Salmonella was behind almost a third of fresh produce-associated outbreaks in Australia analyzed over a 17-year period.
Scientists examined confirmed and suspected outbreaks caused by fresh produce recorded in OzFoodNet from 2001 to 2017. OzFoodNet is Australia’s national network for foodborne disease surveillance and response.
According to the study published in Communicable Diseases Intelligence, 92 outbreaks were reported, with 3,422 illnesses, 446 hospitalizations, and four deaths. The deaths occurred in outbreaks that implicated semi-dried tomatoes or melons.
Of these outbreaks, 70 were caused by a known pathogen, with 30 due to Salmonella and 29 to Norovirus. 71 outbreaks were associated with foods containing multiple ingredients, some of which were not fresh produce.
Sprouts and melons
The largest outbreaks associated with a single produce item included mung bean sprouts contaminated with Salmonella Saintpaul with 419 illnesses and 76 hospitalizations in 2016 and imported semi-dried tomatoes contaminated with Hepatitis A that led to 372 illnesses and 169 hospitalizations.
Among the 30 Salmonella outbreaks, Typhimurium caused 12, and Saint Paul had four. There was only one outbreak of Listeria monocytogenes, which led to eight hospitalizations and two fatalities.
Norovirus infections do not need to be reported to public health surveillance, making outbreaks difficult to detect. The study also linked the Hepatitis A virus to three frozen berry outbreaks.
Nine outbreaks were associated with fresh produce in 2009 and 2014, and only two in 2004.
Restaurants and commercial catering were standard settings for outbreaks. These were frequently due to multiple-ingredient mixed dishes and salads containing fresh produce. Norovirus infections were mainly associated with settings and meals where food handlers were likely to be an important source of contamination.
Sprouts were the most common single-ingredient primary fresh produce item associated with outbreaks, followed by melons.
Incidents occurred in all states and territories and all seasons, with an increased frequency in the warmer months of September to May. There were 11 multi-state outbreaks.
“We conclude that the consumption of fresh produce in Australia produces a significant but relatively small number of outbreaks of foodborne illness that has remained largely unchanged in size and aetiological agent across the 16 years analyzed in this report. Consistent with global patterns, sprouts and melons are significant vehicles of bacterial pathogens and can result in severe illness,” said scientists.
New rules are getting closer
New food safety standards for growers of berries, leafy vegetables, and melons will take effect on Feb. 12, 2025.
National standards were developed in 2022 by Food Standards Australia and New Zealand (FSANZ). An assessment identified common risk factors for microbial contamination, including incursion by wildlife and domestic animals; location of growing areas near sources of contamination; extreme weather; use of untreated manure; contaminated water; inadequate sanitization processes; and poor hygiene practices during harvest and postharvest handling.
Control measures to minimize risks include good agricultural and hygienic practices at harvest and postharvest, responding to changes in the growing environment, and controlling inputs.
Emily Scott, Agriculture Victoria horticulture standards engagement officer, said the rules will help lift food safety standards across the industry.
“We are working closely with industry bodies and growers to support businesses implementing the new standards with a timely awareness and engagement campaign. The standards apply to businesses of any size that grow or complete primary or early-stage processing, such as washing, trimming, sorting, sanitizing, or storing berries, leafy vegetables, or melons. It is worth noting that many businesses are already meeting the requirements in the standards through their participation in industry food safety schemes,” she said.
Agriculture Victoria is holding a webinar on Dec. 10 for berry, leafy vegetables, and melon producers to learn more about the Primary Production and Processing Standards. The webinar will cover microbial food safety risks, what is required to comply with the standards for each industry, how Global Food Safety Initiative schemes will be recognized, costs, and where to access information and resources.
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