The sum total of body mechanisms which interpose barriers to the progress of invasion or multiplication of infectious agents, or to damage by their toxic products. 1. Immunity – That resistance usually associated with possession of antibodies having a specific action on the microorganism concerned with a particular infectious disease or on its toxin. Passive immunity is attained either naturally, by maternal transfer, or artificially, by inoculation of specific protective antibodies (convalescent or immune serum or immune serum (gamma) globulin (human) and is of brief duration (days to months). Active immunity lasting months to years is attained either naturally, by infection, with or without clinical manifestations, or artificially, byinoculation of fractions or products of the infectious agent or of the agent itself, in killed, modified or variant form. 2. Inherent resistance – An ability to resist disease independently of antibodies or of specifically developed tissue response; it commonly rests in anatomic or physiologic characteristics of the host; it may be genetic or acquired, permanent or temporary.
Article Categories:Dictionary of Tropical Medicine