The term that refers to disease-causing organisms that invade the body is pathogens.

Here are some other terms that are sometimes used interchangeably with pathogens:

* Infectious agents

* Germs

* Microbes (although not all microbes are pathogenic)

Pathogens can be bacteria, viruses, fungi, parasites, or prions. They cause disease by damaging cells and tissues, interfering with normal bodily functions, or triggering an immune response that harms the body.