Key Terms
Microorganism
Single-celled, microscopic organism, invisible to the naked eye.
Pathogen growth factors
Temperature, moisture, pH, oxygen, access to water.
Normal flora
Community of microorganisms that live on a host without causing disease.
Sepsis
The body's extreme, inappropriate immune response to widespread infection; results in multi-organ system failure; can le
Reservoir
Habitat where the pathogen survives, grows, and multiplies.
Carrier
Person who harbors a pathogen but shows no signs or symptoms; can still transmit it. Asymptomatic carrier: carries patho
Portal of exit
The path a pathogen takes to leave the reservoir.
Purulent drainage
Pus; thick white, yellow, or brown fluid from wounds.
Direct transmission
Pathogen transfers directly from infected person to new host; occurs during physical contact (bathing, dressing changes,
Indirect transmission
Pathogen spread through an intermediary; examples include air, food, water, animals, or objects; in hospitals: medicatio
Droplet transmission
Pathogen travels in water droplets released when infected person coughs, sneezes, or talks; droplets are LARGER than 5 m
Airborne transmission
Pathogens carried by dust or evaporated droplet nuclei; SMALLER than or equal to 5 micrometers (5 µm or smaller); remain
Vector transmission
Blood-feeding arthropods (fleas, ticks, mosquitos) transmit pathogen to animals or humans.
Signs
Swelling, redness, heat, pain, loss of function.
Antigen
Anything the immune system recognizes as foreign; triggers antibody formation. Antibody (immunoglobulin): protein create