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

Leafy greens cone of silence; 33 sickened: environmental investigation of an Escherichia coli O157:H7 outbreak in Oct. 2013 associated with pre-packaged salads

California Department of Public Health (CDPH), Food and Drug Branch (FDB), Emergency Response Unit (ERU) investigated a multi-state foodborne illness outbreak of Escherichia coli O157:H7 (PulseNet Cluster ID 1310CAEXH-1) linked to the consumption of pre-packaged salads purchased in October 2013 at multiple retail locations. The outbreak included a total of 33 ill persons in 4 states; Arizona (1), California (28), Texas (1), and Washington (3). The illness onset dates ranged from October 5, 2013 to November 1, 2013. The case patients had a single matching strain of E. coli O157:H7 (XbaI EXHX01.0589 and BlnI EXHA26.3182).

lettuce.skull.e.coli.O145Initially, two varieties of Trader Joe’s salads were suspected food vehicles in this outbreak. These Trader Joe’s salads were produced by the same manufacturer, Atherstone Foods Inc. in Richmond, CA. As the epidemiological investigation progressed, two additional salads were identified as possibly causing illness.

One of these salads was manufactured by in Oakland, CA, while the other salad was also manufactured by Atherstone Foods Inc., for the Walgreens chain of drug stores. Analysis of the common ingredients among all four salads revealed that romaine lettuce was the only common component. FDB narrowed the traceback to romaine lettuce and determined that a single field of romaine lettuce in Modesto, CA, grown by Ratto Bros. could have been used in the production of all four salads. FDB and the United States Food and Drug Administration (FDA) conducted an environmental investigation at Atherstone Foods, Inc. (DBA: Glass Onion Catering), in Richmond, CA. Seven retain product samples (consisting of the two implicated Trader Joe’s salads) were collected by FDB and tested by the Food and Drug Laboratory Branch (FDLB) in Richmond, CA. These samples were negative for E. coli O157:H7. The inspection at Atherstone Foods, Inc. did not result in any food safety violations or potential areas of cross-contamination. FDB and FDA continued the outbreak investigation at the grower of the suspected romaine. Investigators inspected Ratto Bros. procedures related to growing, handling and transport of the suspect romaine lettuce. Distribution documents, farm conditions, and water systems used by Ratto Bros. were reviewed in detail. Five of 44 environmental samples collected from areas around the implicated ranch were positive for E. coli O157:H7. One of these samples was obtained from a private road while the other four samples were collected on public roads near the implicated field. The positive samples were not a genetic match to the outbreak strain. FDB could not determine the root cause of contamination to the salads implicated in this outbreak. Investigators identified factors during the investigation at the implicated field that could have contributed to contamination of romaine in a farm environment. These potential factors were wind transferring pathogens from contaminated areas to growing fields and farm equipment contaminating crops after using public roads shared with neighboring cattle operations. Ratto Bros. management responded to the Department’s findings by enhancing their current procedures and adopting new procedures in an effort to prevent potential contamination events in the future.

Leafy green cone of silence: lawsuits dismissed against Tanimura & Antle

With different interpretations offered by opposing legal teams, two E. coli-related lawsuits filed by Seattle lawyer Bill Marler against Salinas-based Tanimura & Antle have been dismissed.

lettuce.skull.noroMarler told The Packer both cases had merit and were dismissed for reasons not related to the legitimacy of the cases.

Wesley Van Camp, vice president legal and general counsel for Tanimura & Antle, said the cases illustrated the importance of putting up a rigorous legal fight if there is no clear-cut connection between foodborne illnesses and specific fresh produce. She said the government must investigate to find a link between foodborne illness and specific produce items.’

In Pueblo, Colo., Tanimura & Antle had been named as a third-party defendant in an E. coli food contamination lawsuit, Liebnow vs. Boston Enterprises. The trial, which had been set for June 3, ended when the plaintiff dismissed her lawsuit against Tanimura & Antle, according to a release from the company.

Tanimura & Antle’s legal counsel was present at a mediation of the Colorado case and insisted upon dismissal of all claims against the company and defendants with prejudice, Van Camp said. The company was not a party to the settlement and no confidentiality provisions applied to Tanimura & Antle, she said.

