A batch of bad eggs has been blamed for a salmonella outbreak linked to the death of one elderly woman and sickness in hundreds of others.
At least 220 people have reported being sick and a 77-year-old woman's death has been linked to the food poisoning outbreak.
Included among those 220 people were 11 departmental staff members from the office of Premier and Cabinet.
A salmonella outbreak has been linked to a Brisbane catering company.
Piccalilli Catering, a Brisbane company that provided the catering for 40 different Melbourne Cup functions last week, has released a statement blaming eggs used in fresh mayonnaise for the oubreak.
"We are deeply upset and distressed by this outcome," co-owner Helen Grace said.
"We always pride ourselves on sourcing the freshest Australian ingredients for our kitchens.
"We feel very disappointed and let down that the normally reliable fresh food supply chain has failed us – and our clients – on this occasion.
"Having sourced those eggs from a normally reputable fresh food market, we had no reason to believe they were not up to the very high standards we demand of our suppliers."
Ms Grace said Piccalilli would no longer source produce from this supplier.
"We will leave it to our insurers and lawyers to determine what other action should be taken," she said.
"It is of some comfort to know that there has not been a breakdown in our own quality systems. Indeed, we have never experienced an incident such as this in 25 years as professional caterers."
Ms Grace said the company would undertake a "thorough" investigation of its supply chain arrangements and would continue to co-operate with Queensland Health and Brisbane City Council.
Metro North Public Health Unit Director Susan Vlack urged anyone who was worried to see their doctor.
Symptoms, which include fever, headache, nausea, diarrhoea, abdominal pain and vomiting, usually present within six to 72 hours after exposure.
Dr Vlack said while the elderly woman who died did have a salmonella infection, it was not the cause of her death.
Investigations were under way to determine whether it contributed, she said.
The Metro North Public Health Unit received its first notification of illness on November 8.
"We had one report from one venue and the next day, we had three or four, I think," Dr Vlack said.
"So that was when we decided we need to be very careful and cover all our bases with this investigation.
"Salmonella outbreaks in a small scale are pretty common, particularly in the warmer months of the year, but this is unusual to have so many cases all at once."
At risk Melbourne Cup function attendees, who were mainly from events dotted around the Brisbane CBD, were contacted in the last 24 hours.
Of the almost 700 people who were potentially at risk, 220 were considered to have been affected. Seven were admitted to hospital and two are considered "fairly ill".
Dr Vlack said Piccalilli, which had been cooperating, has voluntarily stopped its catering arm.
"It is an investigation, there may be legal proceedings, we have to be very careful and make sure we have all our information tied down," she said.
"I think the general message is, if you have been to a Melbourne Cup lunch and you do get ill… particularly with fever and diarrhoea...then you should see your doctor."
Salmonella can spread to humans via contaminated food, especially meat, poultry, eggs and their by-products.
Most people recover within a week with no more than rest and fluids needed, but young children, the elderly and those already sick are considered vulnerable.