Vibrio Studies Slideshow

View a pdf version of a Powerpoint slideshow describing FDA-ISSC Vibrio studies that took place in the summer of 2013.

Presented by Jessica L. Jones, Ph.D, Research Microbiologist, FDA, Gulf Coast Seafood Laboratory, Dauphin Island, Alabama.




Video Presentation

View our educational video for shellfish professionals describing the biology and risk associated with Vibrio bacteria, and the steps that industry can take to minimize illness and preserve markets. This 47-minute recording of Robert Rheault's July 2010 presentation in Hyannis, MA also expands on the political and regulatory landscape and recent FDA actions.
Made possible with support from WHOI Sea Grant, RI Sea Grant, ISSC, NOAA and

Vibrio Management from Robert Rheault on Vimeo.

For more information, read our Vibrio Fact Sheet.

Read our fact sheet on Vibrio parahaemolyticus in Rhode Island farmed oysters.

View our Preparing Perfect Shellfish Consumer Brochure.

To learn about how shellfish harvesters can minimize illnesses associated with Vibrio, read our Vibrio Harvest Brochure in English and Espanol.

View our rack card with Transportation Tips for Perfect Shellfish.

View a slide presentation on Vibrio Management (in pdf format) presented at the 2010 Milford Aquaculture Seminar.

Read a summary of the Vibrio Education Workshops that were held in the summer of 2010 at various locations.

Download a sample letter in MS Word format asking your elected representatives to prevent the FDA from mandating Post Harvest Processing.

Visit the University of Georgia Marine Extension publication webpage to download copies of the Georgia Vibrio Newsletter for interstate shellfish shippers.


FDA’s Mandate to Force Gulf Oyster Sterilization

When the board of directors of the Interstate Shellfish Sanitation Conference (ISSC) met on January 10, 2011 the work of the Vibrio Management Committee consumed most of the two-day meeting. If you are not familiar with the issues surrounding Vibrio bacteria and the Food and Drug Administration’s (FDA) move to require Post Harvest Processing (PHP) of Gulf oysters for seven months a year, then I encourage you to read the background material further down on this page for the full story.

Nonetheless, here is the bare-bones “Cliff-Notes” version: Vibrio vulnificus is a naturally occurring bacteria that sickens about 90 people a year, but primarily affects those who are severely immune compromised (liver failure, diabetes, AIDS, immuno-suppressing drugs). About half of these illnesses are wound infections and half are related to eating seafood (primarily oysters).

Around half of these illnesses are fatal. (However, these numbers are now in question after a new Centers for Disease Control (CDC) report projecting significant under-reporting and lower mortality rates.) Since 2000 the FDA and industry have been working to reduce V. vulnificus deaths by 60 percent. Even though we have achieved about a 41-percent reduction, the FDA still wants to mandate PHP for Gulf oysters every April through November to bring the current average of 15 deaths a year down to less than nine.

There are four currently approved PHP processes: cool pasteurization (the patented Ameripure process), ultra high pressure (HPP), extreme freezing and low dose gamma irradiation. Gamma is approved but not currently used because of the challenges in marketing irradiated foods. Ultra-freezing is not used for summer oysters because product quality is unacceptable. East Coast states with two or more V. vulnificus illnesses would be forced to join the Gulf states in submitting to the PHP mandate.

As an industry our fear is that this is a slippery slope and the FDA really wants to mandate sterilization of all shellfish. This would open the door to cheap, sterilized shellfish from Asian nations where shellfish are grown in filth. Our only market advantage is that we can offer fresh live shellfish – once we lose that advantage our markets will evaporate.

While Vibrio problems are more prevalent in warmer waters, growers need to be aware that no state is immune from issues with these bacteria. Most states have had some illnesses associated with Vibrio bacteria and everyone in the industry should learn what steps they can take to minimize the risk of illness. The ECSGA has developed several educational brochures and has been conducting workshops in every state to educate growers, harvesters and processors.

In the recently passed Food Safety Act, Congress mandated that the FDA would have to perform a cost-benefit analysis prior to implementing a PHP mandate, so the FDA, ISSC and industry funded several studies in 2010. At the ISSC meeting we heard preliminary reports from four studies that should be complete in a few months. Keep in mind that these numbers are from preliminary reports that may be modified before publication.

1) An FDA-funded study by the Research Triangle Institute (RTI) looked at the Economic Impact and Feasibility of requiring all Gulf oysters to be Post Harvest Processed.
Researchers compared cool pasteurization, Ultra High Pressure (HPP), and low dose gamma. Their model assumes that most consumers cannot tell the difference between processed and fresh oysters. The various processes cost 3–5.8 cents per oyster (including the 20-year amortized capital cost of equipment, estimated at $75K – $3.4M). But they also found that most consumers were not as willing to buy PHP oysters, nor would they pay more. Interviews with nine restaurant owners revealed that frequent raw oyster eaters prefer fresh product, but infrequent consumers cannot tell the difference.

