U. S. Food and Drug Administration
Center for Food Safety and Applied Nutrition
FDA Prime Connection

FDA - ISSC Vibrio Vulnificus Control Plan for Oysters
 
 
               ISSC VIBRIO VULNIFICUS CONTROL PLAN FOR OYSTERS
 
                              ANSWERS 09/21/1995
 
                                      By
 
                                  Brad Stone
                         Food and Drug Administration
                                (202) 205-4144
 
                                Sept. 21, 1995
 
 
 
On Aug. 25, the Interstate Shellfish Sanitation Conference (ISSC) -- made up
of representatives from federal and state regulatory agencies, the shellfish
industry and academia -- adopted an interim control plan designed to help
reduce the risk of Vibrio vulnificus infection from eating raw oysters.
 
The following can be used to answer questions:
 
Vibrio vulnificus is a potentially harmful marine bacterium that can be found
in oysters and transmitted to people consuming them raw or partially cooked.
Vibrio vulnificus infection is especially hazardous, even life-threatening, to
individuals with serious underlying health problems such as liver disease,
diabetes, cancer or immune disorders.  In recent years, ISSC has considered
various methods for reducing the risk of infection.
 
Vibrio vulnificus levels are known to increase as a function of ambient water
temperature, and refrigeration significantly retards their growth.  To
minimize post-harvest increases in Vibrio vulnificus levels in oysters, under
the interim control plan any state whose waters have been confirmed as the
original source of oysters associated with two or more Vibrio vulnificus
illnesses would be expected to require that the oysters be refrigerated within
a specified time after harvest.
 
The higher the temperature of the water from which the oyster was harvested,
the sooner it would have to be refrigerated.  For example, oysters taken from
an affected site during a month with an average monthly maximum water
temperature of more than 84 degrees F would have to be chilled within 6 hours
of harvesting.  Oysters taken from cooler waters could be kept unchilled
correspondingly longer.
 
FDA believes the premise that risk to consumers can be lowered through more
rapid cooling of oysters after harvest is plausible.  The times between
harvest and cooling selected for these procedures are linked to FDA research
on how rapidly Vibrio vulnificus multiplies in unrefrigerated oysters after
harvest.
 
Since much is still unknown about Vibrio vulnificus -- for example, what
levels induce illness in different individuals -- the ISSC plan also calls for
establishing a committee with representatives from FDA, the Environmental
Protection Agency, the National Marine Fisheries Service and other groups to
develop criteria to evaluate the effectiveness of the cooling standards.
 
FDA views the plan as a constructive step toward addressing the Vibrio
vulnificus problem, and will work with ISSC to have the interim plan in place
Jan. 1, 1996.  The agency will continue to work with ISSC in developing other
efficient and effective means for reducing the risk of illness from Vibrio
vulnificus and other foodborne pathogens.
 
FDA is continuing its educational campaigns on this issue.  The agency
continues to caution people with medical conditions that could put them at
risk to avoid eating raw or partially- cooked animal protein products --
including oysters.  Since some of these conditions have no symptoms,
individuals may not know they are at risk.  Consumers of raw oysters who are
uncertain whether they are at risk should check with their physicians.
 
More information on oysters and related subjects is available from the FDA
Seafood Hotline at (800) FDA-4010.
 
 
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