Food Safety Magazine

News | December 12, 2019

Number of Illnesses in 2018 Yuma Romaine Lettuce Outbreak is Higher Than Previously Reported

By Staff

Number of Illnesses in 2018 Yuma Romaine Lettuce Outbreak is Higher Than Previously Reported

In June 2018, the U.S. Centers for Disease Control and Prevention (CDC) release a final update on the Escherichia coli O157:H7 outbreak that was tied to romaine lettuce from the Yuma, AZ, growing region. At that time, the agency officially reported a total of 210 confirmed illnesses in 36 states. There was also 5 deaths attributed to the outbreak, and 96 individuals had to be hospitalized. Twenty-seven of the victims developed hemolytic uremic syndrome, a type of kidney failure. 

Fast-forward to present-day, new documentation suggests that the outbreak caused more illnesses than what is recorded in CDC’s final outbreak update. 

In a document entitled “Shiga Toxin-Producing E. coli Infections Associated with Romaine Lettuce — United States, 2018”, the numbers are slightly different:

  • 240 case-patients from 37 states (238 of them were infected with STEC O157; 1 was co-infected with STEC O157 and STEC O61, and 2 were infected with only STEC O61).
  • 104 hospitalizations
  • 28 victims with hemolytic uremic syndrome

Here’s an excerpt from the document:

This outbreak was the largest multistate STEC O157 outbreak in several decades, eclipsing in magnitude a 2006 outbreak linked to fresh spinach [3]. As there are an estimated 26 unreported illnesses for every STEC O157 case reported to PulseNet, the true size of this outbreak was likely much larger than the 240 illnesses reported through PulseNet, suggesting that thousands of people were actually sickened in this outbreak [5]. This outbreak was also much larger than any of the 28 multistate leafy green outbreaks reported from 1998–2016, which saw a mean size of 40 casepatients [15]. It is unclear why the size of the current outbreak exceeded that of previous similar outbreaks, but the volume of contaminated product may have played a role. This is supported by the fact that the outbreak strain was identified along multiple points of a 3.5-mile stretch of an irrigation canal and that traceback led to 36 romaine fields.

The document’s corresponding author is cited as Lyndsay Bottichio from CDC. Her LinkedIn profile identifies her as an assessment epidemiologist on the agency's Outbreak Response Team. 

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