Listeria Hysteria!

Richard Willis

Our connection to food is undeniable and difficult to separate from our daily lives. It sustains our existence and unfortunately its safety for us is taken often time for granted. Safe food is not a safe proposition. An estimated 48 million people come down with food poisoning annually, according to the Centers for Disease Control and Prevention. (Centers for Disease Control and Prevention, 2017) Listeriosis is a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes. An estimated 1,600 people get listeriosis each year, and about 260 die. (Centers for Disease Control and Prevention, 2017) Listeria is the name of a bacteria found in soil and water and some animals, including poultry and cattle. It can be present in raw milk and foods made from raw milk. It can also live in food processing plants and contaminate a variety of processed meats and on hard food contact surfaces. Listeria is unlike many other germs because it can grow even in the cold temperature of the refrigerator. (Food, 2017) Listeria is killed by cooking and pasteurization. Listeria forms microbial populations that makes up a biofilm “community” and are intimately related. Their ability to coexist allows for survival in environments where an individual population may not otherwise be able to survive. (Food, 2017) 

Listeria has been implicated in many outbreaks of food- borne illness, most commonly from exposure to contaminated dairy products and prepared meat products, including turkey and deli meats, paté, hot dogs and seafood and fish. 

(Stearns, 2015) Listeria can be detected in some unlikely environments including shopping carts, meet slicers, even on the bottom of shoes, the bacteria has been observed to thrive. In one European city, shoes sampled at Christmas markets showed the highest Listeria spp. and L. monocytogenes prevalence of 80% (4/5) and 40% (2/5), respectively. With regard to shoe type, Listeria spp. detection rates were 14.3% (3/21; winter boots), 13.3% (2/15; hiking boots), sport shoes (5.9%; 2/34) and brogues (5.1%; 4/79). No Listeria spp. were found on shoe soles that had smooth treads (0/76), while Listeria spp. were detected on 19.5% (8/41) of medium depth tread shoe types and on 9.4% (3/32) of deep tread shoes. These data suggest that soil environment is still one of the most important reservoirs for the foodborne pathogen L. monocytogenes. (D. Schoder, 2015). Cantaloupes and other melons can pick up the bacteria. What’s more, any fruit that is sprayed or washed with water that is contaminated with listeria will be contaminated as well. Luckily, listeria can be found just on the outside of any fruit but it does not penetrate through its flesh. (New Health Advisor, 2014)Vegetables grown in the soil such as squash, potatoes, carrots, and beets may contain listeria. Vegetables are the healthiest foods in your diet, so it is unwise to avoid such vegetables; instead, you can wash them thoroughly before cooking and peel where appropriate. Wash vegetables before and after peeling because some bacteria may be transferred to your hands as you peel. (New Health Advisor, 2014) Listeria can grow in aerobic (with oxygen) and anaerobic (without oxygen); smoked seafood, preserved fish, and raw seafood are also highly likely to be contaminated with listeria bacterium.

Centers for Disease Control and Prevention. (2017, June 29). Listeria(listeriosis). Retrieved September 2017, from Listeria: Commonly asked questions:

D. Schoder, A. K.-B. (2015, May 21). Urban Prevalence of Listeria spp. and Listeria monocytogenes in Public Lavatories and on Shoe Soles of Facility Patrons in the

European Capital City Vienna. Zoonoses and the public health, pp. 179–186.

Food (2017, September 5). Listeria. Retrieved September 2017, from Listeria:

New Health Advisor. (2014). Where Does Listeria Come From? Retrieved September 5, 2017, from New Health Advisor: Listeria-Come-From.html

Stearns, D. (2015, April 11). All You Need to Know About Listeria. Food Poison Journal.

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