ROSEMONT, IL — Three panelists from two different states discussed the investigations of romaine lettuce outbreaks and generated wide-ranging questions during a session at Food Safety Summit 2020.

For the first time, a summit is a virtual event, out of precautions related to the COVID-19 pandemic. The event, which began Monday, runs through tomorrow and features, among other things, a forum for vendors similar to the traditional trade show plus dozens of live educational sessions.

During a session, Tuesday afternoon three panelists and a moderator talked about specific timelines and investigation methods related to two E. coli outbreaks traced to romaine lettuce this past year. The session, “Foodborne Outbreaks in the News,” was moderated by Laura Gieraltowski, the Lead of the Foodborne Outbreak Response Team in the Outbreak Response and Prevention Branch at the Centers for Disease Control and Prevention. She led the conversation with:

  • Polakshee Gogoi of the Wisconsin Department of Agriculture, Trade and Consumer Protection;
  • Sarah Koske, an epidemiologist in the Enteric and Waterborne Diseases Unit of the Communicable Diseases Epidemiology Section at the Wisconsin Department of Health Services, Division of Public Health; and
  • Kelley Vilen, an infectious disease epidemiologist at the Minnesota Department of Health.

The heavy hitters from disease detective teams, all experts in the field, described activities in the Wisconsin and Minnesota state governments during the discovery, patient identification, and product traceback phases of the outbreaks. Both states initiated outbreak investigations based on cases under their jurisdictions and both outbreaks ultimately became multi-state situations.

Among the details discussed at Tuesday’s live session were various demographic facts collected as part of outbreak investigations. Government agencies at all levels report some such information to the public, but some are kept private to protect patients’ identities. One virtual attendee asked why age ranges and gender percentages are pertinent.

Panel members said one way the age and gender numbers are important in outbreak investigations is that they can direct investigators’ attention toward or away from certain food sources. If high numbers of children are involved, then the contaminated food is probably something that kids routinely eat. 

Also, more women tend to eat a salad than men. Consequently, epidemiologists would likely look harder at the possibility of leafy greens compared to other foods as a source of pathogens if more women were sick. Investigators will sometimes add specific questions to their standard patient interviews depending on what the demographic data suggests.

Questions of a romaine nature
Two of the session attendees submitted questions specifically about romaine. The first asked about the broad challenges of investigating events involving leafy greens. That question is as wide as the sky in Yuma, AZ.

The answer was surprisingly specific.

The panelists agreed that two big impediments to traceback are pre-chopped lettuces and multi-ingredient salads that consist of products from multiple growers and handling by other supply line entities; and consumers’ memory recall regarding specific brands. 

For the romaine outbreaks in 2019 a specific grower, processor or distributor could not be identified, partly because of inconsistent shipping and receiving documentation practices. Consumers’ memories were also somewhat inconsistent because of the variety of products that are similarly packaged, panelists said.

The second romaine question asked during the live session zoomed in on a timely topic — the possible seasonal connection among the outbreaks in recent years. The outbreaks have mostly coincided with the seasonal harvest shifts in the spring and fall. Every year harvest workers shift from California’s Salinas Valley to the Yuma, AZ, growing area and back. The two growing areas provide the United States with fresh lettuces 12 months out of 12.

The panelists discussed how the seasonal harvest schedule is unique each year, with the ending of one area’s bounty most likely overlapping with the beginning of the next in the other area. Short of that, there wasn’t a lot for the panel to say. They said the seasonal nature of the outbreaks is just one of the unknown factors that investigators continually face.

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