Listeria In Manufactured Food Products; How Does It Happen?
By: Amy Jeanroy
Published: July 31, 2012

As the Gills' Onions Recall unfolds, many questions are left unanswered. How does a company that is one of the largest manufacturers of onions in North America, become contaminated with Listeria? 
First a look at Gill's Onions, from an episode of How It's Made: 

Then, something about Listeria in manufactured foods. According to FoodQuality.com: Listeria is especially difficult because it causes a higher rate of hospitalization than any other foodborne pathogen. 95% of people who are affected by Literiosis are hospitalized. Listeria is the leading cause of death from foodborne pathogens. 
A very simple video covering the symptoms and who is at risk, from JLC Channel:

But Why? Why does Listeria end up in a factory setting? It is basic game of chance. Listeria is very common and can be found almost anywhere. During food processing, vegetables and fruits have many chances to come into contact with the Listeria bacteria. Since many of these manufactured foods are not cooked or pasteurized before eating, it allows the Listeria to be consumed. 
Controlling Listeria in a factory environment can be difficult. If Listeria is not controlled, a biofilm can develop that will not be removed by routine cleaning and sanitization. 
Some simple steps to avoid Listeria are: 
1. Avoid buying ready-to-eat fruits and vegetables. These are foods that have been peeled and cut/washed in a factory setting. Sold as time savers, the truth is, cutting an apple yourself or even an onion, takes less than 30 seconds of your time. 
2. Avoid consuming deli meats and hot dogs raw or cold. Heat these items steaming hot before eating. If this is impractical, avoiding them altogether is another (healthier) option. 
3. Do not believe the hype that RTE will save you time and effort. Cutting two or three onions into bite sized pieces takes mere seconds, and you can then refrigerate your own container of Listeria-free veg for another day. 
4. It almost goes without saying that all fruits and vegetables should be washed before peeling and/or eating. It might be pretty in the plastic bag, but it still needs to be cleaned before putting it in your mouth.