Food Protection Trends - May/June 2023 - 233

consumed without further cooking. Transmission pathways
of Salmonella to humans originating from live poultry also
represents a concern, including through backyard flocks (23),
" pet " baby chicks (2), and contamination of water, land, and
other raw agricultural commodities (e.g., the contamination
of raw produce by chicken pellets used as fertilizer; (15)).
Consequently, improved control of Salmonella in poultry has
a substantial potential for reducing the public health burden
of this foodborne pathogen.
Reduction of human salmonellosis cases linked to raw
poultry is challenging, as supported by FoodNet reporting
in 2017 that salmonellosis incidence in the United States
reached 16.0 cases per 100,000 people, a number that failed
to meet the Healthy People 2020 goal of reducing human
salmonellosis to 11.4 cases per 100,000 people (37). Changes
in detection methodologies, particularly the use of more
rapid culture independent diagnostic tests (CIDTs), may
account for some reported cases that otherwise would have
gone undetected. The number of culture-confirmed cases in
2017 was just 14.6 cases per 100,000 people, with the rest
(1.4 cases per 100,000 people) detected through CIDTs (6).
Even assuming, however, that all cases detected by CIDTs
would have gone unreported but for the availability of
CIDTs, salmonellosis incidence still far exceeds the Healthy
People 2020 goals. Remarking on the persistently high levels
of salmonellosis incidence, Centers for Disease Control and
Prevention researchers have stated that " the identification of
infections that might not have been detected before adoption
of CIDTs cannot explain this overall lack of progress " (32).
The challenges associated with controlling human
salmonellosis cases due to raw poultry are multifaceted and
include, but are not limited to (i) the need to use a systems
approach (from poultry breeders to slaughter and processing
and onto restaurants and home cooks); and (ii) the fact
that Salmonella enterica, the species responsible for human
salmonellosis, is extremely diverse and includes subtypes that
are very unlikely to cause human disease but are frequently
isolated from certain animals (e.g., Salmonella enterica subsp.
enterica serovar Kentucky sequence type 152), as well as
other subtypes that are substantially more likely to cause
human disease (e.g., multidrug-resistant Salmonella Infantis
(16, 33)).
Rational identification and prioritization of risk management
strategies are paramount to improved control of human
salmonellosis cases linked to raw poultry. A key strategy to
achieve this will be to construct appropriate risk models and
perform risk assessments that can transparently evaluate the
public health impact of different intervention strategies. Importantly,
these risk assessments will need to account for the
complexity of the challenge (e.g., they will need to explicitly
and quantitatively account for virulence differences among
Salmonella subtypes) and will need to be designed and used
to assess the impact of a wide range of risk management practices.
Following these principles will encourage use of these
risk assessments by different stakeholders to address risk
management questions within their purview (e.g., what is the
impact of different regulatory policies [for regulatory agencies]
and what is the impact of different specific interventions
[for industry]). This article aims to outline, on the basis of
discussions with a wide range of collaborators participating
in the Coalition for Poultry Safety Reform, key categories
and types of different risk management questions that risk
assessments of Salmonella in raw poultry should assess (7).
The Coalition for Poultry Safety Reform represents different
stakeholders, including consumers, industry, regulators, and
scientists. In addition, we also outline key data and model
needs that should be addressed to allow for these types of
risk assessments. This information will hopefully not only
facilitate development of risk assessments that can be used
to inform identification of Salmonella control strategies to
positively impact public health but also encourage more
foundational research that will fill some of the data gaps that
need to be addressed to further improve risk assessments. Finally,
although this article addresses a number of key factors
and variables that should be considered in risk assessments
addressing Salmonella transmission in poultry, it is important
to acknowledge that the complexity of the issue at hand is
substantial and that Salmonella transmission in poultry may
be impacted by many variables that are not mentioned here
(e.g., weather, bird breeds) and that could also be considered
in future specific risk assessments.
Poultry preharvest risk management options
Preharvest poultry production includes a number of
distinct stages that could be targeted by interventions that
may reduce the number of human salmonellosis cases due
to raw poultry. Key stages of poultry production include (i)
primary breeders; (ii) pullet production; (iii) breeders (egg
production for broilers); (iv) hatchery; (v) broiler production
for slaughter or processing; (vi) live haul; and (vii) feed
milling. Key risk management strategies at the live animal
stage may focus on reducing overall Salmonella prevalence
or prevalence of specific Salmonella serovars of public health
relevance and/or reducing the number of animals or flocks
that carry high levels of Salmonella or Salmonella serovars
of public health relevance. Specific preharvest interventions
that have been used or tested include (i) strict biosecurity
measures, including poultry house practices that reduce Salmonella
contamination (e.g., regular cleaning and sanitation
of poultry houses, water acidification, litter management,
and use of pelleted feeds); (ii) use of autogenous vaccines for
breeders and pullets (focusing on serovars of concern, which
are often the most commonly found serovars); (iii) use of live
attenuated vaccines for broilers; and (iv) use of competitive
exclusion cultures to prevent colonization of chicks with Salmonella.
An overview of preharvest interventions is provided
by the U.S. Department of Agriculture (USDA) in " FSIS
Guideline for Controlling Salmonella in Raw Poultry " (35).
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