Table 3.

Initial observations that provided evidence to link outbreaks and incident of foodborne listeriosis to specific foods

Initial observations	Nosocomial incidents and outbreaks	Community incidents and outbreaks
Local and or national surveillance and recognition of increase in cases.	H1, H2, H3, H4, H6, H7, H8
Unrelated food testing and, following submission of L. monocytogenes to the reference laboratory for characterisation, the recognition of the same strain amongst isolates from clinical cases of listeriosis.	H5, H9, H10	O1, O2, O4, O6, O7, O8, S5, S9
Food testing of contents of domestic or institutional refrigerator and isolation of the same L. monocytogenes strain as recovered from clinical cases of listeriosis.		O3, S1, S3, S4, S7, S8
Patient suspicion of implicated food or retailer.		O5, S2, S6, S10