Can you hear me know? The new holiday tradition: Searching for recalls and outbreak information

Longtime friend of the barfblog.com, Michéle Samarya-Timm, health educator at the Somerset County Department of Health (that’s in New Jersey, represent) writes:

Baking pumpkin pies with Aunt Kay’s secret recipe.  Watching Miracle on 34th Street.  Preparing the dining room with the good china.  Diffusing political conversations at the dinner table. 

Some traditions give a sense of warmth, connection, and continuity, and regularly define a family’s holiday. Unfortunately, there is now a need to add an additional tradition to the season – actively checking for foodborne outbreaks and recalls to prevent folks from getting sick.

 Last week, on Tuesday, November 20th at 2pm, (two days before Thanksgiving), the CDC posted a media statement with advice to consumers, restaurants, and retailers: 

 “CDC is advising that U.S. consumers not eat any romaine lettuce, and retailers and restaurants not serve or sell any, until we learn more about the outbreak.”

 The need to release such a notice, right before a major holiday is an unpropitious scenario.  It was also very concerning in its specificity to consumers, retailers and restaurants:

“Wash and sanitize drawers or shelves in refrigerators where romaine was stored.”

Such an alert is most effective if it reaches the intended audiences.   Folks at my holiday table did not hear about the outbreak.  Neither did many local health departments.

Issuing media releases is one way for public health agencies to reach large groups of people. However, distracted by holiday preparations, travel, shopping, family, football and bad weather this advisory was only partially disseminated to the public. A person had to be following news outlets or social media to receive timely notice. I heard about the recall from the woman next to me while I was getting a haircut – not from the CDC or FDA, or any other federal or state agency.   

 It’s disturbing. The CDC could have sent this info directly to local health departments, or notify them that a news release was issued. This was not the first time as a local public health official that I received delayed – or no – official communication about a national foodborne issue.

Local public health professionals rely on communications systems established by federal and state oversight agencies. Most commonly, if a verified or suspect foodborne contamination or outbreak has occurred, the Centers for Disease Control and Prevention (CDC), the U.S. Department of Agriculture, or the U.S. Food and Drug Administration (FDA) will ascertain the appropriateness of information release. If this information is deemed credible, notification is forwarded individually or en masse to state departments of health. The states, in turn, push this information down to local regulators. Each step in the process contains elements that may delay the rapid dissemination of outbreak information. The ability and willingness of all stakeholders to quickly and readily share incident particulars with fellow responding agencies can enhance effectiveness and amplify response efforts.

Electronically sending this advisory directly to the nearly 3,000 local health departments in the US would provide the opportunity for hundreds of health inspectors, health educators, epidemiologists and other to reach the hospitals, food banks, schools, mom and pop establishments and local residents who may not have otherwise received the alert. This was a missed opportunity, and hopefully one that didn’t cause additional cases of illness.

As I’ve written before, coordinated communication strategies within and between public health agencies is less robust than it should be. As a result, state and local public health officials may hear about foodborne disease issues first from other sources, such as the media, word of mouth, public complaints, or the food industry.   

 We need to learn how to communicate better with each other.  Local public health shouldn’t have to keep an eye on the news media, Twitter or Facebook for information pertinent to protecting the people in our jurisdictions.  A multitude of electronic portals exist for purposes of interagency  communication, CDC, FDA, and the public health system should collectively define how pertinent information – such as this romaine advisory – rapidly and routinely gets to the grass roots public health workforce. Continuously improving interagency coordination and communication is a goal that is fundamental to increasing the effectiveness of this nation’s food safety systems. I’m putting this out there, because I’m willing to help with the solution. That way, in future years, I can spend my holidays perfecting Aunt Kay’s pie recipe.

This holiday, I’m thankful for public health influencers and amplifiers – like barfblog.com – that act as outbreak aggregators, and push out info to local public health types like me.   

