pathogen

(noun)

Any organism or substance, especially a microorganism, capable of causing disease, such as bacteria, viruses, protozoa, or fungi. Microorganisms are not considered to be pathogenic until they have reached a population size that is large enough to cause disease.

Related Terms

Examples of pathogen in the following topics:

  • Infectious Diseases Today and in the Developing World

    • Infectious diseases result from the infection, presence and growth of pathogenic biological agents in an individual host organism.
    • Infectious diseases, also known as transmissible diseases or communicable diseases, are clinically evident illnesses resulting from the infection, presence and growth of pathogenic biological agents.
    • Infectious pathogens include some viruses, bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions.
    • These pathogens are the cause of disease epidemics, in the sense that without the pathogen, no infectious epidemic occurs.

  • Colonialism and the Spread of Diseases

    • Trade routes and new world conquests devastated indigenous populations, while being exposed to new pathogens and newly domesticated animals.
    • It is estimated that new virgin soil epidemics (pathogens introduced by Europeans in previously uninfected areas) decimated over "90 percent of the population in Meso-America and the Andes" during the sixteenth century.
    • Trade routes and New World conquests devastated indigenous populations, as they were exposed to new pathogens and newly domesticated animals.
    • The European contribution to global pathogen exposure created a "global homogenization of disease," where no border was left uncrossed in the spread of infectious diseases.