New South Wales Health has confirmed that another nursing home patient has fallen ill with salmonella poisoning in the Illawarra region.
Two people have died since the outbreak first surfaced on January 21.
Twenty-eight people became sick at 10 aged care centres in the Illawarra, southern Sydney and the ACT.
Despite an ongoing investigation by NSW Health the cause of the outbreak is still unknown.
Spokesman Curtis Gregory said the elderly population were more vulnerable to an outbreak than the normal population.
He said it was very difficult to isolate the source in this instance.
“With normal food outbreaks what you get is a single incident – so it might be a single meal, a single event or function. With this one it’s across 10 different facilities,” he said.
“We’re looking at a menu cycle of four weeks, we’re chasing data that’s several days old and their memory’s not quite as good as it used to be.
“So all these factors add up and it makes it quite difficult in this situation to find a source and identify it.”
He said the NSW Food Authority is looking into whether the problem occurred during preparation or with the food itself.
“It tends to go through one central kitchen for all the different facilities and that’s where we think the source has been, whether it’s in the kitchen or through a supplier and the Food Authority are actually carrying out that side of the investigation,” he said.
The Illawarra Retirement Trust (IRT) said 25 of the cases, including the latest, occurred at one of its facilities.
While early investigations focused on salad as the possible source of the outbreak, health authorities week turned their attention to bakeries supplying cakes and pies.
A Wollongong wholesale baker was temporarily closed by the NSW Food Authority then later cleared and allowed to re-open, but it no longer supplies food to the IRT.
Meat and vegetables were not ruled out as a potential source of the salmonella contamination.