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a small living organism that is not visible to the naked eye


microorganisms that are part of the normal flora of the body and are beneficial in maintaining certain body processes


microorganisms that cause infection and disease (germs)


simple one-celled organisms that multiply rapidly


one-celled animal like organisms often found in decayed materials and contaminater water


parasitic microorganisms which means they cannot live outside cells of another living organism


these are the smallest microorganisms visible only using an electron microscope

hepatitis B

(serum hepatitis) a diesease cause by the HBV virus and is transmitted by blood, serum and other body secretions

Hepatitis C

a disease caused by the HCV virus and is transmitted by blood and blood containing body fluids


is caused by the human immunodeficiency virus which surpresses the immune system


depending on free oxygen or air


living or active in the absence of free oxygen


the infection or disease originates within the body


the infection or disease originates outside the body


an infection acquired in a health care facility


infections that occur when the defenses are weak

causative agent

The pathogen responsible for causing an infection; also called the infectious agent.


where a causative agent must live


objects contaminated with infectious material that contains pathogens

portal of exit

a way to escape from the reservoir in which it has been growing

mode of transmission

way that the causative agent can be transmitted to another reservoir or host where it can live

portal of entry

a pathway by which the caustive agent enters the host

susceptible host

a person likely to get an infection or disease

chain of infection

Infectious agent, reservoir, portal of exit, means of transmission, portal of entry and susceptible host.


the absence of diesease-producing microorganims


the things that prevent or inhibit growth of pathogenic organisms but are not effective against spores and viruses


group of simple, plantlike animals that live on dead organic matter


the process that destroys or kills pathogenic organisms


the process that destroys all microorganisms both pathogenic and non-pathogenic

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