PMA: Research on produce safety priorities

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.[1]

CPS research continues to investigate tools for irrigation water testing, looking specifically at sample volumes,[2] and searching for better water quality indicators and indexing organisms including harnessing next-generation DNA sequencing.[3] 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.[4] Post-wash, CPS research involving fresh-cut mangos also demonstrated that maintaining the cold chain is critical to controlling pathogen populations.[5] Across the cantaloupe supply chain, CPS studies show food contact surfaces—for example, foam padding—are potential points of cross-contamination.[6] 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[7] to pasteurizing pistachios[8] to validating chlorine levels in wash water systems.[9] 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.[10] 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.

 

Bugs be passed around on leafy greens

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*

https://doi.org/10.4315/0362-028X.JFP-17-420

http://jfoodprotection.org/doi/abs/10.4315/0362-028X.JFP-17-420

Money talks: Safety interventions in Dutch vegetable production

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

https://doi.org/10.4315/0362-028X.JFP-17-106

http://jfoodprotection.org/doi/abs/10.4315/0362-028X.JFP-17-106

Does chlorine make pathogens harder to detect in fresh produce?

The microbiological safety of fresh produce is monitored almost exclusively by culture-based detection methods. However, bacterial foodborne pathogens are known to enter a viable-but-nonculturable (VBNC) state in response to environmental stresses such as chlorine, which is commonly used for fresh produce decontamination.

Here, complete VBNC induction of green fluorescent protein-tagged Listeria monocytogenes and Salmonella enterica serovar Thompson was achieved by exposure to 12 and 3 ppm chlorine, respectively. The pathogens were subjected to chlorine washing following incubation on spinach leaves. Culture data revealed that total viable L. monocytogenes and Salmonella Thompson populations became VBNC by 50 and 100 ppm chlorine, respectively, while enumeration by direct viable counting found that chlorine caused a <1-log reduction in viability. The pathogenicity of chlorine-induced VBNC L. monocytogenes and Salmonella Thompson was assessed by using Caenorhabditis elegans. Ingestion of VBNC pathogens by C. elegans resulted in a significant life span reduction (P = 0.0064 and P < 0.0001), and no significant difference between the life span reductions caused by the VBNC and culturable L. monocytogenes treatments was observed. L. monocytogenes was visualized beyond the nematode intestinal lumen, indicating resuscitation and cell invasion. These data emphasize the risk that VBNC food-borne pathogens could pose to public health should they continue to go undetected.

IMPORTANCE Many bacteria are known to enter a viable-but-nonculturable (VBNC) state in response to environmental stresses. VBNC cells cannot be detected by standard laboratory culture techniques, presenting a problem for the food industry, which uses these techniques to detect pathogen contaminants. This study found that chlorine, a sanitizer commonly used for fresh produce, induces a VBNC state in the foodborne pathogens Listeria monocytogenes and Salmonella enterica. It was also found that chlorine is ineffective at killing total populations of the pathogens. A life span reduction was observed in Caenorhabditis elegans that ingested these VBNC pathogens, with VBNC L. monocytogenes as infectious as its culturable counterpart. These data show that VBNC foodborne pathogens can both be generated and avoid detection by industrial practices while potentially retaining the ability to cause disease.

Viable-but-nonculturable listeria monocytogenes and Salmonella enterica serovar Thompson induced by chlorine stress remain infectious

17 April 2018

American Society for Microbiology, vol. 9 no. 2

Callum J. HighmoreaJennifer C. Warnera*Steve D. Rothwellb, Sandra A. Wilksa, C. William Keevila

doi: 10.1128/mBio.00540-18

http://mbio.asm.org/content/9/2/e00540-18

The produce problem: Ingredient analysis at restaurants in Cyclospora outbreaks

By Sept. 2017, the U.S. Centers for Disease Control reported that almost 1,000 people had laboratory-confirmed cases of cyclosporiasis for the year.

Another banner year for the parasite famously associated with Guatemalan raspberries in 1996.

