2.3 identify the conditions under which an organism is described as a pathogen.
identify the conditions under which an organism is described as a pathogen
A pathogen is any organism that can produce a disease. Pathogens range from viruses so small that thousands will fit side by side in one millimetre to tapeworms that can be several metres long. They are all infectious.
Pathogens may live outside the body, such as the fungus that causes ringworm, inside particular organs, such as parasitic worms in the intestine, in tissues or inside cells. Some information on water pathogens is found below.