noun, Psychology. 1. Also called operant conditioning, instrumental conditioning. a process of changing behavior by rewarding or punishing a subject each time an action is performed until the subject associates the action with pleasure or distress.
Pertussis is caused by the bacterium Bordetella pertussis. It is an airborne disease which spreads easily through the coughs and sneezes of an infected person. People are infectious to others from the start of symptoms until about three weeks into the coughing fits.
Description and significance. Bordetella pertussis is a small, Gram-negative, coccoid bacterium about the size of 0.8 Âµm by 0.4 Âµm. It is an encapsulated immotile aerobe that does not make spores. Bordetella pertussis produces a number of virulence factors, including pertussis toxin, adenylate cyclase toxin, filamentous hemagglutinin, and hemolysin. It cannot survive in the environment; it must reside in a host either in small groups or singly.