October 2020

Emerging Infectious Diseases Journal

Highlights: Emerging Infectious Diseases, Vol. 26, No. 10, October 2020

Important Note: Not all articles that EID publishes represent work done at CDC or by CDC staff. In your stories, please clarify whether a study was conducted by CDC (“a CDC study”) or by another institution (“a study published by CDC in the EID journal”). Opinions expressed by authors contributing to EID do not necessarily reflect the opinions of CDC or the institutions with which the authors are affiliated. EID requests that, when possible, you include a live link to the actual journal article in your stories. Once the embargo lifts, this month’s articles will be found in the Ahead of Print section of the EID website at https://wwwnc.cdc.gov/eid/ahead-of-print.

The articles of interest summarized below will appear in the October 2020 issue of Emerging Infectious Diseases, CDC’s monthly peer-reviewed public health journal. This issue will feature Emerging Viruses. The articles are embargoed until September 16, 2020, at 12 p.m. EDT.

1.    Lessons Learned from a Decade of Investigations of Shiga Toxin–Producing Escherichia coli Outbreaks Linked to Leafy Greens, United States and Canada, Katherine E. Marshall et al.

Infections with Shiga toxin–producing Escherichia coli (STEC) bacteria cause an estimated 265,000 illnesses and cost $280 million in the United States each year. STEC infection can occur through exposure to contaminated food or water or contact with infected animals or humans. STEC infections, especially those caused by the O157 serogroup, can cause severe illness, including hemolytic uremic syndrome, a sometimes deadly and often debilitating illness affecting the kidneys. Leafy greens are the second most common source of foodborne STEC O157 outbreaks (after ground beef). Researchers examined STEC outbreaks linked to leafy greens during 2009–2018 in the United States and Canada. They found 40 outbreaks collectively resulting in 1,212 illnesses, 77 cases of hemolytic uremic syndrome, and 8 deaths. More outbreaks were linked to romaine lettuce (54%) than to any other type of leafy green. More outbreaks began in the fall (45%) and spring (28%) than in other seasons. Efforts to identify the growing and processing locations of leafy greens linked to these outbreaks through traceback investigations (a method used to find the source of the contamination in the food supply chain) were often unsuccessful. Identifying the origin of these types of outbreaks is difficult because records needed for traceback are often missing critical information and leafy greens grown on different farms are frequently mixed together. In general, STEC outbreaks can be challenging to link to a specific type of leafy green because many people eat a variety of leafy greens, eat them often, and might not remember what type they ate or when they ate them. Important knowledge gaps remain in understanding why STEC outbreaks linked to leafy greens occur, including how leafy green–associated outbreaks are affected by the season and why those outbreaks are so often linked to romaine lettuce. Federal and state health partners, researchers, the leafy green industry, and retailers should work together on interventions to improve traceability and reduce STEC contamination of leafy greens.

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Page last reviewed: October 13, 2020