During July 21–August 8, 2017, the Texas Department of State Health Services (DSHS) was notified of 20 cases of cyclosporiasis among persons who dined at a Mediterranean-style restaurant chain (chain A) in the Houston area. On August 10, 2017, DSHS requested assistance from CDC to support ongoing investigations by the City of Houston Health Department, Harris County Public Health, Fort Bend County Health and Human Services, and Brazoria County Health Department. The objectives of this investigation were to determine the source of the illnesses in the Houston area and to generate hypotheses about the source of the national increase in cyclosporiasis in 2017.

Chain A has four locations in the Houston area and a central kitchen where many dishes are prepared. A case-control study was performed using a menu-specific questionnaire focusing on items containing fresh produce. A confirmed case was defined as laboratory-confirmed Cyclospora infection and clinically compatible illness in a person who ate at any location of chain A during May 28–July 15, 2017. A probable case was defined as diarrhea and at least one additional sign or symptom compatible with cyclosporiasis (e.g., anorexia, abdominal cramping, bloating, myalgia, fatigue, vomiting, or low-grade fever) in a person within 2 weeks after dining at chain A during May 28–July 15, 2017. Controls were identified as either dining companions of case-patients who had no illness or patrons who dined at the same chain A location within 2 days of a case-patient visit and who had no illness. For controls identified by the latter method, contact information was obtained using commercially available databases used by local health agencies in Texas. Three controls per case-patient were recruited.

A total of 22 case-patients (16 confirmed and six probable) and 66 controls were enrolled in the study. Case-patients had a median age of 52 years (range = 29–79 years); 50% were female. Analysis compared menu items consumed by case-patients and controls, followed by ingredient-level analysis. The following ingredients were identified as being significantly associated with illness: green onions (matched odds ratio = 11.3; 95% confidence interval = 2.55–104.68), tomatoes (5.5; 1.2–51.7), red onions (4.7; 1.3–21.0), and cabbage (4.0; 1.1–15.9). When analysis was limited to the 16 confirmed case-patients and their corresponding 48 controls, only green onions remained significantly associated with illness (17.6; 2.5–775.7). Restaurant invoices from chain A were collected for all items identified during the epidemiologic investigation, but efforts to trace any food item to its source were inconclusive. Although the current study identified potential foods associated with illness in Texas, investigators were not able to identify the illness source or confirm whether the patients within the chain A subcluster had consumed a product reported by other ill persons in the United States.

Cyclosporiasis is an intestinal illness caused by the parasite Cyclospora cayetanensis. Since 2013, the United States has experienced annual increases in the incidence of cyclosporiasis incidence during the summer months, with some illnesses linked to imported produce (1–3). Molecular subtyping of Cyclospora is not currently available; therefore, identification of an ingredient associated with a particular illness subcluster might provide information about a source contributing to other cyclosporiasis illnesses. Previous U.S. outbreaks of cyclosporiasis have been linked to fresh produce, such as prepackaged salad mix, raspberries, and cilantro (3,4). Identification of a vehicle for Cyclospora is complicated by the short shelf life of fresh produce as well as the use of potential vehicles such as garnishes or mixtures with other items that could also harbor the parasite. Ingredient-level analysis within restaurant clusters and subclusters therefore remains critical in Cyclospora outbreak investigations.

Notes from the field: Cyclosporiasis cases associated with dining at a Mediterranean-style restaurant chain- Texas 2017

1.jun.18 CDC

Amelia A. Keaton, MD1,2; Noemi Borsay Hall, PhD2,3; Rebecca J. Chancey, MD2,4; Vivienne Heines, MPH3; Venessa Cantu, MPH3; Varsha Vakil, MPH5; Stephen Long, MD5; Kirstin Short, MPH5; Elya Franciscus, MPH6; Natasha Wahab, MPH6; Aisha Haynie, MD6; Laura Gieraltowski, PhD2; Anne Straily, DVM4

https://www.cdc.gov/mmwr/volumes/67/wr/mm6721a5.htm

5 dead, 197 sick from E. coli O157 linked to romaine lettuce

The U.S. Centers for Disease Control reports there are now five people dead and 197 sick from E. coli O157:H7 linked to romaine lettuce.

