Neither positive sample was lettuce. Both were water.
On 2 October, the FDA reported that it had found Cyclospora in two environmental samples taken during inspections in central Mexico. One sample came from a tank holding outgoing wastewater at the Taylor Farms de Mexico processing facility. The other came from a drainage ditch at an iceberg lettuce grower identified in the FDA's traceback. Iceberg lettuce from that supply chain had been linked to a large multistate outbreak in the United States this summer. The CDC has since declared that outbreak over.
The FDA is careful about what this proves, and so should we be. It says there is currently not enough evidence to conclusively determine how contamination occurred. What the samples show, in its words, is that Cyclospora was present in the environment where the lettuce was grown and processed.
The FDA also reports that genotyping of both samples is complete and that it is still analysing how those results relate to genotyping of patient specimens. This article reflects what had been published as at 5 October 2026, and the investigation may be updated.
This was a US outbreak, and nothing here is a verdict on a company. But a UK site buying leafy greens, or fresh produce of any kind, can learn a great deal from where the parasite turned up.
What makes Cyclospora different
Cyclospora cayetanensis is a single-celled parasite. It causes cyclosporiasis, which brings watery diarrhoea, cramping, fatigue and loss of appetite, often arriving about a week after exposure and sometimes relapsing. It behaves unlike the bacteria most HACCP plans are built around, for three reasons that matter to a food manufacturer.
- It does not grow in food. There is no time and temperature control to apply, because the parasite does not multiply on the product. Contamination is about presence, not growth.
- It is not infectious when freshly shed. Oocysts passed in faeces need days to weeks in the environment to sporulate before they can infect anyone. That is why direct person-to-person spread is unlikely, and why contaminated soil and water are such a concern.
- It survives the sanitisers we rely on. FDA material on cyclosporiasis and fresh produce says the parasite is not reliably removed by rinsing or killed by commonly used chemical sanitisers. Check the current FDA wording when you write this into your hazard analysis.
That last point deserves a moment, because it contradicts a habit. In our experience, some produce sites treat the wash line as their main control. For bacteria it is partly right: sanitiser in the wash water helps limit cross-contamination between batches. For Cyclospora you should not rely on it. A wash line can be validated for bacteria, with tidy chlorine and pH records every shift, and still say nothing about this hazard.
What this means for your hazard analysis
If a hazard cannot be grown out and cannot be washed off, the control has to sit earlier in the chain. For most fresh produce manufacturers that means the control is a combination of prerequisite programmes and supplier controls, not a critical control point at the pack line.
Under Codex HACCP principles, the first job is hazard analysis. Ask three questions for Cyclospora and similar parasites on any imported or grown-to-order produce:
- Is the hazard reasonably likely to occur for this product and origin? Be specific. A leafy green irrigated from surface water is a different case from the same crop irrigated from a protected, tested source. Record the reasoning, not only the score.
- Which control measures actually reduce it? If your honest answer is "we wash it", write down why you believe the wash is effective against this hazard. If you cannot, the control is missing from your plan.
- How do you know the control is working? This is the verification question, and it is where we most often see paperwork fall short. A supplier questionnaire saying water is "controlled" is a statement, not evidence.
The Codex General Principles of Food Hygiene (CXC 1-1969) and the Code of Hygiene Practice for Fresh Fruits and Vegetables (CXC 53-2003) are sound reference points when deciding what to ask growers for.
Water is a route in at more than one stage
The sample locations are the useful detail here. A wastewater tank and a drainage ditch are not on most people's mental diagram of "the water that touches the product". Yet water moves through a produce supply chain in many ways:
- Irrigation and crop protection sprays at the grower
- Drainage around fields, packhouses and yards
- Handwashing and toilet facilities for field and packhouse workers
- Wash, flume and cooling water in the processing facility
- Ice used to chill product
- Wastewater leaving the site, and any route by which it could come back, such as backflow, splash, shared drains or vehicle movements
The samples do not tell us that wastewater or drainage caused this outbreak. The FDA has said it cannot yet say how contamination occurred. What they do show is that the parasite was present on site and at a grower, which is exactly the situation a good water and drainage assessment is meant to anticipate.
For each water point, your documentation should answer four things: what the source is, how it reaches the product or a food contact surface, what you have done to control the risk, and what evidence shows that control is working.
Supplier approval is the control that carries the weight
For fresh produce where the parasite cannot be reliably removed after harvest, the strongest lever is upstream. You do not need to design a grower's filtration system. You do need to know whether the grower has assessed their own irrigation water and what they decided.
When you review a produce supplier, ask for specifics:
- The irrigation water source (surface, borehole, mains, reclaimed) and how it is protected from contamination
- The most recent water assessment and test results, by source and by date, not only a statement that testing is done
- Sanitation facilities in the field and packhouse: how many, how located, how serviced, and who checks them
- Drainage and wastewater management at the packing site, and how it is kept apart from product and food contact surfaces
- What the grower does when a result is unsatisfactory, and how you would hear about it
Do not lean on end-product testing to fill the gap: detecting Cyclospora in food is a specialist method, and a negative result on a small sample cannot stand in for upstream controls. Then close the loop. If a supplier's evidence is thin, record the decision you took and why: extra verification, a conditional approval, a supplier audit, or a change of source. An approval that ignores a known gap is harder to defend to an auditor than a documented decision to accept a managed risk.
What UK sites should take from this
Cyclosporiasis is not a new problem for imported fresh produce, and some of the lettuce, herbs and soft fruit on UK shelves can come from similar growing regions. If you buy fresh produce for further processing or for packing, the practical question is the same as it was before this report: could you show an auditor, today, the water story for your highest-risk supplier?
Here is a one-week task. Pick one produce line. List every point where water touches the product or a food contact surface, and write the source against each one. Then pull the water assessment for one grower supplying that line and check that it names the irrigation source and has verification evidence behind it. Any gap is your next job.
Where SafetyCore fits
SafetyCore does not test your water or audit your growers, and no software should pretend to. What it does is hold the discipline that makes the paperwork stand up.
In SafetyCore, a parasite such as Cyclospora can be captured in Hazard Analysis as a biological hazard and scored on severity and likelihood for the product and origin, so the reasoning is on the record. Water supply, wastewater and drainage sit in your Prerequisite Programmes, linked to the risk assessment that justifies them. When you add a new produce supplier or growing region, you can open a Triggered Review that records the trigger, the sections reviewed and the evidence attached. The Hazard Library holds hazards you can reuse across studies.
None of that cleans a drain or tests a sample. It holds the assessment, the water-point map and the review record, so the evidence is there when an auditor asks.
Final thought
The finding that stands out in this report is not a parasite on a leaf. It is a parasite in a wastewater tank and a ditch. If your hazard analysis stops at the wash line, you have drawn the boundary in the wrong place. Walk the water on your site and your growers' sites before an auditor or an outbreak does it for you.
You can map the water points for one produce line, with the hazard scored and the supplier evidence linked, on the SafetyCore free trial at safetycore.co.uk.
Sources: FDA outbreak investigation page; CDC investigation update; Food Safety News, 2 October 2026.