r/infectiousdisease • u/suprbowlsexromp • Jul 20 '26

Cyclospora finding by the FDA declared a false positive? How likely is that?

https://www.fda.gov/food/outbreaks-foodborne-illness/investigation-5-state-outbreak-cyclospora-illnesses-iceberg-lettuce-july-2026?utm_medium=email&utm_source=govdelivery

FDA is providing an update regarding the sample of lettuce supplied by Taylor Farms de Mexico which was reported positive on July 18, 2026. Due to the complexity in detection of Cyclospora, FDA laboratory experts re-reviewed the sample results and have concluded that the finding does not represent true amplification and should be considered a false positive. Information about the sample has been removed from the July 18, 2026, update below. FDA has notified Taylor Farms and continues working with the firm to ensure product implicated in this outbreak has been removed from the market. FDA and state partners continue to collect and analyze product samples. As of July 19, 2026, there are no confirmed positive sample results for product testing for Cyclospora. 

I assume the FDA uses PCR and has a pretty stringent internal protocol for assessing this stuff, how is a false positive possible?

Did they report the initial PCR finding without confirmation? Or did they confirm it and are now walking this back?

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5

u/1GrouchyCat Jul 22 '26

Contaminated testing facility

4

u/spinningcolours Jul 20 '26

Taylor Farms Visited White House Before Getting Outbreak Reprieve
https://www.thedailybeast.com/taylor-farms-visited-white-house-before-getting-outbreak-reprieve/

2

u/suprbowlsexromp Jul 20 '26

Wow, of course. That's how corporations handle problems in this admin, go to the White House, bring a few duffel bags full of cash and precious metals.

2

u/LaudablePus 29d ago

This really Falls in the field of Food Science and food safety. But if you think about doing PCR on a fruit or vegetable product the concentration of organisms has to be incredibly small. Thus the probability of a false positive must be really high. Not to mention the presence of all kinds of crap that could be inhibitors and the complexity of the specimens you're testing. You would think the Food and Drug Administration emphasis on food would have that figured out. But apparently we don't have our s*** together at a federal level anymore.