Thinking about Romaine Today

In April 2018 local, state and federal public health and agriculture agencies announced an outbreak of E. coli O157:H7 linked to romaine lettuce from the Yuma, Arizona growing area. On June 28, 2018 the Centers for Disease Control and Prevention (CDC) declared the outbreak over.

The outbreak strain was identified as PulseNet strain EXHX01.0047/EXHA26.0626. A total of 210 people in the United States infected with the outbreak strain of E. coli O157:H7 were reported from 36 states.

States reporting outbreak associated case patients

Illnesses started on dates ranging from March 13, 2018 to June 6, 2018. Ill people ranged in age from 1 to 88 years, with a median age of 28 years. Sixty-seven percent of ill people were female. Of 201 people with information available, 96 (48%) were hospitalized, including 27 people who developed hemolytic uremic syndrome (HUS), a type of kidney failure. Five deaths were reported from Arkansas, California, Minnesota (2), and New York.

WGS analysis of isolates from 184 ill people identified antibiotic resistance to chloramphenicol, streptomycin, sulfisoxazole, tetracycline, and trimethoprim-sulfamethoxazole. Standard antibiotic resistance testing of eight clinical isolates by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory confirmed these findings. Isolates from four of those ill people also contained genes for resistance to ampicillin and ceftriaxone.

In Canada there were eight illnesses of E. coli O157:H7 with a similar genetic fingerprint to illnesses reported in the U.S. investigation. The eight Canadian illnesses were reported in five provinces:  British Columbia (1), Alberta (1), Saskatchewan (2), Ontario (3), and Quebec (1). Individuals in Canada became sick between March and April 2018. One patient was hospitalized and no one died. Based on the evidence from the U.S. outbreak investigation and information provided by individuals who became sick, Canadian investigators concluded that the likely source of illness in Canada was contaminated romaine lettuce. All of the individuals reported having eaten romaine lettuce at home or in prepared salads purchased at grocery stores, restaurants and fast food chains before their illnesses occurred. Two Canadians did report traveling to the U.S. before getting sick and eating romaine lettuce while they were there.[1]

The FDA and state and local regulatory officials traced the romaine lettuce to many farms in the Yuma growing region. The FDA, along with CDC and state partners, started an environmental assessment in the Yuma growing region and collected samples of water, soil, and manure. CDC laboratory testing identified the outbreak strain of E. coli O157:H7 in water samples taken from a canal in the Yuma growing region. WGS showed that the E. coli O157:H7 found in the canal water was closely related genetically to the E. coli O157:H7 isolated in ill people. Investigators believe this finding suggests that contaminated water coming into contact with produce, either through direct irrigation or other means, is a viable explanation for transmission of the bacteria to romaine lettuce. The FDA also notes that the canal is close to a Concentrated Animal Feeding Operation (CAFO), a facility that can hold in excess of 100,000 head of cattle at any one time. FDA traceback information showed a clustering of romaine lettuce farms nearby. The Environmental Assessment report will be made publicly when complete.[2]  

And a Bit(e) of Lettuce History

[1] https://www.canada.ca/en/public-health/services/public-health-notices/2018/public-health-notice-outbreak-e-coli-infections-linked-romaine-lettuce.html

[2] https://www.cdc.gov/ecoli/2018/o157h7-04-18/0; and https://www.fda.gov/Food/RecallsOutbreaksEmergencies/Outbreaks/ucm604254.htm

Republished with permission from Bill Marler and Marler Clark. Copyright (c) Marler Clark LLP, PS. All rights reserved.