Tripod lettuce has been associated with 128 cases of salmonella poisoning according to the latest news release from the Victorian Department of Health today, but production has now fully resumed after a government supervised inspection.

 

The 128 cases includes 10 confirmed and 118 probable cases. The Victorian Department of Health says further laboratory testing is underway as it continues to investigate the cause of the outbreak at Tripod Farms in Bacchus Marsh, Victoria.

 

The voluntary national recall for a number of salad leaf products from Tripod Farmers is still in place and consumers are advised to be aware of the signs and symptoms of gastroenteritis.

 

Cases of salmonella poisoning by state and territory

 

VIC – 9 confirmed and 91 probable cases

SA – 12 probable cases

QLD – 8 probable cases

NSW – 1 confirmed and 5 probable cases

WA – 2 probable cases

ACT – Nil

NT – Nil

TAS – Nil

 

Batches of the same Tripod Farmers lettuce linked to salmonella poisoning cases in Australia may have also been exported overseas.

 

Assistant Secretary for the Australian Federal Government’s Plant Export Operations, Chris Parker, said that a total of three countries including Thailand could have received impacted produce. All these countries have been notified.

 

In the meantime, Tripod Farmers is back to processing and distributing its full range after inspections were carried out by the Victorian Health Department.

 

Tripod says it is still working with the Health Department to help determine the cause of the salmonella.

 

 Major studies connecting fresh produce to salmonella

 

Whist many Australians are aware of the dangers of salmonella and meat or eggs, the recent salad outbreak has taken most by surprise.

 

Despite the connection with meat, poultry and eggs, in recent years salmonella has been increasingly connected with fresh produce internationally.

 

Study No. 1

 

“Salmonellosis Outbreaks in the United States Due to Fresh Produce: Sources and Potential Intervention Measures” published in Volume 6, Issue 6 of Foodborne Pathogens and Disease

 

This 2009 US study states:  “Traditionally, most cases of salmonellosis were thought to originate from meat and poultry products. However, an increasing number of salmonellosis outbreaks are occurring as a result of contaminated produce.”

 

It goes on to further explain that between 2002 – 2003, 31 produce-associated outbreaks of salmonella were reported in the US, whilst only 29 poultry related outbreaks were raised.

 

The study listed contaminated water sources used to irrigate and wash produce crops as a contributing source to a “large number of outbreaks”. It also listed “contact with manure” as a source of contamination.

 

Study No. 2

 

“Factors That Affect Proliferation of Salmonella on Tomatoes Post-Harvest: The Roles of Seasonal Effects, Irrigation Regime, Crop and Pathogen Genotype” published in Volume 8, Issue 12 of the Public Library of Science journal

 

This 2013 study also stated fresh produce was becoming increasingly recognised as vehicle for salmonella.

 

The study explored the link between tomatoes and salmonella and noted that since 2006 at least sixteen salmonella cases had been linked to tomatoes, rockmelon, sprouts, cucumbers, mangoes, pine nuts, pistachios, peanut butter, papayas and peppers in addition to mixed, frozen and processed foods containing plant products.

 

The study found that the irrigation regime did not affect susceptibility of the tomatoes studied to take on salmonella. Tomato maturity and genotype, salmonella genotype, and inter-seasonal differences were the strongest factors affecting proliferation. Red ripe tomatoes were significantly more likely to be infected with salmonella.

 

Study No. 3

 

“Irrigation Waters as a Source of Pathogenic Microorganisms in Produce” a review published in Advances in Agronomy journal 113:73-138 January 2011

 

This third study found “there is increasing evidence that consumption of raw fresh produce is a major factor contributing to human gastrointestinal illness.” It includes salmonella amongst the list of these gastrointestinal illnesses.

 

“There is a rapidly growing body of research documenting and elucidating the pathways of produce contamination by water-borne pathogens,” the authors said.

 

The review examined temporal and spatial variability, and regional differences, in pathogen and indicator organism concentrations in water; direct and circumstantial evidence for contaminated water as a source of food-borne pathogens; fate and transport of pathogens and indicator organisms in irrigation systems, and the role of environmental microbial reservoirs; and current standards for irrigation water quality, and risk assessment.