  • 197 people infected with the outbreak strain of E. coli O157:H7 have been reported from 35 states.
  • 89 people (48%) have been hospitalized, including 26 people who have developed hemolytic uremic syndrome.
  • 5 deaths have been reported from Arkansas (1), California (1), Minnesota (2), and New York (1).
  • Illnesses started on dates ranging from March 13, 2018 to May 12, 2018.
  • Ill people range in age from 1 to 88 years, with a median age of 29.
  • Sixty-eight percent of ill people are female.

The Public Health Agency of Canada has identified people in several Canadian provinces infected with the same DNA fingerprint of E. coli O157:H7.

It takes two to three weeks between when a person becomes ill with E. coli and when the illness is reported to CDC. Most of the people who recently became ill ate romaine lettuce when lettuce from the Yuma, Arizona, growing region was likely still available in stores, restaurants, or in peoples’ homes. Some people who became sick did not report eating romaine lettuce, but had close contact with someone else who got sick from eating romaine lettuce.

According to the U.S. Food and Drug Administration, the last shipments of romaine lettuce from the Yuma growing region were harvested on April 16, 2018, and the harvest season is over. It is unlikely that any romaine lettuce from the Yuma growing region is still available in people’s homes, stores, or restaurants due to its 21-day shelf life.

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 has identified Harrison Farms of Yuma, Arizona, as the grower and sole source of the whole-head romaine lettuce that sickened several people in an Alaskan correctional facility, but has not determined where in the supply chain the contamination occurred.

On May 31, 2018 the FDA released a blog with updated information on the traceback investigation (for additional information, visit FDA Update on Traceback Related to the E. coli O157:H7 Outbreak Linked to Romaine Lettuce).

A listing of 78 outbreaks linked to leafy greens since 1995 is posted here.

121 sick, 52 hospitalized, 14 with kidney failure and 1 death linked to Yuma romaine E. coli outbreak

I’m not sure in what universe, the-growing-area-has-stopped-harvesting is a useful explanation for an outbreak of foodborne illness that has sickened 121 and hospitalized almost 50 per cent.

And this picture from 12 years ago is still apt.

I’ll write a much more scathing indictment of the 10-year-experiment in self-fellatio practiced by the Leafy Greens Marketing Association in my upcoming book, Food Safety Fairy Tales.

For now, let it be known that according to the U.S. Centers for Disease Control, E. coli O157:H7 linked to romaine lettuce has sickened 121 people in 25 states.

52 people have been hospitalized, including 14 people who have developed hemolytic uremic syndrome.

One death was reported from California.

This investigation is ongoing, and CDC will provide updates when more information is available.

The silence from the leafy greens lobby is deafening: A tale of two women with E. coli

A listing of 78 outbreaks linked to leafy greens since 1995 is posted here.

Maggie Menditto, the executive administrator of the McDowell Foundation for social justice, writes in the New York Times that before my illness, I was a healthy 22-year-old just out of college. But at some point, my doctors speculated, I must have eaten leafy greens contaminated by E. coli bacteria.

My mother had driven me to my local emergency room in the middle of the night after several days of unbearable abdominal cramps and a startling amount of blood coming out of new and terrifying places. The doctor on call thought it was probably just a bad case of colitis.

As the sun began to rise, I was asked if I’d like to go home and take Imodium or if I’d like to stay in the hospital. Given the severity of my pain, I was surprised that I was even given a choice. I allowed myself to be wheeled upstairs with a needle in my vein administering a steady stream of antibiotics, a common treatment for colitis.

But that weekend, I took a turn for the worse, throwing up every hour until there was nothing left in my system but sticky green bile. An infectious disease doctor was called in, my stool sample tested, and I was finally given a diagnosis of E. coli infection.

Doctors don’t know for sure how I became infected with E. coli — at the time, last October, the outbreak tied to romaine lettuce was still several months in the future — but we do have some clues. I’m a vegetarian, so we know it didn’t come from eating meat. Although none of my family members got sick, my father also tested positive for E. coli. The only food we remembered sharing was a batch of arugula from a local farmers’ market about five days before I became ill, making it the most likely culprit.

