Pathogens and parasites are two types of organisms which are very dangerous to the well-being of their hosts. Both pathogens and parasites are similar in that they cause different kinds of diseases by virtue of their stay inside their hosts. However, there are still some noticeable differences between the two. Parasites are organisms that live on or in another organism, deriving benefit from living on or in that organism without contributing to the healthy living or functioning of the organism.
Parasites derive benefit at the expense of the host. Parasites are macro-organisms, which means they can be seen with the naked eye. Examples are ticks, mites, lice, protozoan, helminths, etc. Pathogens, on the other hand, are micro-organisms that are capable of causing diseases. They are often referred to as disease-causing agents, examples are, virus, bacteria fungi, etc. Unlike parasites, pathogens cannot be seen with the naked eye, except through the use of a powerful microscope.