it will start to grow inside the host and cause an illness. The host and the pathogen can both fight each other to try and win - the pathogen trying to survive and grow, and the host trying to stay healthy and get rid of the pathogen.