By Bryan Fleuch
UF/IFAS Collier County Extension Director
Florida Sea Grant Extension Agent
Questions have been floating around as to whether it is safe to swim in local waters because of a recent incident where an elderly woman had to have her leg amputated due to exposure to Vibrio vulnificus. So far, nine people have died in Florida since January from the baceria. In case you are not familiar with Vibrio, here are some frequently asked questions about it, that can help you in case you are concerned.
What is Vibrio vulnificus?
Vibrio vulnificus is a bacterium that occurs naturally in warm brackish and saltwater environments in the Gulf of Mexico. The presence of Vibrio in our waters is NOT an indication of pollution During the warmer months, this bacterium can reach particularly high concentrations in filter-feeding shellfish (i.e. oysters, clams) that inhabit coastal waters. Foodborne illness from V. vulnificus is almost exclusively associated with consumption of raw oysters. Properly cooking the shellfish can totally eliminate the risk. Although most cases are likely underreported and unrecognized, infection from V. vulnificus is still quite rare. Data from the Food and Drug Administration (FDA) indicated the average occurrence of V. vulnificus infection was less than 30 cases per year between 2002 and 2007, and these were due to consumption of raw oysters
What activities can cause illness related to Vibrio vulnificus?
Eating raw oysters or lightly cooked seafood, or exposing an open wound to seawater harboring V. vulnificus can result in infections (50% of U.S. cases are from infections due to open wounds). Wound infection can occur when a previously obtained wound, sore, scratch, or burn is exposed to seawater or when a wound is obtained while fishing, such as a puncture from a hook or fish teeth, cuts or scratches from shells or finfish, or cuts and scrapes from crab traps or other fishing gear. The bacterium is often isolated from oysters and other shellfish as well as from their habitats during the summer months in warm, coastal waters. There is no evidence, however, of person-to-person transmission.
Who is at risk and why?
People with previous medical conditions can acquire V. vulnificus disease from eating raw seafood, especially oysters. Those persons with either immune system disorders (such as AIDS) or on immunosuppressive medication, chronic liver disease, hemochromatosis (iron overload disease), and/or insulin-dependent diabetes are at the greatest risk for infection and should avoid raw seafood products. Even though foodborne illness associated with V. vulnificus is rare, fatality rates of immunosuppressed patients infected by V. vulnificus can approach 60 percent. Persons with these pre-existing medical conditions, or persons who are very young or elderly, should also avoid exposure to seawater/brackish water.
What are the diagnostic signs and symptoms associated with Vibrio vulnificus?
Wound infection symptoms may develop within 3 to 24 hours and include:
• Rapid swelling, pain, and reddening of skin around wound (present in 100% of infections)
• Large blisters, die-off of tissue around wound (30 – 50% of infections)
• Gangrene (<10%)
• Consumption of raw or undercooked seafood may occur in 12 to 48 hours and include:
• Nausea/stomach pain/vomiting
If Vibrio vulnificus infections are left untreated in people at risk for serious infection, symptoms may quickly increase in severity and include:
• Fluid accumulation, especially in legs
• Blood-filled large blisters, mainly on extremities
• Septicemia (bacteria enter and spread through blood stream)
• Shock (rapid drop in blood pressure)
Amputation of appendages and/or surgical removal of dead tissue may be required to prevent death.
Protect wounds from direct contact with seawater (use water-proof bandages, gloves, shoes, and clothing) and avoid punctures, scrapes, or cuts while fishing, harvesting, or handling raw seafood.