Nice to see the American Society for Microbiology catch up (nothing personal, Randy, just idle academic chirping, but at least you get paid).
Fresh produce supply chains present variable and diverse conditions that are relevant to food quality and safety because they may favor microbial growth and survival following contamination. This study presents the development of a simulation and visualization framework to model microbial dynamics on fresh produce moving through postharvest supply chain processes.
The postharvest supply chain with microbial travelers (PSCMT) tool provides a modular process modeling approach and graphical user interface to visualize microbial populations and evaluate practices specific to any fresh produce supply chain. The resulting modeling tool was validated with empirical data from an observed tomato supply chain from Mexico to the United States, including the packinghouse, distribution center, and supermarket locations, as an illustrative case study. Due to data limitations, a model-fitting exercise was conducted to demonstrate the calibration of model parameter ranges for microbial indicator populations, i.e., mesophilic aerobic microorganisms (quantified by aerobic plate count and here termed APC) and total coliforms (TC). Exploration and analysis of the parameter space refined appropriate parameter ranges and revealed influential parameters for supermarket indicator microorganism levels on tomatoes. Partial rank correlation coefficient analysis determined that APC levels in supermarkets were most influenced by removal due to spray water washing and microbial growth on the tomato surface at postharvest locations, while TC levels were most influenced by growth on the tomato surface at postharvest locations. Overall, this detailed mechanistic dynamic model of microbial behavior is a unique modeling tool that complements empirical data and visualizes how postharvest supply chain practices influence the fate of microbial contamination on fresh produce.
IMPORTANCE Preventing the contamination of fresh produce with foodborne pathogens present in the environment during production and postharvest handling is an important food safety goal. Since studying foodborne pathogens in the environment is a complex and costly endeavor, computer simulation models can help to understand and visualize microorganism behavior resulting from supply chain activities. The postharvest supply chain with microbial travelers (PSCMT) model, presented here, provides a unique tool for postharvest supply chain simulations to evaluate microbial contamination. The tool was validated through modeling an observed tomato supply chain. Visualization of dynamic contamination levels from harvest to the supermarket and analysis of the model parameters highlighted critical points where intervention may prevent microbial levels sufficient to cause foodborne illness. The PSCMT model framework and simulation results support ongoing postharvest research and interventions to improve understanding and control of fresh produce contamination.
Postharvest supply chain with microbial travelers: A farm-to-retail microbial simulation and visualization framework
American Society for Microbiology, 10.1128/AEM.00813-18
Claire Zoellner, Mohammad Abdullah Al-Mamun, Yrjo Grohn, Peter Jackson, Randy Worobo
Shannon M. Casillas, Carolyne Bennett and Anne Straily of the U.S. Centers for Disease Control write in Morbidity and Mortality Weekly that cyclosporiasis is an intestinal illness caused by the parasite Cyclospora cayetanensis through ingestion of fecally contaminated food or water.
Symptoms of cyclosporiasis might include watery diarrhea (most common), loss of appetite, weight loss, cramping, bloating, increased gas, nausea, and fatigue. Typically, increased numbers of cases are reported in the United States during spring and summer; since the mid-1990s, outbreaks have been identified and investigated almost every year. Past outbreaks have been associated with various types of imported fresh produce (e.g., basil, cilantro, and raspberries) (1). There are currently no validated molecular typing tools* to facilitate linking cases to each other, to food vehicles, or their sources. Therefore, cyclosporiasis outbreak investigations rely primarily on epidemiologic data.
The 2018 outbreak season is noteworthy for multiple outbreaks associated with different fresh produce items and the large number of reported cases. Two multistate outbreaks resulted in 761 laboratory-confirmed illnesses. The first outbreak, identified in June, was associated with prepackaged vegetable trays (containing broccoli, cauliflower, and carrots) sold at a convenience store chain in the Midwest; 250 laboratory-confirmed cases were reported in persons with exposures in three states (illness onset mid-May–mid-June) (2). The supplier voluntarily recalled the vegetable trays (3).
The second multistate outbreak, identified in July, was associated with salads (containing carrots, romaine, and other leafy greens) sold at a fast food chain in the Midwest; 511 laboratory-confirmed cases during May–July occurred in persons with exposures in 11 states who reported consuming salads (4). The fast food chain voluntarily stopped selling salads at approximately 3,000 stores in 14 Midwest states that received the implicated salad mix from a common processing facility (5).
