Update June 27, 2020
On June 26, the
CDC and FDA both released an update on the investigation of a multi-state outbreak of Cyclospora illnesses. Illness onset dates range from May 11 to June 17 and expand across 8 states (AR, IL, IN, IO, KS, MI, MN, MS, NE, ND, SD and WI). At this time there are 206 laboratory confirmed cases with 23 hospitalizations and no deaths.
Epidemiologic and traceback evidence indicates that a bagged salad mix produced by Fresh Express is likely the source of the outbreak. These bagged salad mixes containing iceberg lettuce, carrots and red cabbage produced at a single processing facility as private label SKU’s sold at ALDI, Hy-Vee, Jewel-Osco and Walmart do not explain all of the illnesses. For this reason, the CDC and FDA are working with Fresh Express to investigate other possible products from this facility and trace the specific supplier(s) of the salad components to identify other potential sources of illness. Fresh Express has voluntarily issued a
recall of their Marketside Classic Iceberg Salad mixes. The CDC and FDA maintain their advisory to consumers, retailers and foodservice operators to not eat, sell or serve any of the recalled products. These products are identifiable with a leading “Z” on the printed product package coding information, as pictured here.
While the peak of illnesses may appear to be over, the case counts continue to increase, in part as a consequence of the delays in reporting and entry of information into the CDC reporting system. For example, illness onset cases from June 3rd increased by 9 (60%) since the last update on June 23.
PMA will continue to follow the investigation and provide updates as new information becomes available. Meanwhile, a
CDC Cyclospora fact sheet, an FDA fact sheet and a Blue Ribbon Panel Report provide additional information on testing and validation, preventive measures/controls and root cause analyses that you may find helpful.
Update June 24, 2020
Overall prevalence of Cyclospora in humans is approximately 3.5% worldwide. The infection is more prevalent in countries and areas with lower socioeconomic development. Currently, our knowledge of the prevalence in the U.S. and the Western hemisphere is about 0.3-0.5% of humans. Cyclospora cayetanensis only infects humans, although non-primates can be infected by other Cyclospora sp.
Cyclosporiasis is a nationally notifiable disease; meaning CDC receives periodic reports of cases from states and jurisdictions where the disease is reportable and then analyzes evidence that may link cases into an outbreak. In general, since the prevalence in the U.S. is low, small increases in reported illness draw CDC attention and the generally established seasonality of these spikes, typically in late spring and early summer (there are exceptions in the December to February timeframe), is already a be on the lookout sentinel for public health.
FAQs about the pathogen, including best practices to reduce the likelihood of produce contamination and routes of contamination, are available.
The above information boils down to the fact that Cyclospora is shed with feces, but the pathogen does not follow a typical fecal-oral route of transmission. The non-infectious oocysts, or immature spores, require some time in the environment after shedding to sporulate and become infectious when ingested, typically with food or water. Sporulation timing is much reduced at refrigeration temperatures. Direct person-to-person or person to highly perishable food distributed under refrigeration transmission is unlikely. This known biology has important implications particularly for understanding and investigating root cause towards resolving recent outbreaks associated with domestic produce production.
Cyclospora infections are seasonal. Rainfall, temperature, humidity and perhaps photoperiod could affect the seasonality, which cannot be related to rainfall alone, as there is a marked seasonal variation in very dry environments as well. While highly seasonal, outbreaks spike in warm periods of maximal rainfall in Central America, Jordan, Nepal or China. Infections are more prevalent in the absence of rain, during the drier and hotter months in Peru and Turkey. In India, clinical cases were more frequent in the summer before the rainfall period. Therefore, it is difficult to explain a common factor for the differences observed in seasonality.
The FDA Bacteriological Analytical Manual was updated last year to include methods for the detection and identification of Cyclospora. Detection is based primarily on the TaqMan PCR-based identification of pathogen's DNA in produce washes (oocysts are concentrated using filters). It allows detection of at least 5 oocysts in the sample (fresh and frozen berries were used for protocol validation) with varying levels of confidence at these low levels.
FDA is likely to switch to whole genome sequencing of the mitochondrial genome of the pathogen soon: FDA and CDC peer-reviewed 2020 studies indicate that this approach, coupled with the detection of single nucleotide polymorphisms is more conclusive in epidemiological studies.
Challenges with genomics-based epidemiology
Cyclospora is a eukaryote with a sexual reproduction cycle, which makes DNA-based epidemiological studies less straightforward. A 2019 Oak Ridge study suggests using nuclear and mitochondrial markers in a study that used similarity algorithms. In a validation study using 30 samples, this approach was able to correctly link some cases, but failed with others or was partially consistent with epidemiological data. This study underscores challenges that investigators will face in using genomic data to connect the cases.
We will keep you updated as we learn more about the current Cyclospora outbreak, and as new relevant data emerges.
June 20, 2020
On June 20, the CDC and FDA both announced they are investigating a multi-state outbreak of
Cyclospora illnesses. The illnesses began on dates ranging from May 11 to June 14, 2020. The CDC is reporting 76 cases with 16 hospitalizations and no deaths. The investigation is ongoing and encompasses six midwestern states (IA, IL, KS, MN, MO and NE).
The illnesses are linked to consumption of ALDI Little Salad Bar Brand Garden Salad, Hy-Vee Brand Garden Salad, or Jewel-Osco Signature Farms Garden Salad. The CDC is recommending consumers do not eat and retailers do not sell these brands of bagged lettuce. The CDC and FDA are continuing their investigation into the source of the illnesses.
PMA will continue to follow the investigation and provide updates as new information becomes available.
CDC , an Cyclospora fact sheet FDA fact sheet and a Blue Ribbon Panel Report (co-authored by PMA and industry experts) provide additional information on testing and validation, preventive measures/controls and root cause analyses that you may find helpful.