Food-borne disease outbreak investigation

Food Outbreaks
Food-borne disease outbreak investigations requires a coordinated approach between various government agencies

The identification, investigation and control of a food-borne disease outbreak requires the coordination and sharing of information between various government agencies including:

  • Local Governments
  • Environmental Health Directorate, WA Department of Health
  • Population Health Units, WA Department of Health
  • OzFoodNet (WA); and
  • PathWest

All government agencies work together during a food-borne disease outbreak investigation, collecting and sharing information to identify, investigate, control and prevent the continuance and where possible the recurrence of an outbreak.

From time to time, outbreaks may involve multiple local governments. When this occurs, the Environmental Health Directorate will coordinate the investigations through the relevant local governments.

Irrespective of the size of the outbreak, a complete outbreak investigation involves three components:

  • laboratory investigations
  • epidemiological investigations and
  • environmental health investigations.
Roles and responsibilities

Local government

In response to an outbreak local governments may:

  • take appropriate action in response to information indicating that an outbreak is occurring, or has occurred in a food business.
  • undertake an onsite food safety investigation of the food business or food believed to be linked to the food-borne disease incident or outbreak.

Environmental Health Directorate, Department of Health

In response to an outbreak the Environmental Health Directorate:

  • support local government in coordinating the environmental health investigation
  • take appropriate action in response to information indicating that an outbreak is occurring either in:
    • public hospitals
    • dairy (primary production, processing and transportation)
    • primary production of seafood (manufacturing of seafood which includes bi-valve molluscs)
    • a food business not within a district (for example Rottnest Island, King’s Park).

Population Health Unit, Health Service Providers

In response to an outbreak the Population Health Unit may:

  • conduct epidemiological investigations into single incident cases of enteric disease caused by:
    • cholera
    • hepatitis A and E
    • Salmonella Paratyphi
    • Shigella disenteriae
    • Salmonella Typhi that occur in rural areas.


In response to an outbreak OzFoodNet may:

  • determine the incidence and patterns of food-borne disease in the community
  • identify possible sources for the food-borne disease through interviewing ill cases and studying epidemiological data.
Guidelines for enforcement agencies

The Guidelines for the Environmental Health Investigation of a Food-borne Disease Outbreak (PDF 1.42MB) (the Guidelines) has been developed to assist enforcement agency authorised officers in the investigation and control of a food-borne disease outbreak caused by biological agents.

The summary of the onsite investigation process for a food-borne disease outbreak (Word 122KB) can be used as a quick reference guide when investigating food-borne disease outbreaks in the field.

Specifically, the Guidelines provide authorised officers with step-by-step guidance: from the time the local government is notified of a known or suspected food-borne disease case to the onsite investigation and the implementation of preventative measures.

The Guidelines include:

  • clarification on each agency’s roles and responsibilities (Section 2)
  • types of food-borne disease outbreaks (Section 3)
  • the local government notification process (Section 3).
  • an outline of a comprehensive procedure for environmental health investigations (Section 4)
  • examples of appropriate control measures for food-borne disease outbreaks (Section 5)
  • useful directions on laboratory requirements for environmental health sampling and analysis (Section 6).
  • information on communication with external stakeholders (Section 7)
  • contact details of relevant stakeholders (Section 8).

The appendices contain supporting documentation such as technical advice, instructions and templates that may be useful during the investigation.

The Guidelines can also be applied to the investigation of a single case food-borne disease incident.

Confirmed case definition

A confirmed case is an ill person who:

  • has had a food-borne disease pathogen confirmed in a faecal sample specimen by a laboratory and
  • has been epidemiologically associated with a particular outbreak by OzFoodNet.
Food sample collection

The collection of food and swab samples plays a key role in investigating food borne illness outbreaks. Samples of any leftover foods, foods prepared in the same manner as implicated foods or any other foods of interest are collected and tested for bacteria including Salmonella, Listeria, Bacillus cereus, E.coli and total plate counts. Swabs can also be used to collect samples of bacteria on surfaces such as preparation benches, utensils and equipment which are also tested for the presence of pathogens.

The Food Sampling Equipment and Collection Guide (PDF 605KB) provides further information about the equipment to use, how to collect a sample and suggested types of samples.

Equipment Order Forms, Food Sample Submission Forms and further information can be obtained from Pathwest Environmental Microbiology Unit (External site)

Enteric infection reports and summary infographics

OzFoodNet is an Australian Government Department of Health and Ageing funded initiative with OzFoodNet epidemiologists positioned in each jurisdiction to improve jurisdictional and national surveillance of enteric infections including food-borne illness.

OzFoodNet produce quarterly and annual enteric disease infection reports.

Notifiable infection disease reports of interest include:

Triennial infographic - snapshot of foodborne outbreak investigation findings

The Environmental Health Directorate in collaboration with OzFoodNet have commenced publishing an infographic summarising food-borne outbreaks investigated in WA. The information will support local government Environmental Health Officers when communicating to businesses about improving food safety practices.


Last reviewed: 30-06-2021
Produced by

Environmental Health Directorate