2007 Vibrio parahaemolyticus Meeting

by Michael J. Oesterling

On Friday, January 26, 2007, the Interstate Shellfish Sanitation Conference (ISSC) with assistance from the U.S. Food and Drug Administration (FDA) sponsored a meeting in Ocean City, MD, to discuss the current situation surrounding Vibrio parahaemolyticus (Vp) and raw oyster consumption. The meeting was advertised as an opportunity to learn more about the Vp situation and to provide input to the ISSC/FDA on harvesting/handling procedures.

The meeting was directed strictly to oysters and not directly at other shellfish, although they were mentioned throughout the meeting. Unfortunately, there were more bureaucrats and academics in attendance than there were industry members. I'll have more to say about this aspect later when I have a suggestion to make.

First some background information. Virginia, like all shellfish producing states, is a member state of the ISSC and must meet the requirements of the National Shellfish Sanitation Program (NSSP). The Division of Shellfish Sanitation within the Virginia Department of Health is our shellfish control agency. Within the NSSP, Vp has always been recognized as a potential illness-causing organism, but really didn't receive much attention. Most ISSC/NSSP attention had been focused on Vibrio vulnificus (Vv). This is because Vv is a life-threatening pathogen, while Vp under most circumstances is not a life-threatening pathogen.

Outbreaks of Vp have been recorded in the past. A particularly large outbreak in the Pacific Northwest and Texas during 1997 and 1998 resulted in the ISSC adopting an interim control plan addressing Vp. In 2006, there was a significant Vp outbreak in the Pacific Northwest which resulted in "hundreds" of people getting sick and causing a great deal of harm to the oyster industry.

To the FDA, this indicated that the interim control guidelines were not adequate to deal with the situation. Despite Vp not generally being a life-threatening pathogen, it still can cause food-borne illness, which raises red-flags with FDA. In 2005, the FDA submitted a proposal to ISSC addressing illnesses associated with Vp. ISSC delegates adopted a recommendation for education of licensed harvesters and shellstock dealers concerning the public health issues surrounding Vp.

In 2006, the Executive Board of ISSC directed the executive office to hold regional Vp workshops for the purpose of developing a Vp educational program. This was expanded to include discussion of potential harvest controls to reduce Vp levels in shellfish. The Ocean City meeting was the last of four regional meetings. Information was provided regarding the known basic biology for Vp. Vp is a naturally occurring marine pathogen. Unlike other Vibrio's, everyone is susceptible to Vp, not just health compromised individuals.

Fortunately, Vp normally is not life-threatening, causing varying degrees of gastroenteritis (e.g. diarrhea and stomach distress). Symptoms generally do not occur until two or three days after consumption. This makes tracing the cause of the illness somewhat difficult. Vp is a fast grower, with a minimum temperature for growth of ~50 F and growth increasing with increasing temperature. At temperatures over ~120F Vp will die.

Temperature is the single most important factor in Vp growth. If you are familiar with "ISSC-speak" this is generally referred to as "time-temperature" factors and plays into handling regulations. Perhaps the most "disturbing" portion of the meeting was the information provided by the FDA and their position and options. This was presented by Don Kramer. He emphasized that FDA views control of Vp as a significant challenge and that effective controls are not in place. This was apparent from the fact that the interim control plan, which was being followed, did not prevent the 2006 outbreak.

According to FDA data, Vp outbreaks are "predictable and preventable" and as such must be dealt with. The FDA position is that the past outbreaks only represent the "tip of the iceberg" and must be addressed. Perhaps the most distressing parts of his presentation were the data he showed regarding documented Vp cases. While there were clearly patterns for the Pacific Northwest and the Gulf of Mexico, there were no such identifiable patterns for the Atlantic Coast.

At this point a question from the audience asked specifically about Chesapeake Bay. He was unable to answer this question. A great deal of discussion occurred regarding assigning "responsibility" for an outbreak. Industry argued that they could do everything in accordance with the guidelines for maintaining temperature and proper handling, only to have their due diligence destroyed by abuses during the transport, wholesale, retail, or consumer handling.

However, if someone got sick, it would still be the harvester who would be singled out as the "cause" of the problem. This is a serious disconnect that needs to be addressed. Of all the discussions, this is probably the biggest concern for harvesters. The FDA presented their options, should the ISSC fail to enact adequate control measures for Vp. While the FDA representative went to great lengths to state that these options were not a "threat" it was very obvious that they are at the very least "a very big stick" that they will wield if they don't get their way. You decide whether that's a threat or not.

Two options were presented. The first was to enforce the action level, number of Vp present, at the retail level. This is impractical given the number of retail outlets and FDA agents available. The second option, and the most likely to be implemented, is for FDA to issue public advisories publicizing the "patterns" of Vp outbreaks and to advise the public not to consume raw shellfish during a certain period of time (summer).

Such an advisory would be extremely harmful to anyone in the shellfish business. An underlying theme regarding the potential for post-harvesting processing kept surfacing throughout the discussions. Essentially this would be a diversion from a raw, untreated product, to alleviate the Vp potential. In this same vein, the possibility of closed harvesting seasons (e.g. summer) or "for shucking only" restrictions were also mentioned.

So, what can the oyster culture/harvesting industry do? First, educate yourselves on the ISSC/NSSP, by going to their web site (www.issc.org) and reading as much as you can about Vp and Vv. More importantly, however, is to contact your ISSC representatives/members (also listed on web site) to express your concern on this issue.

In particular, I would stress how a "one size fits all" approach for the control of Vp is inappropriate given the past history of events along the Atlantic coast. The other issue of accountability must also be addressed. It is unfair that a harvester be held responsible for the "sins" of others. The ISSC must address the inequity of assigning responsibility to a harvester who has complied with all requirements and has taken due diligence to ensure the wholesomeness of his product, only to be condemned for something outside of his control.

Shellfish growers/businesses must become involved in the regulation of their industry by making sure that their concerns are known. Only by communicating with your representatives and regulatory agency can this happen. You must remember that their first concern is for human health issues. We are fortunate in Virginia to have a shellfish control agency which is very sympathetic towards industry, will listen to you and welcomes your input. My guess is that other shellfish control agencies will also welcome industry involvement.

Michael J. Oesterling
Fisheries/Aquaculture Specialist
Virginia Institute of Marine Science
P.O. Box 1346
Gloucester Point, VA 23062
(804) 684-7165
Fax (804) 684-7161