Some background information and recommendations on this topic can be found in:  Getting the message across: an analysis of foodborne outbreak communications between federal, state, and local health agencies   https://calhoun.nps.edu/handle/10945/49379

FDA’s Gottlieb says Romaine likely came from California (other regions might be off the hook)

Scott Gottlieb, FDA Commissioner took to the Twitter this morning while many were buying TVs and Himalayan salt lamps to talk about the Romaine-linked E. coli O157 outbreak.

I imagine there’s lots of pressure out there to lift the blanket statement from CDC to avoid all Romaine. Especially if the dates of harvest/transition from one location to another make it so it’s not likely that lettuce from certain regions would be linked to the outbreak.

Some sort of identification is great – because how would a consumer know what to ask about or how to figure out the source without it.

 

 

Lettuce is overrated: STEC in Finland

Escherichia coli are Gram-negative rod-shaped bacteria and part of the normal bacterial flora in the gastrointestinal tract, while diarrhoeagenic E. colipathotypes such as Shiga toxin-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) are able to cause gastrointestinal infections [1]. STEC can lead to a severe disease, such as haemolytic-uraemic syndrome (HUS) [2]. The risk of HUS has been related especially to children under 5 years and to elderly people. HUS is characterised by acute onset of microangiopathic haemolytic anaemia, renal injury and low platelet count.

More than 400 STEC serotypes have been recognised, of which the best-known serotype is O157:H7 [1]. The most common non-O157:H7 serotypes causing human infections are O26, O103, O111 and O145 [3]. The virulence of STEC is largely based on the production of Shiga toxin 1 or 2 and is identified by detecting the presence of stx1 or stx2 genes [1,4]. The virulence of EPEC is caused by its capability to form attaching and effacing (A/E) lesions in the small intestine. This capability requires the presence of virulence genes called the locus of enterocyte effacement (LEE) in a pathogenity island (PAI) that encodes intimin [4]. Unlike STEC, EPEC do not produce Shiga toxin. EPEC are divided into two distinct groups by the presence of EPEC adherence factor plasmid (pEAF) expressing bundle-forming pili (BFP), which is a virulence determinant of typical EPEC (tEPEC) [5]. Thus atypical EPEC (aEPEC) are defined as E. coli that produce A/E lesions but do not express BFP. Typical EPEC are best known as a cause of infantile diarrhoea, especially in developing countries [6]. Diarrhoea-causing aEPEC have been shown to be separate group without a close relation to tEPEC, but some serotypes are genetically related to STEC [5]. The pathogenity of aEPEC has been questioned but their involvement with diarrhoeal outbreaks supports the idea that certain strains are diarrhoeagenic [1,7].

Both STEC and EPEC are transmitted through the faecal-oral route, and outbreaks caused by STEC and aEPEC have been described after ingestion of contaminated food or water [7,8]. STEC is common in ruminants and can be found in foods contaminated by ruminant faeces [9]. Most studies on STEC have focused on the serotype O157:H7, but infections and outbreaks caused by non-O157 strains are increasingly reported in Europe and elsewhere [1013]. Atypical EPEC strains are found in animals used for food production, such as cattle, sheep, goat, pig and poultry, in contrast to tEPEC that has been found only in humans [1,14].

Since 1995, clinicians and clinical microbiology laboratories have been obliged to report culture-confirmed STEC infections to the Finnish Infectious Disease Registry (FIDR) maintained by the National Institute for Health and Welfare (THL) in Finland. EPEC infections are not reportable. Since PCR instead of culture became the standard for screening of diarrhoeal patients in 2013, the incidence of reported STEC infections has increased in Finland to 1.2–1.8 per 100,000 population between 2013 and 2015 compared with 0.2–0.6 per 100,000 between 2000 and 2012. From 1997 to 2015, six food- or waterborne STEC outbreaks were detected in Finland (Table 1).

