The investigation of the listeriosis outbreak in the Maritime
Provinces of Canada (Table 1) provided conclusive evidence for
the first time of foodborne transmission of L. monocytogenes.
The outbreak was detected because of the unusually high number
of perinatal listeriosis at a Nova Scotia hospital over a 3-
month period. Caseecontrol studies implicated coleslaw as
the most likely vehicle of infection. Microbiological confirmation
of coleslaw as the source of the infections was obtained by
isolation of the same strain of L. monocytogenes from coleslaw
obtained from a patient’s refrigerator, and from unopened packages
of coleslaw from the manufacturer. Further investigation
indicated that cabbage used to produce the coleslaw was probably
contaminated by sheep manure and the L. monocytogenes
had adequate opportunities to multiply during the storage of the
cabbage over the winter months