The traceback investigation conducted by the Food and Drug Administration (FDA) did not identify a single source or potential point of contamination for either outbreak.
In addition to the multistate outbreaks, state public health authorities, CDC, and FDA investigated cyclosporiasis clusters associated with other types of fresh produce, including basil and cilantro. Two basil-associated clusters (eight confirmed cases each) were identified among persons in two different states who became ill during June. Investigation of one cluster, for which the state health department conducted an ingredient-specific case-control study, found consumption of basil to be significantly associated with illness. A formal analytic study was not conducted for the other cluster, but all patients reported consuming basil. Three clusters associated with Mexican-style restaurants in the Midwest have resulted in reports of 53 confirmed cases in persons who became ill during May–August. Analytic studies were conducted for two clusters; consumption of cilantro was found to be significantly associated with illness in both. Although a formal analytic study was not possible for the third cluster, all 32 identified patients reported consuming cilantro at the restaurant. FDA traceback of the basil and cilantro from these clusters is ongoing. Additional clusters associated with Mexican-style restaurants were identified in multiple states; but investigations to determine a single vehicle of infection were unsuccessful because of small case counts, limited exposure information, or because fresh produce items (including cilantro) were served as components of other dishes (e.g., in salsa).
Many cases could not be directly linked to an outbreak, in part because of the lack of validated molecular typing tools for C. cayetanensis. As of October 1, 2018, a total of 2,299 laboratory-confirmed cyclosporiasis cases† have been reported by 33 states in persons who became ill during May 1–August 30 and did not have a history of international travel during the 14 days preceding illness onset. Approximately one third of these cases were associated with either the convenience store chain outbreak or the fast food chain outbreak.
The median patient age was 49 years (range = <1–103 years) and 56% were female (1,288 of 2,285). At least 160 patients were hospitalized; no deaths have been reported.
The 2,299 domestically acquired, laboratory-confirmed cases reported in persons who became ill during May–August 2018 are markedly higher than the numbers of cases reported for the same period in 2016 (174) and 2017 (623). This increase might be due, in part, to changes in diagnostic testing practices, including increased use of gastrointestinal molecular testing panels. CDC is working with state public health partners to determine whether and to what extent changes in testing practices might have contributed to increased case detection and reporting.
Consumers should continue to enjoy fresh produce as part of a well-balanced diet. To reduce risk from most causes of foodborne illness and other contaminants, CDC recommends washing fresh fruits and vegetables with clean running water; however, washing, including use of routine chemical disinfection or sanitizing methods, is unlikely to kill C. cayetanensis. Persons with diarrheal illness that lasts >3 days or who have any other concerning symptoms should see a health care provider if they think they might have become ill from eating contaminated food.
Contributing state and local public health department personnel; Food and Drug Administration
Elizabeth Shogren and Susie Neilson of Reveal write that William Whitt suffered violent diarrhea for days. But once he began vomiting blood, he knew it was time to rush to the hospital. His body swelled up so much that his wife thought he looked like the Michelin Man, and on the inside, his intestines were inflamed and bleeding.
For four days last spring, doctors struggled to control the infection that was ravaging Whitt, a father of three in western Idaho. The pain was excruciating, even though he was given opioid painkillers intravenously every 10 minutes for days.
His family feared they would lose him.
“I was terrified. I wouldn’t leave the hospital because I wasn’t sure he was still going to be there when I got back,” said Whitt’s wife, Melinda.
Whitt and his family were baffled: How could a healthy 37-year-old suddenly get so sick? While he was fighting for his life, the U.S. Centers for Disease Control and Prevention quizzed Whitt, seeking information about what had sickened him.
Finally, the agency’s second call offered a clue: “They kept drilling me about salad,” Whitt recalled. Before he fell ill, he had eaten two salads from a pizza shop.
William Whitt and wife Melinda say it is irresponsible for the Food and Drug Administration to postpone water-testing requirements for produce growers. “People should be able to know that the food they’re buying is not going to harm them and their loved ones,” Melinda Whitt said.
The culprit turned out to be E. coli, a powerful pathogen that had contaminated romaine lettuce grown in Yuma, Arizona, and distributed nationwide. At least 210 people in 36 states were sickened. Five died and 27 suffered kidney failure. The same strain of E. coli that sickened them was detected in a Yuma canal used to irrigate some crops.