Outbreak of multiple strains of non-O157 Shiga toxin-producing and enteropathogenic Escherichia coli associated with rocket salad, Finland, autumn 2016

15.may.18

Eurosurvelliance, Volume 23, Issue 35, https://doi.org/10.2807/1560-7917.ES.2018.23.35.1700666

Sohvi KinnulaKaisa HemminkiHannele KotilainenEeva RuotsalainenEveliina Tarkka,Saara SalmenlinnaSaija HallanvuoElina LeinonenOllgren JukkaRuska Rimhanen-Finne

https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2018.23.35.170066

Losing California or Arizona: 5 dead, 210 sick from E. coli O157 in lettuce

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.

The FDA’s lack of urgency dumbfounds food safety scientists.

“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.

How the hell would I know? 395 sickened by Cyclospora linked to McDonalds salads

There was this one time, in 2010, I got a phone call at 6 a.m. from the esteemed Michael Osterholm of the Minnesota food safety system.

My wife does a better Minnosotan accent, spending her yute in Albert Lea, eh?

He didn’t like the photo, right, made by the creative couple of Heather and Christian, who used to work in my lab, and opened the conversation with, “How could you print that?”

I said it was an accurate description of what had been publically known about the leafy greens folks since the E. coli O157 spinach outbreak of 2006 (I’m old, waiting for news on the birth of my third grandson).

He then told me he was a consultant for Fresh Express and that they had an excellent food safety system.

I said great, make it public, so people can judge on their own.

Fresh Express has now been linked to 395 cases of Cyclospora through their lettuce served at McDonalds.

U.S. Rep. Rosa DeLauro, D-Conn., is pressing Food and Drug Administration Commissioner Scott Gottlieb for specifics about the investigation of the cyclosporaoutbreak linked to product sold by Fresh Express.

In an Aug. 3 letter her office released to the media, DeLauro said she wrote the letter “out of concern about the current outbreak of cyclosporiasis as well as the transparency and timeliness of your agency’s ongoing investigation.”

“Although once rare in the United States, parasitic outbreaks caused by cyclospora have become more common over the last several decades,” she said in the letter. “Many of these outbreaks have continually been found to be associated with imported fruits and vegetables.”

The recent outbreak is currently responsible for 395 infections — including 16 hospitalizations — across 15 states.

The parasite was first found when the FDA conducted testing on an unused package of Fresh Express salad mix, distributed to a McDonald’s restaurant, containing romaine lettuce and carrots.

The FDA states as of July 13, McDonald’s decided to stop selling the salads at restaurants impacted in Illinois, Iowa, Indiana, Wisconsin, Michigan. Ohio, Minnesota, Nebraska, South Dakota. Montana, North Dakota, Kentucky, West Virginia and Missouri.

In a July 20, statement, McDonald’s said the health and safety of their customers is their top priority.

“The health and safety of our customers and the people who work in McDonald’s restaurants is always our top priority. The additional states identified by the FDA and CDC are among the same states where a week ago we proactively decided to remove our lettuce blend in impacted restaurants and replace it through a different supplier. McDonald’s is committed to the highest standards of food safety and quality and we continue to cooperate and support regulatory and public health officials in their investigations. For those seeking additional information about Cyclospora, we encourage them to visit the CDC and FDA websites.”

Uh-huh.

Cyclospora sucks. My aunt, my mom’s sister, got it in Florida from basil, about a decade ago.

(Doesn’t she look amazing at 80, left.)

Cyclospora isn’t one of those things doctors routinely check for. Then you’re sick for about six weeks until some bright doc figures it out.

The U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) issued an alert to the public on “beef, pork and poultry salad and wrap products potentially contaminated with Cyclospora that were distributed by Caito Foods LLC, of Indianapolis,” Indiana.

USDA also released a public health alert after Indianapolis-based food distributor Caito Foods “received notification from their lettuce supplier, Fresh Express, that the chopped romaine that is used to manufacture some of their salads and wraps was being recalled.”

“Fresh Express follows rigid food safety requirements and preventive controls throughout our supply chain that are carefully designed to mitigate against potential health risks. Working together with public health officials, we are hopeful a definitive source of the outbreak clusters will be identified soon.”

Uh-huh.

