Cracking the Code on Food Poisoning

Written by Mildred Monsivais and Edited by Sorina Long

Foodborne illness is a detrimental challenge to public health around the world. 48 million people get sick, 128,000 people get hospitalized, and 3,000 people die every year. Foodborne illness occurs when a certain food contains a harmful bacteria, toxin, virus, or parasite that disrupts the digestive tract. For example, Listeria monocytogenes, a common bacterium in food contamination, is found in several foods like corn that are harvested, prepared, processed, and packed. This is just one type of bacterium out of 250 identified pathogens that adapt to the physical and chemical environment of the gut and cause irritation [1]. There are several reasons why foodborne illness is still an ongoing challenge to global public health. Despite policies and regulations established by the United States Department of Agriculture (USDA) and the Food and Drug Administration (FDA), contamination still occurs in the food production process. 

While food contamination is difficult to completely prevent, the detection of a pathogen during an outbreak can be expedited by whole-genome sequencing. Whole genome wide sequencing (WGS) is a genomic technology that sequences the genetic code to determine an organism’s complete genetic sequence [2]. Throughout the years, WGS has become cheaper and easier to use, making it an effective strategy to detect strains of bacteria that have caused an outbreak. Since each bacterial strain’s genome has a unique order of structural units called nucleotides, WGS can match the sequence found in a bacterial sample to a reference sequence of a known strain. Like using DNA to search for the perpetrator of a crime, WGS uses this unique order of nucleotides to identify the bacteria causing the illness. While different strains can have different DNA sequences, they are still significant similarities between different strains. Because of the similarities between strains, identification of one strain can help identify other strains.

For example, WGS helped crack the outbreak caused by Listeria monocytogenes infection. In April of 2016, CRF Frozen Food of Pasco Washington recalled 43 products of the company’s frozen fruit and vegetable line due to the presence of Listeria [3]. The FDA, and Center for Disease Control and Prevention, identified a Listeria strain in the frozen packaged corn, which was genetically related to eight other infectious Listeria strains [4]. Listeria can be a life-threatening illness because it weakens the immune system and can create pregnancy complications. The Listeria outbreak in Washington resulted in three casualties among the nine people infected, causing CRF Frozen Foods of Pasco to shut down their processing plant in that same month. 

It is important for consumers to be aware of which products have been recalled by the FDA, as not all recalls are published by the press. To learn more about which products have been recalled, visit the FDA Recalls, Market Withdrawals and Safety Alerts page. Being aware of the products that have been recalled can prevent the spread of and unfortunate mortalities caused by food-borne illness, a challenging public health issue. With technology advancing rapidly, WGS has facilitated addressing the serious public health threat of foodborne illness. 

References:

1. Hill Colon, Gahan Cormac G.M. (2014). Listeria monocytogenes: survival and adaptation in the gastrointestinal tract. Front Cell Infect Microbiol, 4:1–2. 
2. “Genome Sequencing.” Genome News Network, J. Craig Venter Institute, 15 Jan. 2003, http://www.genomenewsnetwork.org/resources/whats_a_genome/Chp2_1.shtml. Accessed 12 Feb. 2020.
3. Beach, Coral. “CDC close investigation; warns of ongoing Listeria threat.” Food Safety News, Marler Clark, 15 July 2016, https://www.foodsafetynews.com/2016/07/cdc-closes-investigation-warns-of-ongoing-listeria-threat/. Accessed 12 Feb. 2020. 
4. “Whole Genome Sequencing: Cracking the Genetic Code for Foodborne Illness.” U.S. Food & Drug Administration, United States Government, 23 June 2016, https://www.fda.gov/consumers/consumer-updates/whole-genome-sequencing-cracking-genetic-code-foodborne-illness. Accessed 12 Feb. 2020.