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Definition of pathogen

  1. Aug 10, 2006 #1

    I am finding different types of definitions for the word "pathogen" on the internet and I am not sure which one is correct (or more correct). At most places, the word is defined as a "An organism that causes disease in another organism" others as "turn of events that leads to a disease disease manifestation followed by harmful effect".

    However, tracing the etymology of the word gives results that are more related to the second definition.

    So is pathogen strickly disease causing microorgansim (or ~small organism) or is there such a thing as chemical pathogen like nervgas or poisonous chemicals?

    Thank you for your time. Have a nice day.
  2. jcsd
  3. Aug 10, 2006 #2
    A pathogen is a biological agent that causes illness. Generally, pathogens are things such as bacteria, protozoa, viruses, fungi, parasites (like tapeworms), and a few proteins.

    The word pathogen is generally not applied to chemical agents that cause illness. Pathogen is usually reserved for biological agents. It doesn't necessary have to be a microorganism as long as it is a biological agent that causes illness.
  4. Aug 10, 2006 #3
    According to 'Microbiology' by Prescott, Harley and Klein: A pathogen is any disease-producing microorganism.
  5. Feb 2, 2012 #4
    A previous reply from me was withdrawn because it had a web reference. There are a series of definitions of pathogen ranging from "any agent that causes disease" through "an agent that causes disease - especially a microorganism" to "a microorganism that causes disease". The French definition of "pathogene" tends to be much more true to what I consider is its original and logical meaning " a specific causative agent of disease". So asbestos, mercury, excessive heat or radiation are all pathogens in the strict sense of the term. There has been a mass action (mis)appropriation of this term over the last 100 plus years - largely due to the preoccupation of the bio-medical world to focus on infective pathogens rather than inanimate pathogens. The outcome is that related words like "pathogensis and pathogenic" have become logically isolated from pathogen. It is rather like assuming an aborigine is a heavily pigmented native Australian though the word simply means "someone who was there from the beginning". When we constrict the set of objects that qualify as a pathogen we simultaneously lose a large element of the logic of language - and in science this is a critical error.
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