Listeria Pathogen Can Be Fatal

Listeria monocytogenes bacteria can cause a potentially fatal disease in people with vulnerable immune systems. Listeria infection is the third leading cause of death from food poisoning in the United States. About 1,600 people get sick from Listeria each year and about 260 die. ¹ A number of food borne outbreaks in recent years have been attributed to Listeria. In 2016, a total of 358 frozen food products were recalled amid a Listeria outbreak that hit at least three states. ² In 2011 according to the Centers for Disease Control and Prevention (CDC), 146 people in 28 states were infected, 30 people died, and one person miscarried from cantaloupes contaminated with Listeria. It was the deadliest food borne illness outbreak in over 25 years. FDA officials concluded that new processing equipment and the decision to use a packing and washing technology involving non-chlorinated water were two probable causes of the outbreak. ³

Purdue University research shows that standard cleaning procedures in retail delis may not eradicate Listeria bacteria. A study led by Haley Oliver, assistant professor of food science, found that 6.8 percent of samples taken in 15 delis before daily operation had begun tested positive for Listeria. In a second sampling phase, 9.5 percent of samples taken in 30 delis during operation over six months tested positive for the bacteria. In 12 delis, the same subtypes of the bacteria cropped up in several of the monthly samplings, which could mean that it can persist in growth niches over time. ⁴ Ready-to-eat deli meats are the foods most associated with Listeria which can grow at refrigerator temperatures, unlike Salmonella and E. coli. As Keith Robinson reports, “Stringent control measures and inspections have tampered down the presence of Listeria at meat processing plants, but there are no regulations specific to Listeria for retail delis. Recent risk assessments suggest that up to 83 percent of Listeria cases linked to deli meats are attributable to products contaminated at retail.” ⁴ This ties in with recent experience at Whole Foods. In January 2017 the company shut down all three of its regional kitchens because the FDA discovered a long list of serious violations, some of which resulted in surfaces being contaminated with Listeria. ⁵ Another recent outbreak of Listeria food poisoning is attributed to a creamery in Walton, New York that specializes in unpasteurized milk products. It's not known yet how the cheeses became contaminated—did the milk they were made from (they all were all made from raw milk) already carry the Listeria, or did the contamination occur in the creamery? Further investigation will be necessary to answer this question. ¹

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How to avoid getting infected

Always wash your hands after handling whole melons such as cantaloupe, honeydew and watermelon, and wash or scrub rinds before cutting. Once fruit is cut, eat it promptly or refrigerate the leftovers for no more than a few days. Unlike some other pathogens, Listeria can grow well even at refrigerator temperatures. So federal health officials recommend that anyone who may have contaminated melons throw then out immediately and sanitize thoroughly any surfaces the cantaloupe may have come into contact with. ⁶ Consumers with vulnerable immune systems should buy prepackaged deli meats or heat ready-to-eat meats to 165 degrees F. Meat contaminated with Listeria will not show signs of spoilage, such as sliminess or odor. You can't smell a food and tell it it is safe. ⁴ References

1. Ruth Kava, “Like Russian roulette? Try raw milk.” acsh.org, March 13, 2017
2. “For the record,” Time, June 6, 2016
3. Steve Milloy, “Deadly cantaloupe listeria outbreak blamed on non-chlorinated wash,” junkscience.com, January 10, 2012
4. Keith Robinson, “Study: Listeria pathogen is prevalent, persistent in retail delis,” purdue.edu, February 10, 2015
5. Alex Berezow, “What good is Whole Foods if its food is poisoned?”, acsh.news, January 25, 2017
6. Alice Park,, “Listeria-laced cantaloupe: 6 things you need to know,” healthland.time.com, September 28, 2011