AILSA CHANG, HOST:
Health officials have yet to confirm the source of cyclospora in food. It has sickened thousands of people nationwide with diarrhea. The Food and Drug Administration initially said it found the parasite on a sample of lettuce supplied by Taylor Farms. That's the same company that had supplied some Taco Bell restaurants where people said they ate before they got sick. Yesterday, the FDA retracted those test results and said the test was a false positive. So where does that leave consumers now? Well, NPR's Yuki Noguchi joins us now to explain. Hi, Yuki.
YUKI NOGUCHI, BYLINE: Hi, Ailsa.
CHANG: OK. So does this confusion over this discredited test change anything, I mean, practically speaking?
NOGUCHI: Not really. You know, the back and forth, of course, confused a lot of people...
CHANG: Yeah.
NOGUCHI: ...But the FDA's recommendation remains to not eat iceberg lettuce grown or processed by Taylor Farms in Mexico and sold at Taco Bells and some Walmarts. That recommendation is based only on interviews done with sick people, many of whom had eaten the lettuce or had eaten at Taco Bell. And testing is still ongoing, by the way. The FDA says it's also testing produce at the southern border now to check for cyclospora. But so far, none of this has turned up any positives.
CHANG: OK. So testing is still ongoing - testing, testing, testing. But thousands of cases, Yuki, of this illness have been reported since May - right? - particularly within five states, including Michigan, which is the epicenter. Is it strange to you that a source has not been identified yet?
NOGUCHI: You know, cyclospora cases are on track to break records this year. But they're pretty common every summer. You know, identifying the source quickly, of course, would help contain an outbreak and perhaps save people from getting sick weeks down the line. But Donald Schaffner, a microbiologist at Rutgers, says these are often separate and unrelated clusters.
DONALD SCHAFFNER: Just because you're sick with cyclospora right now doesn't mean that you're part of this cluster of cases that have an epicenter in Michigan and Ohio. What we see is we see multiple cyclospora cases in this country ranging from May to August. Sometimes we can figure out what's causing it, and sometimes we can't.
NOGUCHI: You know, so that's why we're in this limbo.
CHANG: Frustrating. OK. Well, the company Taylor Farms has already recalled its lettuce. Meanwhile, Taco Bell is not using Taylor Farms as a supplier. So are they still the primary suspected sources right now?
NOGUCHI: Well, that's what FDA officials are still pointing to - Taylor Farms - based on their interviews, again, with customers who've gotten sick. Will we ever find the cyclospora itself on the lettuce? You know, that's not clear. Parasites like cyclospora are hard to genetically test for. And plus, when you're trying to find very small amounts across what might be a huge amount of crop, you know, Schaffner says it's easy for parasites to lurk in untested areas. He also points out that sometimes people are exposed to cyclospora not from food but from drinking or swimming in contaminated water. And he says it's possible that bad water may have been used on a batch of lettuce.
CHANG: That is NPR's Yuki Noguchi. Thank you so much, Yuki.
NOGUCHI: Thank you, Ailsa. Transcript provided by NPR, Copyright NPR.
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