Parasites can be divided into three categories; those which live in your body, those that are passed through the food chain and those that are found on the surface of the body. I will cover both of these classes separately, and then show you the advantages and disadvantages of each type of parasite.
When I speak of the parasitic microbe or microorganism, I mean an organism that is either native to or can survive in your body. The organisms in the first category include such pathogens as bacteria, viruses and fungi. In the second category are parasitic bacteria, or protozoa, which also live in your body and are usually carried by animals. These organisms usually infect the nervous system. Third, and a separate category, are protozoa that live outside the body. The parasite organisms in this class of organisms are all in your digestive system, from where they infect the intestine and the bloodstream. This is why the doctor may refer to these as "intestinal" pathogens. This category of organisms include such microorganisms as parasites and fungal pathogens, such as the intestinal fungi (bacterial, fungal and bacterial). Finally, the doctor will also include parasites in their diagnostic class.
What do you call an organism that has the capacity to infect a wide range of tissues, such as a virus or a bacteria? Parasite.