The antibiotics were immediately stopped, as they have been linked to an increased likelihood of developing dangerous complications from the bacterial infection. But by then the signs were already beginning to show. My platelet count was dropping at a dangerous rate, my kidney function had begun to falter. I had developed hemolytic uremic syndrome, a life-threatening complication of E. coli infection.

I was treated to the first ambulance ride of my life to transfer to Georgetown University Hospital, where I would remain hospitalized for the next 33 days.

In the critical care unit, I was strapped into several machines that would monitor my vitals. The next morning, a doctor came in and inserted a temporary access catheter into the right side of my neck. I was wheeled down to a lower level of the hospital for the first of my six plasmapheresis treatments, a particularly draining experience in which blood was removed, cleaned and then returned to my body via a large tube in my neck.

A team of hematologists, nephrologists, infectious disease specialists and a general physician visited every morning. They’d ask, “How are you feeling, Frances?”

Everyone knows me as Maggie, but in an annoying quirk of my hospitalization, my medical records and wristband all bear my legal name, Frances. “One name for each grandmother,” my mom reasoned when my parents decided to christen me Frances Margaret. An unintended consequence of their thoughtfulness is that I have spent much of my life correcting people who called me Frances. “It’s Maggie, short for Margaret, my middle name,” I said.

But in the hospital, it helped to have a second persona. Frances put on a brave face during the hours of treatment in sterilized facilities, while Maggie drew inward, refusing books and music or anything else that reminded me of who I was outside the hospital walls. From where I sat, pinned to machines by the needles in my veins, in a body I hardly recognized, and with a label on my wrist displaying a name that wasn’t mine, I couldn’t be sure that it was me this was really happening to. I listened patiently as doctors and nurses and technicians came into my room to offer Frances their well wishes, draw blood, or discuss what medications she should take or what procedures might make her body strong once more.

During my first week of hospitalization, the kidney doctors debated whether to begin the dialysis process, sticking to the typical “wait-and-see” approach. But by the end of the week there was no question. I had gained 30 pounds from all the excess fluid and could hardly stand up and walk on my own. I began my first of many three-hour-long dialysis treatments, where they siphoned off the liquid, doing the work of my kidneys that I had so long taken for granted.

I had mostly avoided social media since getting sick, but one day, I logged onto Facebook to see that across the country, people I knew and people I didn’t — a pair of girls I once babysat for, a football team in Rhode Island — were praying for Maggie, hoping Maggie pulled through. The more people that worried about me, the sicker I must be, I thought.

The dialysis continued for three weeks with tiny but measurable results. My platelet counts began to climb, and I started to pee again. But it wasn’t enough to impress the nephrologists, who decided to surgically place a catheter in my chest, to both drain and administer fluids.

Doctors began discussing a kidney transplant and temporary home-care dialysis training. I was sent home for a weekend to rest up before my first training for an eventual dialysis machine to be brought to my parents’ house, but we didn’t get that far. I went to bed after dinner and woke up in an ambulance racing back to the hospital I had just left. My blood pressure had begun a dangerous rise as my kidneys began to start working again, and I had the first of three seizures that night.

The next few days are mostly lost from memory, but some hazy images survive. Waking up in a tube to discover I was getting an M.R.I. A nurse delicately pulling glue from my hair from where the technicians had inserted sensors. My hospital bed being wheeled out of the operating room after the catheter was removed from inside my chest. The sharp lines of the white hallway walls, every corner offering a shadowy descent into someone else’s hospital story.

Through my half-closed lids, I see a rare pocket of sunlight at the end of the corridor. Briefly I feel the warmth of its gaze as we trek on through the seemingly endless maze of the hospital’s hallways and locked doors. The dryness in my mouth is the first clue that I’m back in my body, that my kidneys have begun to heal themselves at an admirable pace.

My mom finds me soon after, as I’m attempting to drink water from a clear plastic straw. She reaches out and holds it in place. The nurse comes in to tell us that it all went well, that Frances’s vitals look good, that we’ll be ready to transfer her back upstairs soon.

“She goes by Maggie,” my mom says.

