They still haven’t found the specific source of the contamination, but U.S. officials say a deadly E. coli outbreak traced to “leafy greens” is over.

The outbreak hit Canada as well, but public health officials there declared the outbreak over on Jan. 10. They alerted the public about the outbreak on Dec. 11, reporting romaine lettuce was the cause.

A total of 67 people were infected, 42 in Canada and 25 in the United States, the U.S. Centers for Disease Control and Prevention reported Thursday. Each country reported one death.

Both the CDC and the U.S. Food and Drug Administration are continuing their testing and traceback efforts in hopes of finding out how the “leafy greens” were contaminated.

None of the agencies on either side of the border have yet named any entity in the food supply chain in relation to the outbreak. Both Canadian and U.S. law requires food producers and others in the so-called field-to-fork supply chain to maintain traceability records.

However, the regs generally only require “one step forward and one step back” efforts. That leaves officials to piece together the handoffs through the supply chain, which officials say makes traceback difficult.

Unlike Canadian officials who identified romaine lettuce as the cause of the illnesses and advised people to avoid eating it, neither the FDA nor the CDC have only referred to “leafy greens.”

The CDC’s Dec. 28 and Jan. 10 reports said the agency was “not recommending that U.S. residents avoid any particular food given the short shelf life of leafy greens and because a specific type of leafy greens has not been identified.”

Victims in both countries started becoming sick in mid-November 2017. The Public Health Agency of Canada initially reported the outbreak on Dec. 11. That same day, the U.S CDC identified a cluster of E. coli O157:H7 infections in the United States and began an investigation.

Also on Dec. 11, the FDA joined the investigation. Neither of the U.S. agencies went public with any information about the outbreak until Dec. 28. At that point, 17 people in 13 states were infected and one person in California was dead.

To view a larger version of this map, please click on the image. Source: CDC

On Jan. 10, the CDC updated its information, reporting 24 people in 15 states were involved. Neither CDC nor FDA posted any additional information until today.

“Although this outbreak appears to be over, the FDA’s outbreak investigation team is continuing to work with federal, state and local partners to determine what leafy greens made people ill, what people ate, where they bought it, and identify the distribution chain — all with the goal of identifying any common food or points where the food might have become contaminated,” the FDA reported Thursday.

Whole genome sequencing, which provides DNA fingerprints of specific pathogen strains, showed the sick people in Canada were infected with the same E. coli O157:H7 as the U.S. victims.

“Twenty-five people infected with the outbreak strain of STEC O157:H7 were reported from 15 states,” according to the CDC’s report Thursday. “Illnesses started on dates ranging from Nov. 5, 2017, to Dec. 12, 2017.

“Nine people were hospitalized, including two people who developed hemolytic uremic syndrome, a type of kidney failure. One death was reported from California.”

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