For more than a decade, it’s been clear that there’s a gaping hole in American food safety: Growers aren’t required to test their irrigation water for pathogens such as E. coli. As a result, contaminated water can end up on fruits and vegetables.
After several high-profile disease outbreaks linked to food, Congress in 2011 ordered a fix, and produce growers this year would have begun testing their water under rules crafted by the Obama administration’s Food and Drug Administration.
But six months before people were sickened by the contaminated romaine, President Donald Trump’s FDA – responding to pressure from the farm industry and Trump’s order to eliminate regulations – shelved the water-testing rules for at least four years.
Despite this deadly outbreak, the FDA has shown no sign of reconsidering its plan to postpone the rules. The agency also is considering major changes, such as allowing some produce growers to test less frequently or find alternatives to water testing to ensure the safety of their crops.
“Mystifying, isn’t it?” said Trevor Suslow, a food safety expert at the University of California, Davis. “If the risk factor associated with agricultural water use is that closely tied to contamination and outbreaks, there needs to be something now. … I can’t think of a reason to justify waiting four to six to eight years to get started.”
The deadly Yuma outbreak underscores that irrigation water is a prime source of foodborne illnesses. In some cases, the feces of livestock or wild animals flow into a creek. Then the tainted water seeps into wells or is sprayed onto produce, which is then harvested, processed and sold at stores and restaurants. Salad greens are particularly vulnerable because they often are eaten raw and can harbor bacteria when torn.
After an E. coli outbreak killed three people who ate spinach grown in California’s Salinas Valley in 2006, most California and Arizona growers of leafy greens signed agreements to voluntarily test their irrigation water.
Whitt’s lettuce would have been covered by those agreements. But his story illustrates the limits of a voluntary safety program and how lethal E. coli can be even when precautions are taken by farms and processors.
Farm groups contend that water testing is too expensive and should not apply to produce such as apples or onions, which are less likely to carry pathogens.
“I think the whole thing is an overblown attempt to exert government power over us,” said Bob Allen, a Washington state apple farmer.
While postponing the water-testing rules would save growers $12 million per year, it also would cost consumers $108 million per year in medical expenses, according to an FDA analysis.
“The Yuma outbreak does indeed emphasize the urgency of putting agricultural water standards in place, but it is important that they be the right standards, ones that both meet our public health mission and are feasible for growers to meet,” FDA spokeswoman Juli Putnam said in response to written questions.
In addition, the FDA did not sample water in a Yuma irrigation canal until seven weeks after the area’s lettuce was identified as the cause of last spring’s outbreak. And university scientists trying to learn from the outbreak say farmers have not shared water data with them as they try to figure out how it occurred and avoid future ones.
A man is accused of rubbing his bare behind on produce at a grocery store in northern Virginia before putting the items back on display.
News outlets report 27-year-old Michael Dwayne Johnson, of Manassas, is charged with indecent exposure and destruction of property. A Manassas police release says an employee on Saturday noticed Johnson grabbing produce, pulling down his pants and rubbing the produce on his behind before putting it back.
It says the store had to destroy several pallets of produce because of Johnson’s actions. A police spokeswoman says the report lists fruit as the ruined produce. Authorities have not released a motive.
As of June 28, 2018 (11am EDT), the U.S Centers for Disease Control (CDC) has been notified of 185 laboratory-confirmed cases of cyclosporiasis in persons who reportedly consumed pre-packaged Del Monte Fresh Produce vegetable trays containing broccoli, cauliflower, carrots, and dill dip. The reports have come from four states.
Seven (7) of these people have been hospitalized, and no deaths have been reported.
Epidemiologic evidenceindicates that pre-packaged Del Monte Fresh Produce vegetable trays containing broccoli, cauliflower, carrots, and dill dip are the likely source of these infections.
Most ill people reported eating pre-packaged Del Monte Fresh Produce vegetable trays containing broccoli, cauliflower, carrots, and dill dip.
Most ill people reported buying pre-packaged Del Monte Fresh Produce vegetable trays containing broccoli, cauliflower, carrots, and dill dip in the Midwest. Most people reported buying the trays at Kwik Trip convenience stores.
The investigation is ongoing. CDC will provide updates when more information is available.