“Oh, I’m sorry,” the nurse says, glancing down at her chart before stepping back into the hall, “Maggie.”

I turn to smile at my mom. It doesn’t matter what they call me anymore. She holds my hand as we’re guided back upstairs to my hospital room for the last time.

Sometimes now, in my apartment, on the train, while walking down a crowded street, I like to run my fingers over the fresh scars lining my collarbone. Now that the toxins have left my system, now that my body has built itself back up, I have only the scars to remind me that Frances was tested, that Maggie survived. That it really happened to me.

Altoona, Penn. Area High School student Mia Zlupko was shocked when doctors told her some scary news.

“All the doctors came in, and it was kind of like a big surprise like ‘It’s E. coli,'” Mia said.

The 16-year-old is a dancer who enjoys eating healthy. It’s not uncommon for her to grab a salad from the store, which is exactly what she did earlier this month. However, after eating it she became sick and was throwing up with abdominal pain.

“It was a scary process and I wouldn’t want to go through it again,” she said. “I know everyone else wouldn’t want to go through it.”

After four days in the hospital no one could figure out what exactly was wrong.

Just as Mia was heading home she learned her diagnosis. A relief for her mom Tina.

“Had we not gone back to the doctor and then gone to the emergency room, she could have gotten much sicker very quickly,” Tina Zlupko explained.

Now the teen is hoping to share an important message with others so no one else has to go through what she did.

“I’m definitely more aware and I want other people to be aware about it,” Mia said.

The CDC advisory now includes chopped and bagged romaine lettuce, as well as whole heads and hearts of romaine lettuce.

So far at least 64 people have been infected in 16 states. Pennsylvania is one place that has been hit the hardest with at least 12 people infected.

Officials think the outbreak is coming from Yuma, Arizona. They warn people not to eat any romaine lettuce unless you know where it’s from.

All the news just repeats itself: Leafy greens in public

In October, 1996, a 16-month-old Denver girl drank Smoothie juice manufactured by Odwalla Inc. of Half Moon Bay, California. She died several weeks later; 64 others became ill in several western U.S. states and British Columbia after drinking the same juices, which contained unpasteurized apple cider — and E. coli O157:H7. Investigators believed that some of the apples used to make the cider might have been insufficiently washed after falling to the ground and coming into contact with deer feces (Powell and Leiss, 1997) not that washing would do much.

Almost 10 years later, on Sept. 14, 2006, the U.S. Food and Drug Administration announced that an outbreak of E. coli O157: H7 had killed a 77-year-old woman and sickened 49 others (United States Food and Drug Administration, 2006). The outbreak ultimately killed four and sickened at least 200 across the U.S. This was documented-outbreak 29 linked to leafy greens, but also apparently the tipping point for growers to finally get religion about commodity-wide food safety, following the way of their farmer friends in California, 10 years later.

In the decade between these two watershed outbreaks, almost 500 outbreaks of foodborne illness involving fresh produce were documented, publicized and led to some changes within the industry, yet what author Malcolm Gladwell would call a tipping point — “a point at which a slow gradual change becomes irreversible and then proceeds with gathering pace” — in public awareness about produce-associated risks) did not happen until the spinach E. coli O157:H7 outbreak in the fall of 2006. At what point did sufficient evidence exist to compel the fresh produce industry to embrace the kind of change the sector has heralded since 2007? And at what point will future evidence be deemed sufficient to initiate change within an industry?

The 1993 outbreak of E. coli O157:H7 associated with undercooked hamburgers at the Jack-in-the-Box fast food chain propelled microbial food safety to the forefront of public awareness, at least in the U.S. (Powell and Leiss, 1997). In 1996, following extensive public and political discussions about microbial food safety in meat, the focus shifted to fresh fruits and vegetables, following an outbreak of Cyclospora cayetanesis ultimately linked to Guatemalan raspberries that sickened 1,465 in 21 U.S. states and two Canadian provinces (U.S. Centers for Disease Control and Prevention, 1997). That same year, Beuchat (1996) published a review on pathogenic microorganisms in fresh fruits and vegetables and identified numerous pathways of contamination.

