CDC closed the iceberg lettuce outbreak on September 11 with a final count of 12,883 illnesses in twenty-one states, at least 570 hospitalizations and two deaths in Michigan, with onsets running from June 14 to August 17. At the peak, before the recall, CDC says more than a thousand infections were occurring in a single day; by August the average was under two a day. Nationally, FDA reports that CDC had counted 19,595 laboratory-confirmed cyclosporiasis cases as of September 8. FDA’s investigation of Taylor Farms de Mexico is still open, and the samples FDA and Mexican officials collected at the growers and the processing plant are pending analysis.
CDC’s final update states the conclusion in its own voice: epidemiologic and traceback data showed that iceberg lettuce from Taylor Farms de Mexico was contaminated with Cyclospora and made people sick. There has never been a positive product test.
The company’s Cyclospora information hub, last modified September 1, answers that. Epidemiologic evidence, it says, is a legitimate tool that can point investigators toward a potential source. Then: it cannot confirm that a specific product caused illness, and that confirmation requires a positive lab test of the product. FDA has no confirmed positive result for any Taylor Farms product as of August 27. The company’s own testing, approximately two thousand samples taken in central Mexico since May, has returned zero positives. The investigation continues, and we will follow the science.
I have been reading company statements in outbreaks for more than thirty years. That paragraph was not drafted by a microbiologist. It reads like a causation defense, or like a communications team looking for a sentence that is technically defensible and lands like exoneration. Here is how you can tell, and here is why it does not survive contact with FDA’s own files.
FDA answered this exact argument in 2020, in writing, to another company
In the 2020 Cyclospora outbreak, FDA and CDC linked bagged salad mixes made at Fresh Express’s Streamwood, Illinois plant to at least 701 illnesses in fourteen states. FDA never found the parasite in a package of salad. It found it in canal water near a farm in south Florida. It then issued a warning letter dated October 20, 2020, and that letter is the best answer anyone has written to the paragraph now sitting on the Taylor Farms website.
Three things in it matter. First, the finding: based on epidemiological and traceback evidence, CDC and FDA determined that the bagged salad mixes made at that facility were the source of the outbreak. Second, the legal consequence: FDA declared the product adulterated under section 402(a)(1) of the Food, Drug, and Cosmetic Act, citing the presence of the parasite in the salad mixes as evidenced by the outbreak itself. Not by a laboratory result. By the outbreak.
Third, and this is the sentence Taylor Farms needs to reckon with. Fresh Express had handed FDA its own negative testing results. FDA wrote back that the company had provided results showing no detection of the parasite in any of its samples and then explained why that did not matter: human pathogens like Cyclosporaare not present in high numbers or homogeneously distributed, and it is not uncommon to see many negatives even when contamination has occurred.
That is FDA, in an enforcement document, telling a salad company that its own negative test results do not mean what the company wants them to mean. Taylor Farms is offering the public the same argument, with a bigger number attached.
The sentence states a legal standard, not a scientific one
Read the verb. The claim is not that the lettuce tested clean. The claim is that nothing can confirm that a specific product caused illness without a positive laboratory test. Causation and confirmation are courtroom words. Outbreak investigators do not use them that way; they identify a vehicle from the evidence that exists — interviews, case-control studies, product tracing, environmental assessment, and laboratory work when there is something left to test.
It also sets a standard higher than any court applies. In civil litigation the question is what more likely than not caused the harm. A rule requiring laboratory confirmation of the food would exceed the burden of proof in every American courtroom.
It appears in no guideline anywhere
The Council to Improve Foodborne Outbreak Response publishes the guidelines state and local health departments use. It is the joint work of the epidemiologists, laboratory directors, environmental health specialists and regulators who do this for a living, with CDC, FDA and FSIS at the table. Chapter 6, Box 6.4, sets out when contaminated food should come off the market, and lists the bases in the alternative, separated by the word OR. The first is specific exposure information linking illness to consumption of that food, even if the pathogen has not been isolated from the food. A definitive laboratory result on a representative sample is listed second, as another way to get there. Section 6.1.1 of the same chapter says waiting for laboratory results may not be necessary before control measures are implemented.
