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By 13 July 2018, 10 of 11 cases had been re-interviewed.
All 10 cases (100%) reported chicken consumption, and 7
cases (70%) reported following a kosher diet. Cases reported
yes (60%) or maybe (30%) to exposure to kosher or halalprocessed chicken. In addition, 6 cases (60%) could recall
chicken brand information, with 5 cases (50%) reporting
exposure to Brand X kosher poultry during the week before
illness onset. Brand X kosher poultry was produced at one
of the kosher processing facilities where FSIS isolates were
collected that were closely related to clinical isolates by WGS.
Active laboratory surveillance for cases throughout July
and August 2018 identified six additional WGS-related
clinical isolates for epidemiologic follow-up. Of the cases
able to be contacted for re-interview (n = 14), 100%
reported chicken exposure. In the interview, 11 of 14 cases
were questioned about kosher chicken exposure specifically,
of which 9 cases (82%) reported yes to exposure. Of these
cases, 7 individuals reported exposure to Brand X kosher
poultry (78%). Because of the genetic relatedness (0 to 8
SNPs) between isolates of clinical cases reporting exposure
to Brand X kosher poultry and the FSIS chicken isolates
from the facility that produced Brand X, FSIS proactively
contacted the company that produced Brand X in early
August 2018 to make it aware of the ongoing investigation
(10). In late August, CDC and FSIS publicly reported
the link between illnesses in the outbreak and Brand X
kosher poultry products and provided consumer messaging
reiterating safe handling and cooking practices for raw
chicken products (1, 12).
At investigation closeout in December 2018, the outbreak
consisted of 25 cases from six states (Massachusetts, 2;
Maryland, 1; New York, 16; Ohio, 1; Pennsylvania, 4; and
Virginia, 1) (3). Estimated illness onset dates ranged from
September 2017 to August 2018. The median age of cases
was 16 years (range <1 to 75 years); 50% were female.
Of 22 cases, 11 (50%) were hospitalized, and one death
was reported. The severity of this illness was higher than
expected, as the typical hospitalization rate among people
with Salmonella infection is approximately 22% (6). All
interviewed cases (n = 20) reported chicken consumption
during the week before illness onset. Of those recalling brand
information, 83% (10 of 12) of cases reported exposure to
Brand X kosher poultry.
DISCUSSION
This multistate cluster was initially detected by the
NYSDOH in June 2018 as a subset of cases within an
endemic Salmonella serotype I 4,[5],12:i:- PFGE-based
cluster in NYS (pattern JPXX01.0621) highly related by
WGS within 0 to 8 SNPs. PFGE analysis was not able to
distinguish this subcluster of genetically related cases. Pattern
JPXX01.0621 is a common strain of Salmonella I 4,[5],12:i:and is the most common pattern of the serotype reported
to PulseNet, the national subtyping network of public

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Food Protection Trends March/April

health and food regulatory agency laboratories coordinated
by CDC. Based on PulseNet data from 2013 to 2018, an
average of 233 isolates (range 175 to 341) of Salmonella
serotype I 4,[5],12:i:- with PFGE pattern JPXX01.0621
were uploaded to the PulseNet database annually, with this
pattern accounting for approximately 10% of all Salmonella I
4,[5],12:i:- isolates (7). Unlike the PFGE-based case cohort,
the cases whose isolates were highly related by WGS shared
a tendency to consume kosher food products. A subsequent
query using the NCBI Pathogen Detection browser identified
additional WGS-related clinical isolates, clustered both
temporally and spatially within NYS and from neighboring
states (13). The epidemiologic information gathered on these
cases supported the link between illness and exposure to a
kosher food product. Concurrently, USDA chicken isolates
related by WGS to the clinical isolates within 0 to 6 SNPs
were identified in the NCBI Pathogen Detection browser.
State and federal health partners collaborated to evaluate
the evidence and determine that illnesses were associated
with consumption of Brand X poultry. Epidemiologic
investigations by separate state public health departments
indicated kosher chicken exposure as a commonality among
cases, specifically Brand X.
Because of compelling epidemiologic, environmental,
and laboratory findings, the coordinated response by
federal health officials was swift. Based on the available
epidemiologic and laboratory information linking illnesses
to Brand X kosher raw poultry, on 24 August 2018, FSIS
issued a public health alert notifying consumers that Brand
X kosher raw poultry in commerce may be contaminated
with Salmonella linked to human illnesses (12). Although
there was not sufficient information on the type of
chicken products to recommend a recall, the alert notified
consumers about the potential health risks associated
with the product. On 29 August 2018, CDC posted an
investigation notice to inform the public about reports
of human illness linked to Brand X kosher raw poultry
exposure (1). The notice did not advise consumers to avoid
eating Brand X kosher poultry but reinforced practices on
how to properly handle and cook raw chicken.
Although exposure to raw poultry is not a novel source
of salmonellosis in humans, using WGS as a tool to detect
the source of this outbreak was novel (5). Because of
the endemic nature of the PFGE pattern involved in this
cluster linked to a common exposure, PFGE analysis alone
was insufficient to identify the epidemiologically linked
subcluster of cases or guide public heath action to prevent
additional cases. Integral to the success of this investigation
was the use of WGS to differentiate the isolates in a cluster
by genetic relatedness, in combination with the capability
of the NCBI Pathogen Detection browser to identify related
clinical and food isolates not identified locally. Epidemiology,
laboratory, and environmental health partners at the local,
state, and federal levels worked in unison to ultimately detect

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