Almonds linked to Salmonella Typhimurium outbreak
In late September, notification numbers for Salmonella Typhimurium phage type 3 (STm PT 3) — a rare type of Salmonella in Australia — increased nationally.
Interviews of cases revealed that a high proportion had eaten raw almonds prior to becoming ill. In October, OzFoodNet, an Australia-wide network of epidemiologists, began a multi-jurisdictional outbreak investigation, working with food safety officers in each jurisdiction. It found more than 30 cases of salmonellosis were linked to this outbreak, with cases reported in all six states.
As the phage typing method for subtyping STm is not conducted in Western Australia, isolates of the outbreak strain were sent to WA from interstate for pulsed-field gel electrophoresis (PFGE) typing, which is the method used here for the subtyping of STm. The STm PT 3 isolates were found to be equivalent to PFGE type 0434, which has only recently been identified in WA. Five cases of PFGE type 0434 were identified in WA in September and October.
A national recall of Woolworths raw almond kernels was conducted on 4 October as a result of STm PT 3 being found in raw almonds. Close monitoring of STm isolates is continuing around the country.
All 5 WA cases reported regular almond consumption, with 2 confirming consumption of Woolworths raw almonds, specifically, prior to becoming ill. One case was aware of the product recall prior to interview because they had received an alert from Woolworths via their ‘Everyday Rewards’ loyalty card membership, which records all purchases made by the cardholder. Two cases had leftover almonds, which were submitted for testing. One almond sample was positive for STm PFGE type 0434.