Niche plant foods are often touted for their health benefits, but one that may be less obvious is that they can help prevent outbreaks from mushrooming.
That was the case in a small Salmonella outbreak from late 2020 to early 2021, outlined Thursday in a study published by the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report. The outbreak involved an unusual plant food that carried unusual bacteria. And starting with just two cases, health officials were able to identify the source and push a product recall before standard outbreak measures were enacted, suppressing an outbreak that could have spread across the country.
The food at the center of the outbreak was cashew brie — an alternative to vegan brie — and the first two cases identified were in Tennessee. The two people reported eating the same brand of cashew brie at the same restaurant before getting sick. And clinical isolates found they had the same rare serotype of Salmonella—S. Duisburg. Health officials performed whole-genome sequencing of the offending bacteria and entered them into a national repository of pathogenic isolates collected for disease surveillance. There were three genetically related matches: two isolates from California and one from Florida.
Some initial follow-up determined that one of the California patients also confirmed eating the same brand of cashew brie, while Florida health officials noted that their patient reported following a vegan diet. It was enough to support the early hypothesis that the vegan cheese was the culprit, and state and federal health officials got to work cracking the case.
Dirty nuts
Disease detectives collected 36 samples related to the suspected faux brie: 20 retail samples of the cheese and 16 environmental samples collected from the production facility where the vegan cheese was made. Of the 20 store samples, 19 were found to be infected with Salmonella (95 percent), as well as four of the 16 environmental samples from the manufacturing facility (25 percent). Faced with the overwhelming evidence, cashew brie maker Jule’s Foods has issued a voluntary recall.
The Food and Drug Administration worked with Jule’s on a traceback to determine how the Salmonella sneak into their soft cheese substitute. The ultimate source turned out to be the main ingredient of the product: cashews. The raw cashews used for the cheese have not undergone any “lethal treatment” such as pasteurization or irradiation before processing. The FDA worked with the cashew supplier to resolve this.
While many nuts are sold as “raw” in the US, they are often not completely raw. Instead, they undergo steaming, fumigation, or some other method to kill dangerous pathogens. This isn’t always the case, as evidenced by the cashew brie outbreak, but often it is. For example in 2007, after that Salmonella outbreaks were linked to almonds, the U.S. Department of Agriculture introduced a rule that California almonds — which account for the entire commercial almond supply in the U.S. — must be treated to kill them Salmonella.
Finally with the Salmonella tension related to the cashew brie samples, state and federal health officials identified only 20 cases in four states during the outbreak. Although five people were hospitalized, there were no fatalities.
The health officials noted in the MMWR report that “Rapid detection, investigation and recall of products have prevented additional illnesses, given the detection of Salmonella in 95 percent of cashew brie products collected from retail locations during this study.”
If this happens to be the first you hear about the existence of cashew cheese, you are behind the times. It’s been around for a while – long enough, in fact, to have sparked another small one Salmonella outbreak in 2014. That outbreak was related to another brand of cashew cheese and affected 17 people in three states.