Risk assessment of Vibrio vulnificus in raw oysters, MRA Series 8
Microbiological Risk Assessment Series, No. 8
ISBN 92 4 156310 9 (WHO)
Background (from the document)
In response to a request from Codex for scientific advice, FAO and WHO, in 2001, established a risk assessment drafting group and convened an expert consultation to take the first steps in developing a risk assessment on Vibrio spp. in seafood products that would have the most impact on public health and/or international trade. The expert consultation concluded that three species, Vibrio parahaemolyticus, Vibrio vulnificus, and choleragenic Vibrio cholerae were the species responsible for most cases of human illness caused by vibrios, and several seafood vehicles associated with these illnesses were identified. Work was thus undertaken on the following pathogen-product combinations:
- V. parahaemolyticus in raw oysters harvested and consumed in Japan, New Zealand, Australia, Canada and the United States of America.
- V. parahaemolyticus in finfish consumed raw.
- V. parahaemolyticus in bloody clams harvested and consumed in Thailand.
- V. vulnificus in raw oysters harvested and consumed in the United States of America.
- Choleragenic V. cholerae O1 and O139 in warm-water shrimp in international trade.
These five individual risk assessments illustrate how different approaches were used to reflect the national capacity to generate data, including health statistics and data on the pathogen and the commodity of concern. The assessments considered information on Vibrio spp. in seafood that was generated and available at regional and national levels and this information formed the substantive basis from which the risk assessments were developed.
The current document describes the risk assessment of V. vulnificus in raw oysters. When this work began, a draft risk assessment model had been developed in the United States of America to assess the public health risk associated with V. parahaemolyticus in raw oysters. The above-mentioned FAO/WHO V. parahaemolyticus risk assessment in raw oysters looked at how to adapt the model developed in the USA to the situation in other countries. The purpose of this risk assessment was to investigate further the utility of the United States draft V. parahaemolyticus model, which was published in 2001 , together with the additional work undertaken by FAO and WHO on the risk assessment of V. parahaemolyticus, and determine if it could be adapted to a different pathogen, V. vulnificus. The current risk assessment was developed in the same raw oyster vehicle and also, for reasons of data availability, for the same geographic region, thereby representing a very similar exposure scenario. This risk assessment was also undertaken because V. vulnificus illness has one of the highest mortality rates of any foodborne disease and has emerged as a food safety issue in a number of countries and regions including Europe, Japan, New Zealand, Republic of Korea and the USA.