Still here, Mike. You can call me in Australia through Google voice 785-532-1925 and tell me what Fresh Express is doing, and why they are importing lettuce in the middle of North American summer.

Norovirus inside leafy greens

Lettuce has been implicated in human norovirus (HuNoV) outbreaks. The virus is stable on the leaf surface for at least 2 weeks; however, the dynamics of virus internalization have not been fully investigated. The purpose of this study was to assess the internalization and distribution of HuNoV and two surrogate viruses, porcine sapovirus (SaV) and Tulane virus (TV), in lettuce and spinach.

Viral inoculations through the roots of seedlings and the petiole of leaves from mature plants were performed, and the viruses were tracked on days 1 and 6 post-root inoculation and at 16 h and 72 h post-petiole inoculation. Confocal microscopy was used to visualize root-internalized HuNoV.

In both lettuce and spinach, (i) HuNoV was internalized into the roots and leaves at similar RNA titers, whereas surrogate viruses were more restricted to the roots, (ii) all three viruses were stable inside the roots and leaves for at least 6 days, and (iii) HuNoV disseminated similarly inside the central veins and leaf lamina, whereas surrogate viruses were more restricted to the central veins. Infectious TV, but not SaV, was detectable in all tissues, suggesting that TV has greater stability than SaV. HuNoV was visualized inside the roots’ vascular bundle and the leaf mesophyll of both plants.

In conclusion, using surrogate viruses may underestimate the level of HuNoV internalization into edible leaves. The internalization of HuNoV through roots and cut leaves and the dissemination into various spinach and lettuce tissues raise concerns of internal contamination through irrigation and/or wash water.

IMPORTANCE Human noroviruses are the leading cause of foodborne outbreaks, with lettuce being implicated in the majority of outbreaks. The virus causes acute gastroenteritis in all age groups, with more severe symptoms in children, the elderly, and immunocompromised patients, contributing to over 200,000 deaths worldwide annually. The majority of deaths due to HuNoV occur in the developing world, where limited sanitation exists along with poor wastewater treatment facilities, resulting in the contamination of water resources that are often used for irrigation.

Our study confirms the ability of lettuce and spinach to internalize HuNoV from contaminated water through the roots into the edible leaves. Since these leafy greens are consumed with minimal processing that targets only surface pathogens, the internalized HuNoV presents an added risk to consumers. Thus, preventive measures should be in place to limit the contamination of irrigation water. In addition, better processing technologies are needed to inactivate internalized viral pathogens.

Tissue distribution and visualization of internalized norovirus in leafy greens

April 2018

Applied Environmental Microbiology, vol.84 no.12

Malak A. EsseiliaTea MeuliabLinda J. Saifa and Qiuhong Wanga

 doi:10.1128/AEM.00292-18

http://aem.asm.org/content/84/12/e00292-18.abstract?etoc

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.

Lettuce grazers rejoice: Consumer Reports says it’s ok to eat romaine lettuce again

Actually, it was the U.S.  Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) who jointly declared an end to the E coli O157 outbreak after nearly two months of investigation. At least 66 people across the U.S and Canada became ill, 22 were hospitalized, and 2 died during November and December, all linked to consumption of romaine lettuce.

Consumer Reports went along for the ride.

What’s been missing is any response from the leafy greens marketing agency types.

Silence – the LGMA cone of silence — is golden, I guess.

CDC announced on January 25, 2018, that this outbreak appears to be over, because the last case became ill on December 12, 2017. This indicates that the food causing illness is no longer available in the marketplace or consumers’ homes.

Although this outbreak appears to be over, the FDA’s outbreak investigation team is continuing to work with federal, state and local partners to determine what leafy greens made people ill, what people ate, where they bought it, and identify the distribution chain — all with the goal of identifying any common food or points where the food might have become contaminated. To date, no common link has been identified.

Because whole genome sequencing showed that the E. coli O157:H7 strain that resulted in the U.S. illnesses was closely related genetically to the strain that caused illnesses in Canada, the FDA and CDC have been in contact with Canadian food safety authorities throughout this outbreak.