Tanimura & Antle said in the release that a report filed by David Acheson, former associate commissioner for foods at the Food and Drug Administration, was pivotal in the case. Though a state epidemiologist had earlier named Tanimura & Antle as the lettuce supplier in the case, Acheson said in his lengthy deposition that public health officials did not conduct a full traceback of romaine lettuce and therefore could not rule out other sources of exposure. Acheson said FDA officials indicated the agency did not believe there was a compelling case to undertake the traceback on romaine lettuce.

Marler said May 3 that the Colorado case was ultimately dismissed by agreement of both parties through mediation. He said the law firm presented expert testimony that refuted Acheson’s conclusions. Timothy Jones, medical doctor and expert witness for Marler’s plaintiff, said in a report that the 2009 E. coli outbreak that caused ten cases of illness — including then 10-year old Emily Liebnow of Colorado Pueblo, Colo. Victims of the outbreak were identified in six states, including Colorado, Connecticut, Iowa, Minnesota, Missouri and North Carolina, he said. Jones said that evidence makes it “extremely unlikely” that anything other than a widely distributed food product was the source of multiple cases of illnesses caused by the E. coli O157:H7 strain.

spongebob.oil_.colbert.may3_.10-300x234“It is far more likely than not that Emily Liebnow’s infection resulted from consumption of contaminated Romaine lettuce from Tanimura and Antle, served at Giacomo’s restaurant on Sept. 6, 2009,” Jones said in this report.

In California, Marler also filed a motion to dismiss the lawsuit brought by Oroville Bernacki on behalf of his deceased wife Gail Bernacki in the U.S. District Court in Northern California against Tanimura & Antle. Tanimura & Antle’s attorney Gregory Rockwell said the plaintiff would not be able to prove that the E. coli infection resulted from the consumption of the defendant’s product.

Disputing that point, Marler said that the evidence presented in the lawsuit showed a genetic match between the woman’s illness and Tanimura & Antle product in the same time frame. Marler said the case had merit but was dismissed because the elderly plaintiff, a Canadian resident, was in declining health and was not mentally or physically up to litigation.

Iowa, Nebraska link cyclospora outbreaks to packaged salads

I don’t know what it is about some folks from Minnesota; they take any opportunity to lecture the rest of the country – and world – about how they should better investigate foodborne illness.

Amy was born in Albert Lea and I get the same attitude, about spongebob_oil_colbert_may3_103111-300x234other things.

Seriously, it’s not like you grew up with Wayne Gretzky.

But, they’re probably right.

Except this time the real culprit may be the leafy greens cone of silence.

The on-going cyclospora outbreak that has sickened almost 400 Americans in 15 states has been linked by Iowa and Nebraska to “a nationally distributed packaged salad mix.”

Can I buy that at retail? Good branding.

“Our investigation implicated prepackaged, prewashed, salad mix as the cause of this outbreak,” said Nebraska’s chief medical officer, Joseph Acierno, in the online update.

Both Iowa and Nebraska officials said in the online updates that the salad mix contained iceberg and romaine lettuce, carrots and red cabbage, though neither state would name the brand or the lettuce_skull__e_coli__O145_1_story1-300x225producer of the bagged salad mix — and they would not say whether it was an imported or domestic product.

But it wasn’t yet clear whether the packaged salad was linked to other infections in other states, officials with the Food and Drug Administration and the Centers for Disease Control and Prevention said.

Leafy greens cone of silence leads to Canadian lawsuit over E. coli

In a lawsuit filed late last week, attorneys allege that lettuce sold by California-based Tanimura & Antle led to a Canadian woman’s E. coli infection.

The family of a Canadian woman who allegedly died after eating E. coli-contaminated lettuce sold by California-based Tanimura & Antle filed a lawsuit against the company late last week in U.S. District Court for the Northern District lettuce.skull.noroof California (Case No. CV13-02140). The lawsuit was filed by Seattle-based Marler Clark and San Diego-based Gordon & Holmes.