Most importantly, RTI found that many smaller operations wouldn’t be able to install PHP because they lack space or capital or they don’t have enough volume to justify buying even the smallest PHP device. RTI predicts 202 of 218 processing establishments would be forced to close for seven to nine months a year and over 2,000 employees would be laid off. Currently three plants process 23 percent of the Gulf landings. RTI predicts it would take two to three years and up to $35M in capital investment to develop adequate capacity to process all Gulf coast landings.

2) The University of Florida’s Dr. Steve Ottwell compared consumer preference and acceptance for processed oysters and compiled a sensory profile. At seven days post-harvest, 50-60 percent of consumers preferred traditional product, and only about 34 percent preferred processed oysters. However after 14 days post-harvest the differences in consumer preference were no longer significant.

3) Bill Huth’s group from the University of West Florida studied consumers’ willingness to pay for processed oysters. Consumers were less willing to pay for processed oysters! Using an auction simulation, panelists valued a plate of three traditional oysters at $1.44 compared with only 87 cents for three processed oysters.

4) The FDA’s Don Kramer presented agency calculations projecting the cost benefit of seven months of mandated PHP. FDA calculated that eliminating 36 percent of the illnesses and deaths related to V. vulnificus would yield an annual benefit of $124M.
We look forward to the publication of these reports in the months ahead so we can make a full examination of the methods and findings. At this point “nothing has changed” said Don Kramer. From the FDA’s viewpoint, they will look at the economic impacts and consumer acceptance, but they still view PHP and seasonal closures in the Gulf as the “most appropriate way to control illnesses from V. vulnificus.”


Vibrio Timeline

November 17, 2009 - Congresswoman Rosa L. DeLauro (D-CT) sends a letter to the Government Accountability Office requesting an independent audit of the ISSC risk management plan for Vibrio vulnificus (Vv) "to determine whether the risk management plan being used by the oyster industry, and promoted by the ISSC, is effective in reducing illnesses and death due to oysters contaminated with the Vv bacteria."

November 13, 2009 - In its news release the FDA outlines the steps it would be taking to further study banning the sale of raw oysters, including its intent to go back and work with the Interstate Shellfish Sanitation Conference (ISSC).

November 9, 2009 - Senate bill S.2752 "to ensure the sale and consumption of raw oysters and to direct the Food and Drug Administration to conduct an education campaign regarding
the risks associated with consuming raw oysters" is read twice and referred to the the Committee on Health, Education, Labor, and Pensions.

November 6, 2009 - 18 Congressional representatives sign a letter to FDA Commissioner Margaret Hamburg voicing concern over the agency's proposed post-harvest processing mandate.

November 5, 2009 - Senate bill S.2735 "to prohibit additional requirements for the control of Vibrio vulnificus applicable to the post-harvest processing of oysters" is read twice and referred
to the Committee on Health, Education, Labor, and Pensions.

November 4, 2009 - House bill HR.4022 "to prohibit additional requirements for the control of Vibrio vulnificus applicable to the post-harvest processing of oysters" is introduced and referred to the Committee on Energy and Commerce.

November 2, 2009 - ISSC responds to FDA's plan to reformulate Vv policy in a letter to Deputy Director Kraemer.

October 22, 2009 - Representatives of the East Coast Shellfish Growers Association, Pacific Coast Shellfish Growers Association, Gulf Oyster Industry Council and the Franklin County Oyster & Seafood Task Force issue a press release describing how the FDA's ban on raw oysters could devastate thousands of Gulf Coast workers and threatens other regions.

October 20, 2009 - ECSGA Executive Director Bob Rheault files his report on the reaction to the new FDA directive that "circumvents decades of cooperative negotiations between the industry, state regulators and the FDA."

October 17, 2009 - The Food and Drug Administration (FDA) drops a bombshell on attendees at the biennial meeting of the Interstate Shellfish Sanitation Conference meeting in Manchester, NH. Michael R. Taylor, Senior Advisor to the FDA Commissioner, tells attendees in his opening remarks that the FDA's job is to set national standards ensuring food safety in interstate commerce by "preventing hazards from entering the food supply."
Taylor explains that the FDA plans to mandate that "when raw oysters are harvested in waters and at times where V. vulnificus is reasonably likely to occur, the appropriate preventive measure is one of the available, validated post-harvest processing methods, or another control measure that can be validated to be equally effective."

October 17, 2009 - FDA releases a "backgrounder" explaining the rationale behind the ban.

October 16, 2009 - FDA issues a letter to ISSC members informing them of its new mandate.

April 9, 2009 - The Centers for Disease Control reports in a press release that the incidence of foodborne illness caused by Vibrio spp. over the past three years did not change significantly when compared to the previous three years (2005-2007).

June 5, 2008 - The ISSC executive board approves recommendations regarding Vibrio parahaemolyticus and Vibrio vulnificus. ISSC publishes the Vibrio parahaemolyticus Control Plan Guidance Template.

January 26, 2007 - Fisheries/Aquaculture Specialist Michael J. Oesterling of the Virginia Institute of Marine Science files his report on the Vibrio parahaemolyticus meeting sponsored by the ISSC and the FDA.

April 19, 2005 - ECSGA issues its Vibrio action letter.