Ch 2 updated copy - THE DYNAMICS OF DISEASE TRANSMISSION Chapter two The Epidemiologic Triangle The Epidemiologic Triangle Agent the cause of the

Ch 2 updated copy - THE DYNAMICS OF DISEASE TRANSMISSION...

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THE DYNAMICS OF DISEASE TRANSMISSION Chapter two
The Epidemiologic Triangle
The Epidemiologic Triangle Agent: the cause of the disease (bacteria, virus, parasite, fungus, mold, chemical, solvent, radiation, heat, nutritional deficiency, rattlesnake poison) Host: an organism that harbors a disease (human or animal) Environment: those favorable surroundings and conditions external to the human or animal that cause or allow disease transmission (biological, social, cultural, physical aspects of the
INFECTIOUS DISEASES
Infectious Diseases All illness due to a specific infectious agent that is spread from an infected person, animal, or inanimate reservoir to a susceptible host, either directly or indirectly, through an intermediate plant or animal host, vector, or the inanimate environment
Pathogen path·o·gen (păth ' ə-jən) n. An agent that causes disease, especially a living microorganism such as a bacterium or fungus.
Bacteria bac·te·ri·um (băk-tîr ' ē- əm) n. , pl. -te·ri·a (-tîr ' ē-ə). Any of the unicellular prokaryotic microorganisms of the class Schizomycetes, which vary in terms of morphology, oxygen and nutritional requirements, and motility, and may be free-living, saprophytic, or pathogenic in plants or animals. [New Latin bactērium, from Greek baktērion, diminutive of baktron ,
Virus vi·rus (vī ' rəs) n. , pl. -rus·es. Any of various simple submicroscopic parasites of plants, animals, and bacteria that often cause disease and that consist essentially of a core of RNA or DNA surrounded by a protein coat. Unable to replicate without a host cell, viruses are typically not considered living organisms. A disease caused by a virus. [Latin vīrus, poison.]
Fungus fun·gus (fŭng ' gəs) n. , pl. fun·gi (fŭn ' jī, fŭng ' gī) or fun·gus·es. Any of numerous eukaryotic organisms of the kingdom Fungi, which lack chlorophyll and vascular tissue and range in form from a single cell to a body mass of branched filamentous hyphae that often produce specialized fruiting bodies. The kingdom includes the yeasts, molds, smuts, and mushrooms. [Latin; perhaps akin to Greek spongos, sphongos , sponge.]
Parasite par·a·site (păr ' ə- sīt') n. Biology. An organism that grows, feeds, and is sheltered on or in a different organism while contributing nothing to the survival of its
Protozoa protozoa (proh-tuh-zoh- uh) Single-celled animals, such as amoebas , that are the most primitive form of animal life. In modern biology , they are classified in the kingdom of Protoctista rather than in the animal kingdom .

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