By 1997, researchers at CDC were stating that pathogens could contaminate at any point along the fresh produce food chain — at the farm, processing plant, transportation vehicle, retail store or foodservice operation and the home — and that by understanding where potential problems existed, it was possible to develop strategies to reduce risks of contamination (Tauxe et al., 1997). Researchers also reported that the use of pathogen-free water for washing would minimize risk of contamination (Suslow, 1997; Beuchat, 1998).

Beuchat and Ryu (1997) reported in a review that sources of pathogenic microorganisms for produce included:

Preharvest

  • Feces
  • Soil
  • Irrigation water
  • Water used to apply fungicides, insecticides
  • Green or inadequately composted manure
  • Air (dust)
  • Wild and domestic animals (including fowl and reptiles)
  • Insects
  • Human handling

Postharvest

  • Feces
  • Human handling (workers, consumers)
  • Harvesting equipment
  • Transport containers (field to packing shed)
  • Wild and domestic animals (including fowl and reptiles)
  • Insects
  • Air (dust)
  • Wash and rinse water
  • Sorting, packing, cutting, and further processing equipment
  • Ice
  • Transport vehicles
  • Improper storage (temperature, physical environment)
  • Improper packaging (including new packaging technologies)
  • Cross-contamination (other foods in storage, preparation, and display areas)
  • Improper display temperature.

kFresh fruits and vegetables were identified as the source of several outbreaks of foodborne illness in the early 1990s, especially leafy greens (Table 1).

Date Product Pathogen Cases Setting/dish State
Apr-92 Lettuce S. enteriditis 12 Salad VT
Jan-93 Lettuce S. Heidelberg 18 Restaurant MN
Jul-93 Lettuce Norovirus 285 Restaurant IL
Aug-93 Salad E. coli O157:H7 53 Salad Bar WA
Jul-93 Salad E. coli O157:H7 10 Unknown WA
Sep-94 Salad E. coli O157:H7 26 School TX
Jul-95 Lettuce E. coli O153:H48 74 Lettuce MT
Sep-95 Lettuce E. coli O153:H47 30 Scout Camp ME
Sep-95 Salad E. coli O157:H7 20 Ceasar Salad ID
Oct-95 Lettuce E. coli O153:H46 11 Salad OH
May-96 Lettuce E. coli O157:H10 61 Mesclun Mix ML
Jun-96 Lettuce E. coli O153:H49 7 Mesclun Mix NY

Outbreaks of foodborne illness related to leafy greens, 1992-1996.

Dave Gombas told an International Association for Food Protection symposium on leafy green safety on Oct. 6, 2006 in Washington, D.C. that if growers did everything they were supposed to do — in the form of good agricultural practices — and it was verified, there may be fewer outbreaks. He then said government needs to spend a lot more on research.

Wow. The same person who has vacillated between the Produce Marketing Association and the U.S. Food and Drug Administration for the past couple of decades (all you critics who complain about folks jumping back-and-forth-and-back as part of a genetically-engineered conspiracy may want to look at the all-natural, all-good-for-ya produce sector) pronounced on grower verification in which nothing has been done.

Since we were on the same panel in Washington, in 2006, I asked Gombas, why is the industry calling for more investment in research about the alleged unknowns of microbial contamination of produce when the real issue seems to be on-farm delivery and verification? Hiding behind the unknown is easy, working on verifying what is being done is much harder.

More calls for research.

Nothing on human behavior in a fresh produce environment.

It’s just another case of saying the right things in public, but failing to acknowledge what happens on individual farms. Verification is tough. Auditing may not work, because many of these outbreaks happened on third -party audited operations. Putting growers in a classroom doesn’t work, and there’s no evidence that begging for government oversight yields a product that results in fewer sick people.

In 1999, several more outbreaks of Shiga-toxin producing E. coli (STEC) were linked to leafy greens (Table 2), and the U.S. group, the United Fresh Fruit and Vegetable Association, developed and published HACCP-based food safety guidelines for industry (United Fresh Fruit and Vegetable Association, 1999).