The median illness onset date among patients is May 31, 2018 (range: May 14 to June 9). Ill people range in age from 13 to 79 years old, with a median age of 47. Fifty-seven percent (57%) are female and 7 people have been hospitalized. No deaths have been reported.
Illnesses that began after May 17, 2018 might not have been reported yet due to the time it takes between when a person becomes ill and when the illness is reported.
The U.S. Food and Drug Administration, along with the Centers for Disease Control and Prevention (CDC) and state and local partners, are investigating a multistate outbreak of E. coli O157:H7 illnesses linked to romaine lettuce from the Yuma, Arizona, growing region.
The FDA, along with CDC and state partners, initiated an environmental assessment in the Yuma growing region to further investigate potential sources of contamination linked to this outbreak.
Samples have been collected from environmental sources in the region, including water, soil, and cow manure. Evaluation of these samples is ongoing.
To date, CDC analysis of samples taken from canal water in the region has identified the presence of E. coli O157:H7 with the same genetic finger print as the outbreak strain. We have identified additional strains of Shiga-toxin producing E. coli in water and soil samples, but at this time, the samples from the canal water are the only matches to the outbreak strain.
Analysis of additional samples is still ongoing, and any new matches to the outbreak strain will be communicated publicly and with industry in the region.
Identification of the outbreak strain in the environment should prove valuable in our analysis of potential routes of contamination, and we are continuing our investigation in an effort to learn more about how the outbreak strain could have entered the water and ways that this water could have come into contact with and contaminated romaine lettuce in the region.
As of June 27, the CDC reports that 218 people in 36 states and Canada have become ill. These people reported becoming ill in the time period of March 13, 2018 to June 6, 2018. There have been 96 hospitalizations and five deaths.
The traceback investigation indicates that the illnesses associated with this outbreak cannot be explained by a single grower, harvester, processor, or distributor. While traceback continues, the FDA will focus on trying to identify factors that contributed to contamination of romaine across multiple supply chains. The agency is examining all possibilities, including that contamination may have occurred at any point along the growing, harvesting, packaging, and distribution chain before reaching consumers.
The FDA, along with CDC and state partners, initiated an environmental assessment in the Yuma growing region to further investigate potential sources of contamination linked to this outbreak. To date, CDC analysis of samples taken from canal water in the region has identified the presence of E. coli O157:H7 with the same genetic finger print as the outbreak strain. We have identified additional strains of E. coli in water and soil samples, but at this time, the samples from the canal water are the only matches to the outbreak strain.
The FDA is continuing to investigate this outbreak and will share more information as it becomes available.
“More work needs to be done to determine just how and why this strain of E. coli O157:H7 could have gotten into this body of water and how that led to contamination of romaine lettuce from multiple farms,” said Dr. Scott Gottlieb, commissioner of the U.S. Food and Drug Administration, in a statement.
Foodborne illness resulting from the consumption of contaminated fresh produce is a common phenomenon and has severe effects on human health together with severe economic and social impacts.
The implications of foodborne diseases associated with fresh produce have urged research into the numerous ways and mechanisms through which pathogens may gain access to produce, thereby compromising microbiological safety.
This review provides a background on the various sources and pathways through which pathogenic bacteria contaminate fresh produce; the survival and proliferation of pathogens on fresh produce while growing and potential methods to reduce microbial contamination before harvest.
Some of the established bacterial contamination sources include contaminated manure, irrigation water, soil, livestock/ wildlife, and numerous factors influence the incidence, fate, transport, survival and proliferation of pathogens in the wide variety of sources where they are found. Once pathogenic bacteria have been introduced into the growing environment, they can colonize and persist on fresh produce using a variety of mechanisms.
Overall, microbiological hazards are significant; therefore, ways to reduce sources of contamination and a deeper understanding of pathogen survival and growth on fresh produce in the field are required to reduce risk to human health and the associated economic consequences.
Sources and contamination routes of microbial pathogens to fresh produce during field cultivation: A review
Food Microbiology, vol. 73, pg. 177-208
Oluwadara Alegbeleye, Ian Singleton and Anderson Sant’Ana
Bob Whitaker, Ph.D., chief science and technology officer for Produce Marketing Association (PMA), writes that because it provides inherently healthy, nutritious foods, the fresh produce industry is uniquely positioned to help solve the nation’s obesity epidemic. To do so, consumers must have confidence in the safety of the fresh fruits, vegetables, and nuts they eat and feed their families.
