Contributing Factor Definitions

NOTE: NEARS participants started using these revised contributing factor definitions as of January 1, 2022, for outbreaks occurring in 2022 or later. The 2009-2021 definitions are still available for reporting outbreaks that started before 2022.

Explore this page to review technical definitions for the 30 contributing factors for foodborne illness outbreaks, organized around the three types of contributing factors (contamination, proliferation, and survival). Staff from CDC, the Food and Drug Administration (FDA), and state health departments helped revise these contributing factors to show how foodborne illness outbreaks evolve.

Contamination Factors

Factors that introduce or otherwise permit contamination; contamination factors relate to how the etiologic agent got onto or into the food.

Proliferation Factors (bacterial and fungal outbreaks only)

Factors that allow proliferation of the etiologic agents; proliferation factors relate to how the pathogen was able to increase in numbers and/or produce toxic products before the food was ingested.

Survival Factors (bacterial, viral, parasitic, or fungal outbreaks only)

Factors that allow survival or fail to inactivate the contaminant; survival factors refer to processes or steps that should have killed or reduced the pathogen population to below an infectious dose but did not because of one of these factors.