An investigation into a foodborne outbreak in Melbourne, Australia has found the mostly likely source was the relish.

A total of 37 people and one staff member fell ill with a range of symptoms including acute gastroenteritis after attending a catered lunch in the Olympic Room at the Melbourne Cricket Ground (MCG) on April 25.

The Department of Health and Human Services in the state of Victoria investigated the outbreak of gastrointestinal illness at the function on Anzac Day. It did not mention what microorganism caused illnesses. Anzac Day marks the anniversary of the first major military action fought by Australian and New Zealand forces during the First World War

Dr. Brett Sutton, Victoria’s chief health officer, said after three months of investigation, including testing of implicated foods and ingredients, there were no definitive results as to the cause of illness.

“Based on all available evidence, illness was more likely to have been due to consumption of food rather than as a result of chemical or other environmental exposure. The evidence gathered during the investigation, however, revealed that the most likely source of illness was the relish which was served with the entrée of rabbit, chicken and pork terrine,” he said.

Rapid onset

Onset of symptoms for some cases was rapid with several ill attendees assessed by paramedics at the MCG. Seven of those were transported to hospital where they were further assessed and treated in the emergency department before being discharged. None of them needed to be admitted to hospital and no clinical specimens were collected from these patients.

Environmental health officers from Melbourne City Council attended the venue during the investigation, to ensure the premises had conducted a thorough clean-up, to gather information and collect food samples for testing.

Investigations included testing samples of terrine, and ingredients used to make the relish. Interviews were done with 109 guests and staff who attended or worked at the function.

Dr. Sutton said while there was no definitive source identified, evidence gathered during interviews revealed the most likely source of illness was the relish.

“As this was an isolated incident and no issues were found with food processes, there is no ongoing risk to the public and no further action is required. There are often many limitations in foodborne disease outbreak investigations, so it is not unusual for an investigation such as this to result in an inconclusive outcome,” he said.

(To sign up for a free subscription to Food Safety News, click here.)