6
I. Karunasagar
Considering these findings of the FAO/WHO risk assessment for
V. parahaemolyticus, CCFH decided to develop the Code of Hygienic Practice
for control of pathogenic Vibrio spp. in seafoods, which has now been adopted
(CAC/GL-73, 2010). During the process of drafting this Code, it was brought to the
attention of the Codex member countries that United States has developed a risk
reduction tool that can be used to estimate risk when environmental conditions like
environmental temperature varies. While finalizing the Code, the 41st session of
the CCFH recognized the need to provide countries with tools to assist them in the
implementation of the guidelines under the various conditions that exist in different
regions and countries. Such tools are envisioned to support countries in their efforts
to use risk-based approaches in the selection of control measures appropriate for
their seafood species, primary production and post-harvest practices. As the tool
developed by the United States of America is based on the conditions and data of
the USA, its broader application could not be recommended without a review of its
validity when applied to non-USA scenarios. In light of this, the CCFH requested
FAO/WHO to convene an Expert Meeting with the following terms of reference:
• Conduct validation of the predictive risk models developed by the United States
of America based on FAO/WHO risk assessments, with a view to constructing
more applicable models for wide use among member countries, including
adjustments for strain virulence variations and ecological factors;
• Review the available information on testing methodology and recommend microbiological methods for Vibrio spp. in order to monitor the levels of pathogenic
Vibrio spp. in seafood and/or water; and
• Conduct validation of growth rates and doubling times for V. parahaemolyticus
and V. vulnificus in Crassostrea virginica (eastern or American oyster) using
strains isolated from different parts of the world and different bivalve molluscan
species.
FAO/WHO conducted this Expert meeting during September 13–17, 2011 at
Rome. The Expert meeting evaluated the US risk calculator with a view of
determining the context to which it is applicable and the potential modifications
that may be needed for application, in other geographical regions. The Meeting
concluded that Vibrio parahaemolyticus calculator tool may be used to estimate
relative risk reductions, primarily because of the linear dose–response, associated
with temperature controls (post-harvest refrigeration) in areas in which the strain
virulence, initial concentration and growth rates of V. parahaemolyticus in the
bivalve spp. of concern are similar to that indicated in data from the United
States. It was noted that besides temperature, there may be other ecological factors
affecting the levels of V. parahaemolyticus in oysters. For example, the study
done in India (Deepanjali et al. 2005) shows that in a tropical environment, where
temperatures are favourable for V. parahaemolyticus, variations in levels occur and
that this may be influenced by other ecological factors. The report of Eyles et al.
(1985) that V. parahaemolyticus does not multiply in Sydney rock oysters even
at 30
ı C suggests that the tool based on multiplication of V. parahaemolyticus in
American oysters (Crassostrea virginica) cannot be directly applied to other bivalve
I. Karunasagar
Considering these findings of the FAO/WHO risk assessment for
V. parahaemolyticus, CCFH decided to develop the Code of Hygienic Practice
for control of pathogenic Vibrio spp. in seafoods, which has now been adopted
(CAC/GL-73, 2010). During the process of drafting this Code, it was brought to the
attention of the Codex member countries that United States has developed a risk
reduction tool that can be used to estimate risk when environmental conditions like
environmental temperature varies. While finalizing the Code, the 41st session of
the CCFH recognized the need to provide countries with tools to assist them in the
implementation of the guidelines under the various conditions that exist in different
regions and countries. Such tools are envisioned to support countries in their efforts
to use risk-based approaches in the selection of control measures appropriate for
their seafood species, primary production and post-harvest practices. As the tool
developed by the United States of America is based on the conditions and data of
the USA, its broader application could not be recommended without a review of its
validity when applied to non-USA scenarios. In light of this, the CCFH requested
FAO/WHO to convene an Expert Meeting with the following terms of reference:
• Conduct validation of the predictive risk models developed by the United States
of America based on FAO/WHO risk assessments, with a view to constructing
more applicable models for wide use among member countries, including
adjustments for strain virulence variations and ecological factors;
• Review the available information on testing methodology and recommend microbiological methods for Vibrio spp. in order to monitor the levels of pathogenic
Vibrio spp. in seafood and/or water; and
• Conduct validation of growth rates and doubling times for V. parahaemolyticus
and V. vulnificus in Crassostrea virginica (eastern or American oyster) using
strains isolated from different parts of the world and different bivalve molluscan
species.
FAO/WHO conducted this Expert meeting during September 13–17, 2011 at
Rome. The Expert meeting evaluated the US risk calculator with a view of
determining the context to which it is applicable and the potential modifications
that may be needed for application, in other geographical regions. The Meeting
concluded that Vibrio parahaemolyticus calculator tool may be used to estimate
relative risk reductions, primarily because of the linear dose–response, associated
with temperature controls (post-harvest refrigeration) in areas in which the strain
virulence, initial concentration and growth rates of V. parahaemolyticus in the
bivalve spp. of concern are similar to that indicated in data from the United
States. It was noted that besides temperature, there may be other ecological factors
affecting the levels of V. parahaemolyticus in oysters. For example, the study
done in India (Deepanjali et al. 2005) shows that in a tropical environment, where
temperatures are favourable for V. parahaemolyticus, variations in levels occur and
that this may be influenced by other ecological factors. The report of Eyles et al.
(1985) that V. parahaemolyticus does not multiply in Sydney rock oysters even
at 30
ı C suggests that the tool based on multiplication of V. parahaemolyticus in
American oysters (Crassostrea virginica) cannot be directly applied to other bivalve