Food Protection Trends - July/August 2019 - 345

and genetics of virulence (53). However, authorities must
become more proactive in implementing appropriate and
more timely controls when these super pathogens invade.
Reactive closures typically lag weeks behind peak risk, and
the magnitude of the 2013 outbreak in the NE Atlantic
could have been largely mitigated with more aggressive and
timely cooling requirements. Certainly, control authorities
also need to prevent invasions of outbreak strains by
ending the depuration/wet storage of shellfish from other
regions in flow-through systems that can release Vp or other
hazards into the local environment. This practice appears
to have resulted in a large outbreak in Galicia, Spain caused
by the Pacific Vp outbreak strain. Ballast water controls
have improved in response to mandates from selected
governments, but the maritime community needs to address
this more aggressively.
Microbial performance standards and trade
Japan and Canada have mandated performance
standards set at 100 Vp/g. The Japanese standard is for
all seafood and was implemented along with a suite of
controls, including improved cold chain actions, and
sanitary measures such as prohibiting use of harbor water
for seafood processing and reducing contamination of
fish flesh with their Vibrio-laden intestinal contents. Vp
illnesses have plummeted, but attribution to specific
controls remains uncertain (28). Canadian controls
are limited to oysters and were implemented after a Vp
outbreak in 2015 linked to oysters produced in British
Columbia (BC). BC producers have adopted measures
to sink culture gear into cooler waters, and compliance to
this standard has been good. While there have been no
Vp outbreaks since the 100/g standard was implemented,
sporadic cases occur annually. Reducing Vp levels below
100/g would be much more challenging in most U.S.
shellfish growing waters, which are much warmer than
those at the higher Canadian latitudes. Such a standard
would likely provide little public health benefit, as Vp
illnesses are much less frequently associated with Gulf
and Mid-Atlantic oysters, which have Vp levels much
higher than those of oysters from the Pacific NW and
the NE Atlantic areas. Additionally, Codex guidance on
controlling pathogenic vibrios in bivalve shellfish does not
recommend the use of microbial performance standards
(22). Legal food importation has not been implicated
in Vibrio outbreaks and is only occasionally linked to
sporadic illnesses.
Industry is the most important Vibrio risk manager
In contrast to control of other shellfish hazards, such as
pollution-associated pathogens, chemicals or toxins from
harmful algal blooms, which are managed by the control
authority with closures, control of vibrios is largely done
by industry, especially the harvesters. The aquaculture

industry is ripe for development of best management
practices programs for shellfish that are calibrated to risk
for pre- and post-harvest controls. Many growers have
branded oysters for the boutique market, and the high value
of farmed oysters merits additional safety expenditures
beyond minimum NSSP mandates. Implication in illnesses
tarnishes the brand and exposes the grower to litigation
well beyond that for wild harvesters, who tend not to
carry insurance. Farmed oysters have not yet implicated
in Vv illnesses, which often trigger lawsuits. Incoming
oyster farmers are not only more invested; they tend to
be extraordinarily well educated. The number and ratio
of oyster farmers with doctorate degrees in Alabama
where I live is greater than at FDA's Gulf Coast Seafood
Laboratory on Dauphin Island, AL, where I worked for 37
years! A more enlightened industry may signal a paradigm
shift in the role of science, which historically has not been
welcomed by the oyster industry. As science identifies
new or expanding hazards, mandates typically follow, and
these are often perceived by industry as over-precautionary.
Authorities are risk averse, and it is in their interest to
reduce risk as much as possible to insulate them from blame
in the event of illnesses or outbreaks. Mandates, along with
permitting burdens, are shrinking the operating bandwidth
of oyster production and are crushing the industry.
Industry ownership of science could expand the
operating bandwidth through better characterization of
Vibrio risk and other hazards to inform more measured
controls that track with risk. For example, mandated resubmergence times, a key element of emerging pre-harvest
controls for aquaculture practices, vary from state to state
and by gear type. States require re-submergence periods
ranging from a week to a month after a 24-30 h desiccation
step used to control biofouling in off-bottom containers.
FDA studies have been used by Alabama authorities to
reduce re-submergence times from 2 weeks to a single
week but are limited to one of several gear types and have
not been transferable to other states. These studies require
years of research using expensive and complex methods
approved by NSSP and conducted by a certified laboratory,
both of which are in short supply. The many permutations
of cultural practices, regions, oyster species and purposes
overwhelm the very slight Vibrio diagnostic capacity. These
limitations delay sanction or recognition of pre-harvest
controls, such as relocation to colder waters, which could
virtually eliminate risk. More accessible and affordable
diagnostics could empower industry to implement best
practices and to evaluate emerging technology that could
drive down risk. Dockside testing for paralytic shellfish
poison has been used by industry to manage that hazard
in shellfish in the NE Atlantic for years. If the industry
continues to recruit people who embrace science and if
technology provides user friendly/affordable diagnostics,
an era of enlightenment could improve production

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