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Cyclospora Outbreak Highlights Differing Epidemiology Philosophies

As state and federal officials continue working to pinpoint the source of the June Cyclospora outbreak that sickened at least 275 people in the Midwest, one prominent epidemiologist has criticized the investigation’s speed and effectiveness.

Given the relatively large number of people sickened, the outbreak should have been solved “weeks ago,” according to Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota and former state epidemiologist of Minnesota.

Osterholm told Food Safety News that he fears investigators at the state and federal level are taking their time with the investigation because the outbreak appears to have ended. All of the reported illnesses began in mid-to-late June or the first days of July, suggesting that the cause of the outbreak was likely a fresh produce item that had since expired and is no longer on the market.

But Osterholm said that a lull in cases does not necessarily mean an outbreak doesn’t pose any more threat.

“We’ve had outbreaks in the past when a contaminated item comes out of the farm and it ends, but then a second product is harvested and causes additional illnesses,” he said.

Osterholm’s criticism highlights the difference in philosophies on epidemiological investigations when compared with the viewpoint of Iowa state epidemiologist Dr. Patricia Quinlisk, who said that officials in the affected states are working diligently to find the cause of the complex outbreak.

They have narrowed the likely source down to several vegetables, but they don’t want to risk identifying the wrong product, she told Food Safety News.

One of the biggest hurdles with this investigation, Quinlisk said, is that it’s an outbreak of Cyclospora, a pathogen with a relatively long incubation period of several days to two weeks. Because public health officials rely on meal history interviews to narrow down the suspected source, identifying a source gets increasingly difficult as time passes.

“There’s a great delay between the time people ate the food, got sick, took the time to go to the doctor, got the right laboratory tests performed and reported the infection,” Quinlisk said. “These exposures occurred in early June. If I asked you today what you ate on the 7th of June, you can sort of see the problem. People honestly just don’t remember.”

The other problem with Cyclospora is that it’s associated with fresh produce, and those who eat fresh produce often eat a wide variety of it — possibly in a salad — and not just one or two items. Quinlisk said it will be extremely difficult for investigators to narrow down their list of vegetables much farther, considering all items on it are eaten commonly, and sometimes together in the same meal.

Quinlisk said officials have also performed “cluster investigations,” comparing meal histories of groups of people who dined at the same restaurants or attended the same events around the window of exposure. Still, the investigation is coming up short.

Quinlisk hopes now that the U.S. Centers for Disease Control and Prevention can pool data from Iowa, Nebraska and Texas, the “power in numbers” approach might open up some new leads. Sometimes the epidemiology becomes clearer when investigators see regional eating patterns, she said.

Osterholm, however, said that the amount of time taken to solve the investigation “shouldn’t be tolerated.”

“I’m confident the source should and will be found and we should make sure more products from wherever it came from do not make it into the food system,” he said. “I’m not saying these things because I want to disparage or publicly disagree with any specific public health officials. But those of us who have spent a lifetime in public health can see when an investigation is languishing and not finding answers and it really does potentially pose risks to the public’s health.”

Quinlisk argued that coming out early and naming a possible product without tracing back its origin could harm the entire industry economically and cause unnecessary panic among consumers who weren’t at risk.

“We’re sure the contaminated product is no longer on the market,” Quinlisk said. “But if I were to go to the media and say that cucumbers were the source, even if I explicitly said it was only in June, people would stop eating cucumbers. We don’t want to say something that could be misunderstood or misrepresented.”

© Food Safety News
  • Dan Sowards

    I for one am very tired of hearing comments by Mike Osterholm, a self-appointed expert in epidemiology that somehow gets quoted in almost every foodborne illness outbreak that hits the media. Even though I’m a retired regulatory official after 38 years, it still concerns me that one person, who often does not represent the profession as a whole, is the one who is constantly quoted. Dr. Quinlisk is correct with respect to the issues surrounding the identification of the food that is/was responsible for an outbreak of cyclospora. From a regulatory perspective, I don’t like to see this much time passage. Even so, I also realize what all is involved. Dr. O. knows this as well, but since he’s the media’s darling, he takes on everyone else – to his own discredit as far as I’m concerned. I used to moderate national food safety programs in the past, and I can vouch for the fact that if Dr. Osterholm were on the program, we expected (and received) his late and ostentatious entrance into the meeting. There are other media darlings re food safety who also like to give the impression that our whole system in broken, but since we’re talking about this singular issue, I felt it necessary to provide a different perspective.

    • Le incredible Sulk

      Take home from this comment: I’m a retired regulatory agent who doesn’t like the ‘self appointed expert’ , Dr Osterholm, who by the way, has been an epidemiologist for over 2 decades..

  • Lymebuster

    Ha ! No one has died of it and there are many dying of tick borne pathogens that no one cares about ! 6 year old in NC dies of Rocky Mountain Spotted Fever because the infectious disease monsters have told docs to wait and see if you get a bulls eye rash or symptoms and then we shall treat. ! I can spell murderers can you ? The infectious disease society and their worthless guidelines should be prosecuted for one of the largest crimes against humanity. This cover up of the severity of lyme disease and the myriad of infecting agents that are part of it needs to be exposed. It is time that our governments address this world wide epidemic and get busy together working on a CURE. Vaccines are not going to cover the plethora of pathogens and to think so is a total joke. The unsuspecting public is being bitten every day and it is taking away the our lives and the lives of our children !! This has got to stop and it needs to stop immediately. IDSA does not mention that a raccoon roundworm in your CNS will kill you right away, nor do they mention that people can get Brucella, Tularemia, Leptospirosis, Babesia, Ehrlichia, Anaplasma, Bartonella, Mycoplasmas, Chlamydias, Q fever, all kinds of viruses and parasites from these ticks and that one can remain ill for the rest of their life. We see immune compromisation in lyme patients and they come down with the opportunistic infections of AIDS patients. We are NON HIV AIDS patients just like Asians that have NON HIV AIDS. Where is this coming from and how do we cure people ? That is what we need to address.

  • Pat

    I have been sick with this since June 19th! and am allergic to sulfur and not well yet! lost 17 lbs the 1st week could not get out of bed other and with great difficulty to go to the bathroom! They need to pinpoint the cause!! I am scared to death to eat any fresh fruits or veggies! and don’t know when or if that fear will go away! especially if they don’t find the cause! I save receipts and grocery receipts, I and have pulled my bank receipts to show what when and where I ate to the best of my knowledge. as any one can do! they should have info to find the cause!..

    • apresledeluge

      Yes, they should. They’re stalling, hoping it will subside, and then they’ll say they never did find the cause. Protecting corporations is what they’re doing, so no one sues.