Listeria outbreak causes widespread chicken salad recall

As a result of a Listeria outbreak, a popular delicatessen item has been removed from Western Australian supermarket shelves.

On February 12, the Zimbulis Caribbean mango chicken pasta salad was recalled from Woolworths, IGAs and corner shops in the state following the discovery of the contamination.

Listeria monocytogenes is a germ that can grow in cold temperatures, such as a fridge or cold store. With this in mind, ready-to-eat deli meats such this chicken pasta salad are common breeding grounds for the germ.

In stark comparison to Salmonella or E.coli, food contamination with Listeria doesn’t show any sliminess or odour – meaning it is up to the retailer to ensure hygiene is up to standard and food isn’t left to decay.

Listeria has gained media attention in recent years after a spate of illnesses involving pregnant women and their unborn babies. The germ also can have a major impact on the elderly or people with low immune systems.

Data logging and cleaning imperative

This Western Australian case is a prime example of what Purdue University in Indiana recently investigated.

Researchers at the university found that Listeria bacteria in delicatessens is higher than what would be acceptable in the manufacturing process. This means that most commonly the source of the Listeria bacteria is the retailer – not the manufacturer.

In the first test, 6.8 per cent of samples taken across 15 delis tested positive for the germ. The university then conducted a second round of testing over six months and found 9.5 per cent of samples taken in 30 delis were also rife with the bacteria.

It is important to note that in 12 of the locations, the same subtype of the bacteria kept occurring over several months. The germ has an incubation period of between three and 70 days which means if supermarkets aren’t cleaning properly or keeping temperatures correct – the bacteria aren’t killed.

Researcher Haley Oliver explained the consequences of these findings.

“These data suggest that failure to thoroughly execute cleaning and sanitation protocols is allowing L. monocytogenes to persist in some stores,” she said.

“We can’t in good conscience tell people with weak immune systems that it is safe to eat at the deli.”

Ms Oliver noted that it is important for food retailers to put proper processes in place given the commitment to hygiene shown from manufacturers.

“The challenge of developing systematic cleaning procedures for a wide variety of delis – which are less restricted environments than processing plants – can make Listeria harder to control,” she concluded.