Two outbreaks of Shiga toxin-producing E. coli O26 (STEC O26) infections are being looked at by US agencies.
As of December 18, 53 people infected with STEC O26 have been reported from nine states and 20 people have been hospitalized.
Reports to PulseNet of new illnesses have slowed substantially since the peak in October.
Chipotle Mexican Grill closed 43 restaurants in Washington and Oregon in November but all these sites have reopened.
The US Centers for Disease Control and Prevention (CDC) said epidemiologic evidence suggests a common meal item or ingredient served at Chipotle Mexican Grill restaurants as a likely source but no food has been identified.
The agency is also investigating another outbreak of a different rare DNA fingerprint of Shiga toxin-producing E. coli O26 (STEC O26) linked to Chipotle Mexican Grill.
It said it is not known if these infections are related to the larger outbreak of STEC O26 infections.
A total of five people in Kansas (1), North Dakota (1), and Oklahoma (3) ate at a Chipotle Mexican Grill in the week before illness started.
Illness dates range from November 18 to November 26.
Salmonella from poultry
The Public Health Agency of Canada (PHAC) is monitoring an outbreak of Salmonella infections which has affected 98 people.
Salmonella Infantis has been reported in nine provinces: British Columbia (7), Alberta (12), Saskatchewan (2), Manitoba (2), Ontario (57), Quebec (14) Nova Scotia (2), Prince Edward Island (1) and New Brunswick (1).
Information from those who became sick indicates that improper handling and repackaging raw poultry products could be the source. Others reported eating various brands and types of chicken.
A sample of raw chicken taken from the home of a sick individual tested positive for the same strain of Salmonella Infantis which suggests raw chicken is the source of the outbreak, said the agency.
Individuals became sick between March 15 and December 12 with the majority of cases (60%) being female, with an average age of 40 years.
Sixteen people have been hospitalized and all have recovered or are recovering.
E. coli in salad
However, the CDC said the Shiga toxin-producing E. coli O157:H7 outbreak linked to Rotisserie Chicken Salad from Costco was over.
The FDA, Costco and its suppliers, including Taylor Farms Pacific, analyzed the supply chain of the rotisserie chicken salad.
The evidence did not identify a single ingredient as the cause of the outbreak.
The Montana Public Health Laboratory tested a sample of celery and onion diced blend by Taylor Farms Pacific from a Costco store in Montana. Preliminary results indicated E. coli O157:H7.
This was used to make the Costco rotisserie chicken salad eaten by ill people.
However, further laboratory analysis by the FDA was unable to confirm E. coli O157:H7 in the sample.
Fourteen of 16 people purchased or ate rotisserie chicken salad from Costco in the week before illness. CDC said the most recent illness started on November 3.
Nineteen people were infected from seven states, five were hospitalized and two developed hemolytic uremic syndrome, a type of kidney failure.