Date Product Pathogen Cases Setting/dish State
Feb-99 Lettuce E. coli O157:H9 65 Restaurant NE
Jun-99 Salad E. coli O111:H8 58 Texas Camp TX
Sep-99 Lettuce E. coli O157:H11 6 Iceberg WA
Oct-99 Lettuce E. coli O157:H7 40 Nursing Home PA
Oct-99 Lettuce E. coli O157:H7 47 Restaurant OH
Oct-99 Salad E. coli O157:H7 5 Restaurant OR

Table 2. 1999 U.S. outbreaks of STEC linked to leafy greens

By 2000, Rafferty and colleagues demonstrated that E. coli could spread on-farm in plant production cuttings from one contaminated source, magnifying an outbreak to a whole farm (Rafferty et al., 2000). A 2001 outbreak of Shigella flexneri (886 ill) in tomatoes further focused public and scientific attention onto fresh produce.

Solomon and colleagues (2002a) discovered that the transmission of E. coli O157:H7 to lettuce was possible through both spray and drip irrigation. They also found that the pathogen persisted on the plants for 20 days following application and submerging the lettuce in a solution of 200ppm chlorine did not eliminate all viable E.coli O157:H7 cells, suggesting that irrigation water of unknown microbial quality should be avoided in lettuce production (Solomon et al., 2002a). In a follow-up experiment, Solomon and colleagues (2002b) explored the transmission of E. coli O157:H7 from manure-contaminated soil and irrigation water to lettuce plants. The researchers recovered viable cells from the inner tissues of the lettuce plants and found that the cells migrated to internal locations in plant tissue and were thus protected from the action of sanitizing agents. These experiments demonstrated that E. coli O157:H7 could enter the lettuce plant through the root system and migrate throughout the edible portion of the plant (Solomon et al., 2002b). Such results were widely reported in general media.

During this time, several outbreaks of E. coli were again linked to lettuce and salad (Table 3).

Date Product Pathogen Cases Setting/dish State
Oct-00 Salad E. coli O157:H7 6 Deli IN
Nov-01 Lettuce E. coli O157:H7 20 Restaurant TX
Jul-02 Lettuce E. coli O157:H8 55 Bagged, Tossed WA
Nov-02 Lettuce E. coli O157:H7 13 Restaurant IL
Dec-02 Lettuce E. coli O157:H7 3 Restaurant MN

Table 3: Leafy green outbreaks of STEC, 2000 — 2002.

 In 2003, according to Mexican growers, the market impact of an outbreak of hepatitis A traced to exported green onions lasted up to 4 months while prices fell 72 per cent (Calvin et al., 2004). Roma tomatoes were identified as the source of a salmonellosis outbreak that resulted in over 560 cases in both Canada and the US (CDC 2005).

During 2003-2005, several additional outbreaks of E. coli O157:H7 were linked to fresh leafy greens, including one multi-state outbreak involving Dole bagged lettuce (Table 4). 

Date Product Pathogen Cases Setting/dish State
Sep-03 Lettuce E. coli O157:H7 51 Restaurant CA
Nov-03 Spinach E. coli O157:H7 16 Nursing Home CA
Nov-04 Lettuce E. coli O157:H7 6 Restaurant NJ
Sep-05 Lettuce E. coli O157:H7 11 Dole, bagged Multiple

Table 4: Leafy green STEC outbreaks, 2003 — 2005.

During 2005–2006, four large multistate outbreaks of Salmonella infections associated with eating raw tomatoes at restaurants occurred in the U.S., resulting in 459 culture-confirmed cases of salmonellosis in 21 states. Investigations determined that the tomatoes had been supplied to restaurants either whole or precut from tomato fields in Florida, Ohio, and Virginia (CDC, 2006).

Allwood and colleagues (2004) examined 40 items of fresh produce taken from a retail setting in the U.S. that had been preprocessed (including cut, shredded, chopped or peeled) at or before the point of purchase. They found fecal contamination indicators (E. coli, F-specific coliphages, and noroviruses) were present in 48 per cent of samples.