A green row celery field is watered and sprayed by irrigation equipment in the Salinas Valley, California USA
Following a large and deadly outbreak of foodborne illness linked to fresh spinach in 2006, the U.S. produce industry couldn’t wait for government or other direction. After finding significant knowledge gaps and a lack of data needed to build risk- and science-based produce safety programs, the industry created the Center for Produce Safety (CPS) in 2007.
CPS works to identify produce safety hazards, then funds research that develops that data as well as potential science-based solutions that the produce supply chain can use to manage those hazards. While two foodborne illness outbreaks in the first half of 2018 associated with leafy greens demonstrate the industry still has challenges to meet, CPS has grown into a unique public-private partnership that moves most of the research it funds from concept to real-world answers in about a year.
Each June, CPS hosts a symposium to report its latest research results to industry, policy makers, regulators, academia, and other produce safety stakeholders. Key learnings from the 2017 symposium have just been released on topics including water quality, cross-contamination, and prevention. A few highlights from those key learnings are summarized here, and for the full details, you can download the Key Learnings report from CPS’s website.
Know Your Water (we were doing that in 2002, long before youtube existed)
Irrigation water is a potentially significant contamination hazard for fresh produce while it is still in the field. While CPS research has revealed many learnings about agricultural water safety in its 10 years, many questions still remain. Meanwhile, the U.S. Food and Drug Administration (FDA)’s proposed Food Safety Modernization Act (FSMA) water testing requirements—which offers some challenges for producers in specific production regions—recently raised even more questions.
New CPS research illustrates the risks of irrigating with “tail water” from runoff collection ponds. With water becoming a precious resource in drought-stricken areas, the objective was to learn if tail water might be recovered and used for irrigation. We learned that differences among pond sites—for example, water sources, climate, ag management practices—can strongly influence the chemistry and microbiology of the water. Further, water pH can influence disinfection treatment strategies.
CPS research continues to investigate tools for irrigation water testing, looking specifically at sample volumes, and searching for better water quality indicators and indexing organisms including harnessing next-generation DNA sequencing. Following a CPS-organized colloquium on ag water testing in late 2017, FDA subsequently announced it would revisit FSMA’s ag water requirements, and postponed compliance.
Bottom line, CPS research demonstrates that growers must thoroughly understand their irrigation water before they can accurately assess cross-contamination risk. CPS’s findings clearly point to the need to take a systems approach, to understand and control the entire water system to help achieve produce safety. Long term, this may mean prioritizing research into ag water disinfection systems to better manage contamination hazards that can also operate at rates needed for field production. Cross-Contamination Can Happen across the Supply Chain
While conceptually and anecdotally the fresh produce industry knows that food safety is a supply chain responsibility, research is needed that documents the role of the entire supply chain to keep fresh produce clean and safe from field to fork. At the 2017 CPS Research Symposium, research reports were presented focusing on cross-contamination risks from the packinghouse to retail store display.
In the packinghouse, CPS-funded research found that wash systems can effectively control cross-contamination on fruit, when proper system practices are implemented. Post-wash, CPS research involving fresh-cut mangos also demonstrated that maintaining the cold chain is critical to controlling pathogen populations. Across the cantaloupe supply chain, CPS studies show food contact surfaces—for example, foam padding—are potential points of cross-contamination. See the full 2017 Key Learnings report for details, as these brief descriptions only scratch the surface of this research.
CPS studies clearly demonstrate that food safety is a supply chain responsibility—a message that must be internalized from growers and packers to transporters, storages, and retailers to commercial, institutional, and home kitchens. While translating this research into reality will present engineering and operational challenges, our new understanding of produce safety demands it. Verifying Preventive Controls
The produce industry must know that its preventive controls are in fact effective. That said, validation can be tricky. If validation research doesn’t mimic the real world, industry ends up fooling itself about whether its food safety processes work—and the human consequences are real.
Numerous scientists presented research at the 2017 CPS Research Symposium that validates various preventive controls, from heat treating poultry litter to pasteurizing pistachios to validating chlorine levels in wash water systems. Some researchers effectively used nonpathogenic bacteria as a surrogate in their validation studies, while another is working to develop an avirulent salmonella surrogate, and another. Wang used actual Escherichia coliO157:H7 (albeit in a laboratory).