It borrows FDA’s phrase and leaves FDA’s sentence behind
No confirmed positive sample results for product testing is FDA’s wording, from its July 19 false-positive correction. Five days later, on the same advisory page, FDA wrote that the false-positive sample does not change the basis for its ongoing outbreak investigation or the overwhelming epidemiological data supporting the recall, and that traceback and outbreak data continued to converge on shredded iceberg lettuce from Taylor Farms growers in central Mexico. Both sentences are on one FDA page. The hub uses one of them.
It is frozen on a date that has been overtaken
As of August 27, was accurate when written. It is not the current state of the record. FDA updated the advisory on September 11 to 12,883 illnesses in twenty-one states with 570 hospitalizations, and CDC closed the outbreak the same day. The company’s page has not moved since September 1. The number of people has changed; the sentence has not.
It explains the limits of epidemiology and says nothing about the limits of its own testing
Two thousand samples is offered as evidence, and it is the only quantitative claim on the page that no member of the public can check. Samples of what, taken where, when, by whom, by what method, at what sample weight, from which lots? The paragraph that carefully explains what epidemiology cannot do says nothing at all about what its own testing program can do. And then the tagline: we will follow the science arrives one sentence after the page departs from it.
The company did not apply this standard itself, twice
The hub’s own timeline says FDA and CDC brought the traceback and epidemiologic data on July 15, that the company raised scientific questions about the government’s assumptions and methodology on July 15 and 16, and that on July 16 it decided to recall. On July 17 it announced a recall broader than FDA’s traceback — all iceberg sourced and processed through its central Mexico facility — and the page says it did this voluntarily, before FDA asked. There was no positive test on any of those days, and there never has been one. Under the standard the FAQ now proposes, nothing had been confirmed, there was nothing to recall, and the shredded iceberg would have stayed on the line.
The same thing happened in 2013, at the same plant. The company suspended shipments to the United States on August 9, 2013, with no positive product test in existence, and chairman Bruce Taylor told reporters at the time that all our tests have been negative and there was no evidence of Cyclospora in the product. FDA’s environmental assessment, conducted August 12 to 19 at Doctor Mora and five ranches, reports that in the combined sampling of CDC, FDA and Taylor Farms de Mexico, approximately 835 product, water and environmental samples were analyzed, including over 269 human fecal samples collected from on-ranch sanitary facilities. All tested negative except one FDA sample, number 744382, which was inconclusive because the turbidity of the recycled wash water inhibited analysis by the BAM method. The epidemiologic and traceback work still tied the salad mix from that plant to restaurant illnesses in Iowa and Nebraska; CDC’s surveillance summary counts 162 laboratory-confirmed cases among people who ate at two related restaurant chains.
A company that recalls without a positive test, twice, and then tells the public that only a positive test can confirm anything, is not describing how it thinks. It is describing what it would like a jury to believe.
Run the rule backward and almost nothing gets solved
In 1996, 1,465 cases of cyclosporiasis across twenty states, the District of Columbia and two Canadian provinces were associated with Guatemalan raspberries. As the National Advisory Committee on Microbiological Criteria for Foods recounts it, no positive results for the parasite were obtained from any of the environmental samples. In 2013, Texas investigators ran a case-control study on a restaurant cluster and found a matched odds ratio of 19.8 for cilantro, with traceback converging on three suppliers in Puebla. No positive product sample. In 2020, the Fresh Express outbreak above, where FDA found the parasite in a canal and never in a bag. Under the rule this page proposes, none of those vehicles was ever identified and nobody was ever asked to change anything.
A negative result is the expected result, even when the parasite is there
When Canadian federal scientists verified FDA’s BAM 19b method, leafy greens spiked with two hundred oocysts came back positive 93 percent of the time. Leafy greens spiked with ten oocysts came back positive 30 percent of the time. Seven out of ten known-contaminated samples read clean.
