September 13, 2019

CDC, several states, the U.S. Food and Drug Administration (FDA), and the Canadian Food Inspection Agency investigated a multistate outbreak of E. Coli O103 and E. Coli O121 infections linked to ground bison from Northfork Bison Distributions, Inc.

Public health investigators used the PulseNet system to identify illnesses that may have been part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA fingerprinting is performed on E. coli bacteria isolated from ill people by using a standardized laboratory and data analysis method called whole genome sequencing (WGS). CDC PulseNet manages a national database of these sequences that are used to identify possible outbreaks. WGS gives investigators detailed information about the bacteria causing illness. In this investigation, WGS showed that bacteria isolated from ill people were closely related genetically. This means that people in this outbreak were more likely to share a common source of infection.

A total of 33 people infected with the outbreak strain of STEC O103 (8 people), STEC O121 (21 people), or both (4 people) were reported from 8 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Illnesses started on dates ranging from March 18, 2019, to August 11, 2019. Ill people ranged in age from 6 to 80 years, with a median age of 27. Fifty-two percent of ill people were female. Of 31 ill people with information available, 18 hospitalizations were reported. No deaths were reported, and no cases of hemolytic uremic syndrome, a type of kidney failure, have been reported.

WGS analysis of isolates from 26 ill people was performed; isolates from 10 ill people predicted antibiotic resistance to streptomycin, sulfisoxazole, tetracycline, and trimethoprim-sulfamethoxazole, and 16 isolates from ill people did not show evidence of antibiotic resistance. Standard antibiotic susceptibility testing by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory is currently underway. These findings do not affect treatment guidance since antibiotics are not recommended for patients with STEC O121 or STEC O103 infections.

Investigation of the Outbreak

This investigation began on June 10, 2019, when PulseNet notified CDC of this outbreak. Epidemiologic, traceback, and laboratory evidence indicated that ground bison produced by Northfork Bison Distributions, Inc., was the likely source of this outbreak.

In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. Of the 23 people who were asked, 13 (57%) reported that they ate or maybe ate ground bison. Ill people ate ground bison in burgers from several different restaurants or prepared ground bison at home.

Federal, state, and local officials collected records from the restaurants where ill people ate ground bison. These records showed that the ground bison produced by Northfork Bison Distributions, Inc., was sold in several restaurants where ill people ate ground bison. The outbreak strain of STEC O121 was isolated from bison burgers manufactured by the Canadian firm.

On July 16, 2019, Northfork Bison Distributions, Inc., in Saint-Leonard, Quebec, Canada, recalled ground bison and bison patties (referred to as Bison Burgers and/or Buffalo Burgers) produced between February 22, 2019, and April 30, 2019. Consumers should not eat, and restaurants and retailers should not serve or sell, recalled ground bison products.

As of September 13, 2019, this outbreak appears to be over.