Importantly, CPS research finds that the physiological state of a pathogen or surrogate, and pathogen growth conditions themselves, are critically important to validation studies. Meanwhile, suitable surrogates have been identified for some applications, the search continues for many others.
The research findings described here are just some of the real world-applicable results to emerge from CPS’s research program. To learn more, download the 2017 and other annual Key Learnings reports from the CPS website > Resources > Key Learnings page at www.centerforproducesafety.org.
We were doing these videos in the early 2000s, long before youtube.com existed, and weren’t quite sure what to do with them. But we had fun.
Several outbreaks of foodborne illness traced to leafy greens and culinary herbs have been hypothesized to involve cross-contamination during washing and processing. This study aimed to assess the redistribution of Salmonella Typhimurium LT2 during pilot-scale production of baby spinach and cilantro and redistribution of Escherichia coli O157:H7 during pilot-scale production of romaine lettuce.
Four inoculated surrogate: uninoculated product weight ratios (10:100, 5:100, 1:100, and 0.5:100) and three inoculation levels (103, 101, and 10−1 CFU/g) were used for the three commodities. For each of three trials per condition, 5-kg batches containing uninoculated product and spot-inoculated surrogate products at each ratio and inoculation level were washed for 90 s in a 3.6-m-long flume tank through which 890 L of sanitizer-free, filtered tap water was circulated. After washing and removing the inoculated surrogate products, washed product (∼23, 225-g samples per trial) was analyzed for presence or absence of Salmonella Typhimurium or E. coli O157:H7 by using the GeneQuence Assay.
For baby spinach, cilantro, and romaine lettuce, no significant differences (P > 0.05) in the percentage of positive samples were observed at the same inoculation level and inoculated: uninoculated weight ratio. For each pathogen product evaluated (triplicate trials), inoculation level had a significant impact on the percentage of positive samples after processing, with the percentage of positive samples decreasing, as the initial surrogate inoculation level decreased.
The weight ratio of contaminated: noncontaminated product plays an important role: positive samples ranged from 0% to 11.6% ± 2.05% and from 68.1% ± 33.6% to 100% among the four ratios at inoculation of 10−1 and 101 CFU/g, respectively.
To our knowledge, this study is the first to assess the redistribution of low levels of pathogens from incoming product to leafy greens during processing and should provide important data for microbial risk assessments and other types of food safety analyses related to fresh-cut leafy greens.
Transfer and redistribution of Salmonella typhimurium LT2 and Escherichia coli O157:H7 during pilot-scale processing of baby spinach, cilantro, and romaine lettuce
Journal of food Protection vol.81 no. 6 June 2018
HALEY S. SMOLINSKI,1 SIYI WANG,1 LIN REN,1 YUHUAN CHEN,2 BARBARA KOWALCYK,3 ELLEN THOMAS,3 JANE VAN DOREN,2 and ELLIOT T. RYSER1*
Surveys still suck, but the results of this one generally correlate to what we have found doing 20 years of on-farm food safety with fresh produce growers.
Outbreaks and crisis drive grower food safety concerns, prevention is a hard sell, but we’ve shown it can be done.
Understanding growers’ preferences regarding interventions to improve the microbiological safety of their produce could help to design more effective strategies for the adoption of such food safety measures by growers.
The objective of this survey study was to obtain insights for the design of interventions that could stimulate growers to increase the frequency of irrigation water sampling and water testing to reduce possible microbiological contamination of their fresh produce.
The results showed that price intervention, referring to making the intervention less costly by reducing the price via discounts, is the most effective strategy to change growers’ intentions to increase their frequency of irrigation water testing. Moreover, a sense of urgency affects their intentions to increase the frequency of irrigation water testing.
The findings of this survey support the hypothesis that, to date, safety is not perceived as a quality control issue under normal circumstances, but safety becomes an overriding attribute in a food crisis.
Understanding preferences for interventions to reduce microbiological contamination in Dutch vegetable production
June 2018, Journal of Food Protection vol. 81 no. 6
A. P. M. VAN ASSELDONK,1*L. MALAGUTI,2M. L. H. BREUKERS,1 and H. J. van der FELS-KLERX2,3