The Public Health Agency of Canada said Wednesday that the new case is in Alberta and brings the total number across the country to 18.
The agency said the person became ill last month and is still recovering.
Last month, the Canadian Food Inspection Agency gave the plant in Brooks, Alta., permission to resume slaughtering cattle after being shut down for more than a month.
It is not clear when the plant will be allowed to resume shipping beef to retailers in Canada or to export products to the United States.
On Nov. 4, the agency discovered new cleanliness problems at the plant and ordered corrective action.
CFIA officials could not immediately be reached for comment.
Of the people who got sick, eight were in Alberta, six were in Quebec, three were in B.C., and one was in Newfoundland-Labrador.
The Public Health Agency says six of these 18 people were treated in hospital.
The people who became ill ranged in age from five to 63. Ten were male and eight were female.
The agency says it can take two to three weeks from the time a person becomes ill with E. coli before testing can confirm a link to the outbreak.
In severe cases E. coli bacteria can cause seizures, strokes, kidney failure and death.
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