BBC: US stores are recalling onions over contamination fears amid a salmonella outbreak that has caused over 600 people to fall ill. On 1 August, Thomson International recalled their red, yellow and white onions that had been shipped across all 50 US states and Canada since 1 May. Salmonella cases have been reported in 43 states as well as Canada. More here.
Posts from the ‘Microbial Contamination’ Category
Food Safety News: The World Health Organization (WHO) has identified key priorities to improve food safety in the next five years in South East Asia.
The Framework for Action on Food Safety in the WHO South-East Asia Region covers 2020 to 2025 and has guidance for authorities across the food chain and those involved in food safety emergencies, preparedness and response. Several countries are included. More here.
The Center for Produce Safety in the US has prepared key learnings summaries of its Annual Research Symposium, with five sessions held over June and July 2020.
The full set of Key Learnings from the CPS Research Symposium is here. The following text is drawn from the CPS Key Learnings:
During Session 1 held on June 23, 2020, the Symposium explored the use of computer-based modelling to help address two burning issues for the produce industry: understanding potential Listeria growth and persistence in whole produce commodities and the development of sampling strategies to support the validity of assumptions surrounding microbial testing needs and design of acceptable protocols (Key Learnings Session I).
In Session 2, the Symposium expanded the knowledge base on Listeria monocytogenes and its persistence and growth on specific commodities and fresh-cut products and examined novel methods to control Listeria growth on food contact surfaces (Key Learnings Session II).
In Session 3, the Research Symposium explored projects that took wholistic, systems approaches to solving challenges with pest intrusion into leafy greens fields, pathogen transference on co-managed farms and the impact of traits associated with concepts of soil health on pathogen persistence. It also examined Cyclospora presence in the irrigation canal systems in the Yuma, AZ production region (Key Learnings Session III).
Session 4 featured the use of genomics and metagenomics to address challenges in identifying new or revisited indicators and index testing-targets of human viral pathogens that may ultimately be used in the produce industry, the distribution and relatedness of Listeria species in the U.S., and the use of that information to better understand source-risk related to facilities and product, identification of competitors of Listeria monocytogenes that might control that organism in composts, and build our knowledge base of bacterial pathogen persistence and rates of genetic diversification in the Yuma and Salinas vegetable production regions (Key Learnings Session IV).
Session 5 featured research describing the “die-off” rates of human pathogens in agricultural water from three locations around the world, the persistence of pathogens in shade-house production environments, pathogen persistence in wash water systems and the potential role
of damaged cells to contaminate washed products, the efficacy of irrigation water sanitation and the potential role of sediments in canal systems as reservoirs of human pathogens (Key Learnings Session V).
A paper has been published on “Environmental Drivers for Persistence of Escherichia coli and Salmonella in Manure-Amended Soils: A Meta-Analysis” by Dao Tran and colleagues at the ARC Training Centre for Food Safety in the Fresh Produce Industry.
The paper, which appeared in the Journal of Food Protection in July, examines 42 primary research studies on pathogen persistence from manure-amended soils, and concludes that “Based on the significant variation observed among individual field studies, it is unlikely the risks associated with the use of manure amendments containing high levels of enteric bacterial pathogens (such as in raw manure) in soils may be solely managed by a uniform exclusion period. Management of the risks associated with the use of soils amended with raw manures is best achieved through risk-based approaches incorporating differences in climate, soil management, and initial levels of bacteria during application.”
While it is recommended that only certified composted organic amendments are used in the production of fresh produce, the message is clear: risk-based approaches taking into account local environmental factors must be used by growers for determining appropriate exclusion periods after using untreated manures. More here.
Food Safety News: The source of a national Yersinia outbreak in recent weeks in Norway that affected 23 people is believed to have been salad with spinach or baby spinach.
The Norwegian Institute of Public Health (Folkehelseinstituttet) said the Yersinia enterocolitica O3 outbreak was considered to be over.
Fresh Plaza: The consumption of raspberries, blackberries, and blueberries has increased worldwide in recent years because these fruits are considered an important source of antioxidant compounds. Unfortunately, consumption of berries is associated with a risk of foodborne parasites, such as Cyclospora cayetanensis.
In the USA and Canada, many cyclosporiasis cases have been linked to consumption of berries, while at the farm level, the presence of this human pathogen in berries is directly associated with the presence of the parasite in soil. For these reasons, it is fundamental that producers monitor the presence of this pathogen on farms and packing facilities.
Conventionally, detection of C. cayetanensis in clinical and environmental samples is based on identification of oocysts by microscopy, following modified acid fast staining or by UV-light autofluorescence under ultraviolet, this technique is time-consuming, non-specific, and lacks sensitivity. To overcome these issues, food producing industry requires a molecular method able to detect a low oocyst concentration (40–1500 oocyst per gram) as found in food and environmental samples. More.
The team from the ARC Training Centre for Food Safety in the Fresh Produce Industry has published a review paper in Critical Reviews in Food Science and Nutrition on norovirus and Hep A in berries. Dr Hayriye Bozkurt, Dr Kim-Yen Phan-Thien, Dr Floris van Ogtrop, A/Prof Tina Bell and Prof Robyn McConchie co-authored “Outbreaks, occurrence, and control of norovirus and hepatitis a virus contamination in berries: A review”. The review found that inadequate handler hygiene was the predominant source of pre- and post-harvest contamination, but that the current industrial processing methods (freezing, storage and washing) provided limited efficacy in reducing viral load. They recommended key interventions in personal and environmental hygiene and the development of alternative processing technologies to induce sufficient viral inactivation in berries while maintaining sensory and quality attributes.
Along with feedlot dust blowing in the wind and surface irrigation water flowing adjacent to feedlots, flies captured in leafy greens plots near feedlots are capable of transferring E. coli from animal operations to produce fields.
Set for publication in August in the “Journal of Food Protection,” new research from a team of experts links contamination of leafy greens with E. coli from concentrated animal feeding operations (CAFOs), also referred to as feedlots, via “pest flies.”
“Most fly isolates were the same predominant pulsed-field gel electrophoresis types found in feedlot surface manure and leafy greens, suggesting a possible role for flies in transmitting E. coli O157:H7 to the leafy greens,” according to the research abstract.
Research conducted in 2010 found that Listeria monocytogenes was not predominantly spread by water and chicken manure, two common farm inputs in Australian vegetable farming. It is however more prevalent in summer and in particular in Victoria.
Silage and baled hay produced high numbers of L. monocytogenes which are fed to and ingested by ruminants (cows, sheep, goats). This issue with this feed is that it passes through the animals usually without causing infection to them and becomes trapped within dust when the faeces become dry in hot weather.
The dust carrying the L. monocytogenes can then settle on and contaminate vegetables after being blown large distances by strong winds. Leafy vegetables (eg. curly parsley) can trap dust more effectively and show higher levels of detection than smooth leaf vegetables, such as cos lettuce.
A project recommendation is that intensive livestock operations (feedlots) and grazing cattle, sheep and goats should be kept as far from vegetable production as possible and particularly in the direction of prevailing summer winds.