The US Centers for Disease Control and Prevention (CDC) said five rare DNA fingerprints of Listeria are part of the investigation after whole genome sequencing (WGS) showed they are closely related genetically.
Twenty-four ill people have been reported from nine states since August 8, 2010 and 21 were hospitalized. Five illnesses were pregnancy-related; one resulted in a fetal loss and one person from Ohio has died, said the agency.
Link to soft cheese
The investigation has not conclusively identified the source, but most ill people interviewed reported eating soft cheese before becoming ill.
“Eighteen (82%) of the 22 ill people with available information reported eating soft cheeses in the month before becoming ill,” said CDC.
“Four (57%) of seven ill people who specified a brand of cheese reported brands distributed by Karoun Dairies. No other brand of cheese was reported more than once.”
Karoun Dairies has recalled and stopped distributing certain cheeses due to possible contamination.
None of its products have tested positive for Listeria.
Products were distributed to retail outlets, including food service outlets and supermarkets throughout the country.
They are vacuum packed, in jars or in pails, and have weights varying from 5 ounces to 30 pounds.
The cluster was identified in August 2015 after investigators saw an increase in one of the five rare PFGE fingerprints reported to PulseNet (the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC).
WGS found four other PFGE fingerprints were closely related genetically to the first one.
Illnesses associated with those PFGE fingerprints were added to the investigation, including illnesses more than five years ago.
The number of ill people is: California (14), Colorado (1), Illinois (1), Massachusetts (2), Michigan (1), New York (2), Ohio (1), Tennessee (1), and Washington (1).
Canada and other outbreak updates
The Canadian Food Inspection Agency (CFIA) said it is also investigating but there have been no illnesses reported.
Safeway is recalling Flight of Cheese trays prepared in store which may contain recalled Yanni and Gopi brand cheese due to possible Listeria monocytogenes contamination.
Distribution includes Alberta, British Columbia, Manitoba, Ontario and Saskatchewan.
Tree of Life Canada earlier recalled Yanni and Gopi brand cheese products distributed nationally due to possible contamination.
Meanwhile, in the ongoing outbreak of Salmonella the FDA has issued an Import Alert to include cucumbers from Rancho Don Juanito de R.L. de C.V. in Baja, Mexico.
This was based on identification of Salmonella through import sampling of products.
Traceback investigations determined the firm was the primary source of cucumbers shipped to Andrew & Williamson.
Another outbreak appears to be over after CDC reported last week that the numbers of reported cases of cyclosporiasis have returned to baseline levels.
As of September 14, 546 ill people with confirmed cyclosporiasis had been reported from 31 states.
Clusters of illnesses were identified in Texas, Wisconsin, and Georgia. Cilantro from Puebla, Mexico was supplied to restaurants at which people identified in illness clusters ate indicating it was responsible for some illnesses.