Under investigation - A case that has been notified but information is not yet available to classify it as confirmed.

Probable - Not applicable.

Confirmed - A clinically compatible illness accompanied by laboratory definitive evidence.

Not a case - A case that has been investigated, and subsequently has been found not to meet the case definition.

Cases can be further classified, if appropriate, as follows:

Pregnancy associated case:

• Cases are classified as pregnancy-associated if illness occurs in a pregnant woman, foetus, or infant aged ≤28 days old; for these cases it is the pregnant woman or mother who is notified as the case but information regarding the foetus or infant should be included on the case report form.
• All other cases are considered not to be associated with pregnancy.

For more information refer to the Listeriosis section of the Communicable Disease Control Manual.