Here is the company’s best counterargument, and the produce industry does make it: FDA’s validated method can detect as few as five oocysts in a 25-gram sample. Read the fine print on what that means. Under FDA’s validation guidelines, the limit of detection is the seeding level that produces fractional results — roughly half of known-contaminated samples test positive and half do not. A method’s published floor is the point where it is a coin flip, not the point where it is reliable. Published modeling of FDA’s own validation data puts a number on it: a single 25-gram produce sample reliably detects contamination only above roughly 0.92 oocysts per gram. FDA’s 2013 assessment of this very plant estimates the infectious dose at ten to a hundred sporulated oocysts.
Do that arithmetic. A hundred-gram serving of lettuce carrying fifty oocysts is enough to put somebody in the hospital and sits well below the level at which one sample reliably reports anything. FDA called detection of this parasite complex when it walked back its own July 18 result. That complexity does not run in one direction.
The company’s own trade association says the opposite
The International Fresh Produce Association’s consumer Cyclospora FAQ, last updated September 14, asks whether a specific food was identified and answers yes. Asked whether the recalled product tested positive, it says there were no confirmed positive product results, that the recall and the findings rested on epidemiologic evidence and traceback rather than a positive laboratory test, that produce testing for this parasite has real documented limitations including low sensitivity at low contamination levels, and that the absence of a positive sample did not mean the epidemiological and traceback findings were wrong. That is the produce industry’s own association, writing for consumers, contradicting one of its largest members.
I have heard this argument in a courtroom. It lost.
In October 1998, eleven children were infected with E. coli O157:H7 after a taco lunch at Finley Elementary School in Benton County, Washington. I tried that case. The investigating team, headed by the state epidemiologist for communicable diseases, concluded in writing that because no other common school activity was identified, it was reasonable to conclude a meal served at the school was the likely source, and that the ground beef in the tacos was likely the vehicle. The team called it the most probable source, meaning greater than fifty percent certainty. The jury was asked whether the taco filling contained E. coli and whether it caused the children’s injuries and answered yes to both. The Court of Appeals affirmed on November 21, 2002.
That is what epidemiologic proof looks like when it is tested by cross-examination rather than posted on a website.
Two thousand samples of what?
We know exactly why this question matters, because the 2013 environmental assessment published the breakdown of the last time this company counted its own samples. Of the 793 samples Taylor Farms de Mexico collected across its plant and thirty ranches that year, 273 were sanitary samples, 238 were agricultural inputs, 164 were pre-harvest plant tissue, 47 were environmental, 29 were in-process — and 42 were finished product. A sample count is not a finding. The composition is the finding.
So, publish the composition. None of this is proprietary.
Samples of what. Finished product, incoming raw lettuce, standing crop, irrigation water, wash water, environmental swabs, sanitary facilities. Give the count for each, as the 2013 report did.
By what method. BAM 19b for produce and 19c for water, or an in-house assay? Was it verified for shredded iceberg specifically, and what limit of detection did that verification show?
At what sample size. Twenty-five grams each, or grabs composited into a single test? How many grams were tested against a lot of what weight?
When. The recalled product was distributed June 29 through July 16. How many of the two thousand samples came from lots produced in that window? If the answer is none, say so plainly.
Where. How many ranches, which ones, and how many samples came from the Doctor Mora plant as against the fields that supplied it.
Against what volume. The recall covered 236,192 cases of iceberg lettuce and salad mixes. Two thousand samples against a season of production is a sampling rate, and the company can state it.
Who ran them. The company’s laboratory or an accredited independent one? Will the reports, chain-of-custody records and raw Cq values go to FDA and to the public?
Were there presumptives. Any initial positives retested and reclassified, and any samples where inhibition was detected? FDA disclosed its own reversal within a day. An inhibited sample is not a negative one — FDA sample 744382 is the precedent, at this plant.
And the water. In 2013 this company committed to a sampling program covering products and water as a condition of resuming shipments. Thirteen years on, there is still no public result.
Publish the data or stop citing the number
I have been through every version of this company’s statement since July 17, and through four weeks of the public record since. The two thousand has been carried forward the whole time without ever acquiring a noun.
FDA already wrote the answer, to a different company, six years ago: it is not uncommon to see many negatives even when contamination has occurred. Twelve thousand eight hundred and eighty-three people are in CDC’s final count for this one outbreak. Five hundred and seventy went to a hospital. Two died. They are owed something better than a sentence built to survive a deposition.
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