Caution: Increase in Outbreaks Ahead

If a tree falls in the woods when no one is around, does it still make a sound? A similar question can be asked of foodborne illness: if a food makes someone sick but it isn’t diagnosed or isn’t attributed to a food, does it still count? I’m pretty confident that with the increased use of whole genome sequencing (WGS), we’re going to hear a lot more trees falling when it comes to foodborne disease.

As a scientist, I am enamored with WGS. While I think we need to collect more data to ensure we’re telling the right story, it’s clear that WGS is revolutionizing outbreak investigation. And that is a good thing. However, the unintended consequence could be the misperception by consumers that foodborne outbreaks are increasing and that food is less safe, when we in the industry know that safety has actually increased.

WGS has an unparalleled ability to establish links between food, the environment, and illnesses. When forensic scientists gained the ability to analyze bodily fluids, police were able to close old criminal cases. Similarly, as FDA and CDC (and maybe the food industry) go into their old culture collections and subject old bacterial isolates to WGS, they will likely get new clues when it comes to old cases of foodborne illness.

FDA and CDC estimate that a high percentage of foodborne illnesses can’t be traced back to a food. This means that the outbreaks that we do hear about are just the tip of the iceberg. Historically, these outbreaks probably represented gross failures in the system that impacted large numbers of people. Intuitively, we knew there were probably smaller scale issues that flew under the radar. WGS is sensitive enough to detect these, and detect them quickly. Now, thanks to WGS, the number of cases per outbreak are decreasing as a result of the rapid association between food (or environment) and illness.

This is great news. Fewer illnesses per outbreak is clearly a good thing. The ability of WGS to provide insight on potential causes of illness that occurred years ago can provide closure for victims of foodborne illness and their families, and potentially identify food vehicles that we hadn’t previously associated with foodborne illness. The end result will be that new knowledge will enable us to enact measures to make food safer. But will consumers see it that way?

If we plot the number of outbreaks over time, it appears they are increasing. The public could interpret this as “food is less safe.” Similarly, the ability to identify previously unknown vehicles of foodborne illness could signal to consumers that they need to be concerned about all foods, not just eggs, chicken, and ground beef, which were positioned as the main culprits when I was growing up.

As we uncover more foods associated with foodborne disease, I expect that we’ll find the issues fall into two buckets: issues that are easily avoidable and those that are not. Hopefully the insight gained through WGS also will give clarity to the point within the supply chain where the issue occurred. Within the “easily avoidable” bucket are things related to handwashing and personal hygiene, underprocessing (commercially or in the restaurant or home), postprocess contamination (which should be within the facility’s control), cross contamination in the home or restaurant, etc. But there probably will be situations that challenge food safety professionals to find appropriate mitigations. Products that lack a kill step, such as fresh produce that is grown outside where the climate and ecology constantly challenge farmers, could have low levels of pathogens. Sporadic contamination with low levels of pathogens aren’t associated with a high degree of risk — but nothing is risk free. WGS may bring attention to these presumably rare events.

The consumption of fresh produce is well established as a critical component of a healthful diet. Over the past year I’ve learned that the produce industry, more than any other I have worked with, craves knowledge and adapts practices to continuously improve food safety. Yet I fear that over the next several years we may slide down the hill of public perception. If WGS increasingly links illness with fresh produce items, how will the industry respond? We need to start thinking about a multi-pronged approach focused on communication and research that will be needed to allay consumer concerns about fresh produce safety. I’m not very optimistic about our ability to educate consumers about the concept of risk. So we’ll need to focus efforts on innovative practices to reduce the natural, low-level contamination that can occur and/or significantly reduce or remove pathogens from fresh produce without impacting product quality.

WGS is here to stay, and the data are coming in. We can anticipate some of the results, and we need to be prepared to address the challenges that lie ahead...were always here!