Overview of Leafy Greens–Related Food Safety Incidents with a California Link: 1996 to 2016

Abstract

An increase in the number of foodborne illness outbreaks associated with produce has been noted in the literature, and leafy greens have been the most common produce category associated with these outbreaks. California is the largest leafy greens producer in the United States, and many related foodborne illness incidents were traced to this state. A systematic overview of leafy greens incidents linked to California was conducted by the California Department of Public Health, Food and Drug Branch through analysis of complaints, routine surveillance sampling, disease outbreaks, and investigations covering 1996 to 2016. The goal was to develop a risk assessment tool to modernize emergency response efforts to foodborne illnesses related to leafy greens. A database including environmental, epidemiologic, and laboratory information for each incident was developed, and descriptive analysis was performed to identify trends. In the 21-year period analyzed, 134 incidents were identified, the majority of which were surveillance related. Approximately 2,240 U.S. cases of confirmed illness were reported (298 California cases resulting in 50 hospitalizations). Romaine lettuce and spinach were the most commonly implicated vehicles. The most prevalent hazard type was microbiological, in particular bacterial, specifically associated with pathogenic strains of Escherichia coli. In California, the overview provided the Food and Drug Branch with a platform to (i) enhance its Food Safety Program, Emergency Response Unit, and California Food Emergency Response Team; (ii) assist in more efficient investigation, response, control, and prevention of California-linked foodborne illness incidents; and (iii) identify knowledge gaps and develop effective definitions, procedures, training, guidelines, and policies that will be used to help prevent future outbreaks. Outcomes provide insight into the situation in the largest leafy greens–producing state and may be used to prioritize limited national food safety resources and aid in future leafy greens–related research and foodborne incident investigations.

Lessons Learned from a Decade of Investigations of Shiga Toxin–Producing Escherichia coli Outbreaks Linked to Leafy Greens, United States and Canada

“…More STEC outbreaks were linked to romaine than to any other type of leafy green, similar to an analysis of leafy greens-related incidents linked to California (31). More iceberg was harvested and available for purchase than romaine each year during 2009-2017, although romaine harvest and availability increased over time (32,33).…”

Outbreaks of Escherichia coli O157:H7 Infections Linked to Romaine Lettuce in Canada from 2008 to 2018: An Analysis of Food Safety Context

“…Lettuce is harvested in the central coast region from April to November, in the desert region from November to March, and in the San Joaquin Valley region in spring and fall (109,123). Therefore, spring and fall coincide with transition between growing regions (124).…”

Breeding Crops for Enhanced Food Safety

“…The fresh market has resulted in a wide variety of fresh fruits and vegetables available throughout the year (Huang, 2013;Siegel et al, 2014). At the same time, the number of foodborne disease outbreaks related to consumption of contaminated fresh or minimally processed produce has been increasing (Nguyen et al, 2015;Bennett et al, 2018;Turner et al, 2019). In the United States, 48 million illnesses and 3000 deaths associated with food-borne diseases occur annually, with approximately one half associated with crops (Painter et al, 2013).…”

“…Leafy greens are annually involved in food safety incidents in the United States. From 1996 to 2016, 134 confirmed incidents, including 46 outbreaks, were identified to be linked to products from California (Turner et al, 2019) that provides one-third of the vegetables and two-thirds of the fruit and nuts in the United States according to the California Department of Agriculture (CDFA), California Agricultural Production Statistics 4 . During this period, lettuce and spinach were reported as the main vehicles of food safety incidents (39 and 26%, respectively;Turner et al, 2019).…”

“…From 1996 to 2016, 134 confirmed incidents, including 46 outbreaks, were identified to be linked to products from California (Turner et al, 2019) that provides one-third of the vegetables and two-thirds of the fruit and nuts in the United States according to the California Department of Agriculture (CDFA), California Agricultural Production Statistics 4 . During this period, lettuce and spinach were reported as the main vehicles of food safety incidents (39 and 26%, respectively;Turner et al, 2019). After three major outbreaks in 2006, the leafy green industries in Arizona and California created the Leafy Green Marketing Agreement (LGMA) with evidence-based food safety metrics that are updated to incorporate the most current state-of-the-science 5 .…”