Case participants or their guardians were interviewed by telephone with a short standardised questionnaire obtaining information
about demographics, travel, health, and specific details about chicken
meat and egg consumption in the seven days before the onset of the
illness. The questionnaire also included specific questions about the
consumption of foods that may contain raw egg and general
environmental exposures (including animal contact, gardening,
drinking from a private water supply, and recreational water contact)
in the seven days prior to illness, based on previous OzFoodNet
questionnaires. This was chosen as the questions were part of an
established tool commonly used nationwide for foodborne disease
outbreaks. The questionnaire was also piloted once developed.