According to the lawsuit, the Canadian Food Inspection Agency (CFIA) isolated E. coli O157:H7 from a sample of Tanimura & Antle Romaine lettuce and issued a “Health Hazard Alert” on August 17, 2012, warning the public not to consume “Wrapped Single Head Romaine”. The agency expanded its notice to include additional lettuce on August 20. The complaint alleges that Gail Bernacki, a Calgary, Alberta resident, consumed the Tanimura & Antle Romaine lettuce and fell ill with an E. coli O157:H7 infection in late August, 2012. The complaint states that Ms. Bernacki was hospitalized for several weeks and did not return to her baseline functional status despite extensive rehabilitation and hospitalization. She passed away on January 16, 2013. Attorneys allege that E. coli O157:H7 bacteria isolated from Ms. Bernacki’s stool during her acute E. coli illness was genetically indistinguishable from bacteria the CFIA had isolated from the Tanimura & Antle Romaine lettuce.

“Although growers of leafy greens have made huge strides in food safety since the E. coli outbreak of 2006, this case shows that there is more to do,” said Marler Clark managing partner, Bill Marler.

A table of leafy green outbreaks is available at http://bites.ksu.edu/leafy-greens-related-outbreaks.

Learning from strawberries, spinach and melons: promote safe food practice before the next outbreak

In 1996, California strawberry growers were wrongly fingered as the source of a cyclospora outbreak that sickened over 1,000 people across North America; the culprit was Guatemalan raspberries.

After losing $15-20 million in reduced strawberry sales, the California strawberry growers decided the best way to minimize the effects of an outbreak – real or alleged – was to make sure all their growers knew some food safety basics and there was some verification mechanism. The next time someone said, “I got sick and it was your strawberries,” the growers could at least say, “We don’t think it was us, and here’s everything we do to produce the safest product we can.”

In Sept. 2006, an outbreak of E. coli O157:H7 killed four and sickened at least 200 across the U.S. This was documented outbreak 29 linked to leafy greens, but 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 2011, Jensen Farms, an eastern Colorado cantaloupe grower produced melons that killed 32 and sickened at least 146 with listeria in 28 states. One grower trashed the reputation of the revered Rocky Ford Melon: plantings this year are expected to be down 75 per cent.

Now the Rocky Ford Growers Association has turned to government-delivered food safety audits rather than third-party audits, and committed to emboss a QR code on every melon it slates for retail sale. This QR code will tell consumers where the melon was grown, harvested, and prepared.

Location doesn’t mean safety. Include the production details.

In Aug. 2011, Oregon health officials confirmed that deer droppings caused an E. coli O157:H7 outbreak traced to strawberries, many sold at roadsides, that sickened 14 people and killed one.

So when NPR asks, Are local salad greens safer than packaged salad greens, it’s the wrong question.

It’s not whether large is safer than local, conventional safer than organic: it’s about the poop, and what any grower is doing to manage the poop. Or risks.

Any farm, processor, retailer or restaurant can be held accountable for food production – and increasingly so with smartphones, facebook and new toys down the road. Whether it’s a real or imaginary outbreak of foodborne illness, consumers will rightly react based on the information available.

Rather than adopt a defensive tone, any food provider should proudly proclaim – brag – about everything they do to enhance food safety. Explanations after the discovery of some mystery ingredient, some nasty sanitation, sorta suck.

Microbial food safety should be marketed at retail so consumers actually have a choice and hold producers and processors – conventional, organic or otherwise – to a standard of honesty. Be honest with consumers and disclose what’s in any food; if restaurant inspection results can be displayed on a placard via a QR code read by smartphones when someone goes out for a meal, why not at the grocery store? Or the school lunch? For any food, link to web sites detailing how the food was produced, processed and safely handled. Manage the poop, manage the risk, brag about the brand.

Market food safety efforts at retail – not in newspapers (do they still exist?)

The California Leafy Greens types got $250,000 to inform (they said educate) Canadian consumers about its food safety mandates.

“We want to gauge the impact of a program like the LGMA on consumer confidence,” said Scott Horsfall, chief executive officer of the Sacramento-based organization.

Mike Hornick of The Packer reports LGMA has already surveyed Canadian consumers, and plans to do so again at the program’s end.

Just 10% of those surveyed said they were aware of the LGMA’s food safety processes, and 56% said they’re concerned about the safety of leafy greens.

“It’s a number that gives us pause, consistent with numbers you see in the U.S.” Horsfall said. “At the end we’ll see if we’ve moved anyone.”