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Measures to control the risk of Vibrio parahaemolyticus (Vp) in live oysters

Although the Safe Food for Canadians Regulations (SFCR) came into force on January 15, 2019, certain requirements may apply in 2020 and 2021 based on food commodity, type of activity and business size. For more information, refer to the SFCR timelines.

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Introduction

The purpose of this document is to provide information on options for controlling the risk of Vibrio parahaemolyticus (Vp) in live oysters. This will help federally registered establishments and importers understand and control the risk of Vp in oysters they prepare or import for raw consumption. This document covers some generic best practices and example control measures. It is not intended as an exhaustive list of measures. Always ensure that the control(s) chosen are tailored to the uniqueness of your business and shown to be effective for your situation.

Understanding Vp

Why Vp is a hazard in live oysters

Vp can cause food-borne illness in humans.

How oysters can become contaminated with Vp

Vp is a naturally occurring bacteria found in estuaries throughout the world.

When can Vp levels increase to an unacceptable level in the harvest sites?

The level of Vp in the harvest waters can change quickly. This is due to a variety of factors such as a rise in temperature, heavy rainfall, flood or plankton blooms.

Factors affecting the growth of Vp

Controlling the risk of Vp in live oysters

Control the risk of Vp at the harvest site

Vp is a significant hazard when detected in the oysters at a harvest site and:

Measures are needed at harvest to ensure that the oysters that will be harvested meet Health Canada's guidelines for Vp in the Bacteriological guidelines for fish and fish products (end product).

The following are example measures that could contribute to acceptable levels of Vp in oysters at harvest time. You can use these alone or in combination.

When the level of Vp in the oysters is close to or exceeds Health Canada's guideline for Vp in the Bacteriological guidelines for fish and fish products (end product) you may apply measures to reduce the Vp level as long as they are validated to be effective in reducing Vp to an acceptable level. The following are examples of measures that may be considered:

Control the risk of Vp after harvest

The presence of Vp in oysters is a significant hazard when the temperature of the oysters or surrounding air after harvest and during handling, storage and transportation become favorable to its growth. Measures are needed after harvest to prevent the growth of Vp. These focus on controlling temperatures.

The following are examples of measures that could prevent Vp from increasing to an unacceptable level in the oysters after harvest. You can use them alone or in combination,

Control the risk of Vp during wet storage or relay

When Vp is present in the waters used for wet storage or relay, or present in the oysters placed there, it is a significant hazard if the conditions become favorable to its growth. To prevent the growth of Vp, use measures similar to those applied at harvest (see section 4.1).

If you use wet storage or relay to reduce the level of Vp in oysters, you must do this in accordance to the requirements outlined in section 9.4.2 of the Canadian Shellfish Sanitation Program Manual. The methods must be validated as effective in reducing Vp to an acceptable level.

Control the risk of Vp at the receiving step

The presence of Vp in oysters should have been controlled by measures taken during and after harvest. If these measures are not implemented directly by you, Vp is a significant hazard in the oysters received. Measures are then needed at the receiving step to prevent oysters with an unacceptable Vp level from being received for processing as live oysters.

The following are examples of measures you could use to prevent receiving oysters that have an unacceptable Vp level. You can use them alone or in combination.

Control the risk of Vp during processing at the establishment

Vp is a significant hazard during processing when the oysters are exposed, for a prolonged period, to a temperature favorable to its growth.

Measures are needed during processing to prevent the growth of Vp.

The following are examples of measures that could prevent Vp from increasing to an unacceptable level in oysters during processing.

Verifying your control measures

You must routinely verify that your control measures are being implemented as you intended and that they are effective. Verification activities are typically carried out by someone other than the person in charge of monitoring. You must document your verification activities.

Examples of verification activities include the following:

Depending on the risk, you may need to do different verification activities at different levels of frequency. You should increase the monitoring and verification frequency when operational conditions change (for example, change in production volume, fluctuating weather, rapidly increasing water and air temperatures), or when Vp illnesses are known to be occurring in your region. This will confirm that control measures are continuing to be practical and effective.

Changes to your control measures must be validated following one or a combination of approaches outlined in the document Evidence showing a control measure is effective.

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