 Researchers in Minnesota conducted a small-scale comparative study of organic versus conventionally grown produce. They found that while all samples were virtually free of pathogens, E. coli was 19 times more prevalent on produce acquired from the organic farms (Mukherjee et al., 2004). They estimated that this was due to the common use of manure aged for less than a year. Use of cattle manure was found to be of higher risk as E. coli was found 2.4 times more often on farms using it than other animal manures (Mukherjee et al., 2004).

On Sept. 14, 2006, the U.S. Food and Drug Administration (2006) issued a public statement warning against the consumption of bagged fresh spinach.

“Given the severity of this illness and the seriousness of the outbreak,” stated Dr. Robert Brackett, Director of FDA’s Center for Food Safety and Applied Nutrition (CFSAN), “FDA believes that a warning to consumers is needed (United States Food and Drug Administration, 2006).”

That is no different from the sometimes conflicting messages coming from FDA today about the E. coli O157:H7 outbreak on lettuce that originated in Yuma, Arizona: these public health folks are figuring it out on the go.

Sean Rossman of USA Today reports today that in the current E. coli O157:H7 outbreak linked to Yuma lettuce, 70% of those who’ve gotten sick are female.

Similarly, when leafy greens were the culprit of an E. coli outbreak last year, 67% of those infected were women or girls. In 2016, females were 73% of those ill from an outbreak in alfalfa sprouts, notes the U.S. Centers for Disease Control and Prevention.

Here are some suggestions:

  • The first line of defense is the farm, not the consumer.
  • All ruminants — cows, sheep, goats, deer — can carry dangerous E. coli like the O157:H7 strain that sickened people in the spinach outbreak, as well as the Taco Bell and Taco Johns outbreaks ultimately traced to lettuce.
  • Any commodity is only as good as its worst grower.

We’ve had a few peer-reviewed thoughts on these topics:

Powell, D.A. and Chapman, B. 2007. Fresh threat: what’s lurking in your salad bowl?. Journal of the Science of Food and Agriculture. 87: 1799-1801.

Implementing On-Farm Food Safety Programs in Fruit and Vegetable Cultivation, Improving the Safety of Fresh Fruit and Vegetables

Luedtke, A., Chapman, B. and Powell, D.A. 2003. Implementation and analysis of an on-farm food safety program for the production of greenhouse vegetables. Journal of Food Protection. 66:485-489.

Powell, D.A., Bobadilla-Ruiz, M., Whitfield, A. Griffiths, M.G.. and Luedtke, A. 2002. Development, implementation and analysis of an on-farm food safety program for the production of greenhouse vegetables in Ontario, Canada. Journal of Food Protection. 65: 918- 923.

A listing of 78 outbreaks linked to leafy greens since 1995 is posted here.

Risk is not low if cause is not known: 5, then 19, now 34 sick and 1 dead sick in E. coli outbreak linked to Edmonton restaurant

If the E. coli-romaine lettuce made it to an Alaskan prison, maybe it made it to an Edmonton restaurant.

Just asking.

According to the Toronto Star, one person has died and more than 30 people have fallen ill following an E. coli outbreak that Alberta Health Services has called “extremely complex” to investigate.

In a statement, AHS says it has expanded its investigation into the source of an outbreak of E. coli, beyond cases directly linked to an Edmonton restaurant late last month.

While 21 of these lab-confirmed cases are linked to Mama Nita’s Binalot restaurant in Edmonton, AHS no longer has public health concerns related to the restaurant.

The number of lab-confirmed cases of E. coli has increased to 34, including 11 patients who have needed hospital care, and one patient who has died likely due to E. coli infection.

“This outbreak is extremely complex, however AHS, in partnership with other provincial and federal agencies, is doing all we can to protect the health of Albertans,” said Dr. Chris Sikora, a medical officer of health in the Edmonton zone, in a statement. “The risk of illness remains very low.”

AHS has not yet identified the source of these cases, but believes they are linked to the initial outbreak.

The risk is not low if the cause is not known.

AHS has worked closely with the owners of Mama Nita’s Binalot since it was identified that a cluster of people with lab-confirmed E. coli ate at the restaurant. AHS says the owners have taken significant steps to manage this issue, including voluntarily closing until AHS was confident the restaurant could reopen without presenting a risk to the public.