Vibrio vulnificus has been a recent news story in the past few weeks. Why? Early this spring, a 31-year-old male with a
new tattoo on his lower leg went into the Gulf of Mexico and contracted V. vulnificus through breaks in his skin from a tattoo he had gotten 5 days earlier. His tattooed skin became seriously infected and he developed cellulitis and septic shock. Despite aggressive treatment in the ICU with antibiotics and supportive care he died 2 months later. A contributing risk factor which allowed him to get so sick and die was his underlying chronic liver disease. His story was featured in several news reports and health magazines. With summer vacations planned, knowing potentially how and where you can be exposed to this bacteria and how to protect yourself can help you avoid contracting this rare but dangerous disease. Implications to the safety of having saltwater aquariums is also discussed below.
V. vulnificus is a halophilic (salt requiring) bacteria found naturally in estuaries, brackish lakes, or coastal seawater; this bacteria is capable of infecting marine fish and shellfish, specifically in oysters harvested from coastal areas. It is one of three species most common for causing human illness in the US known as vibriosis; the second most common being V. parahaemolyticus. The most common routes of infection are consuming raw or undercooked shellfish/seafood (especially oysters) or exposing a wound to infected saltwater. Nearly 90% of infections occur during the months of May through October when water temperatures are warmer. It is one reason the warmer waters of the Gulf of Mexico are a common location of infections as in the case referenced above. A second common location of infection is the Atlantic side of the state of Florida.
Over an eight-year period between 2008- 2016 there were 118 infections on the Gulf side of Florida and 91 infections on the Atlantic side. In 2014 there were 124 infections nationwide and 21 deaths; Texas had about 27 cases. In 2015 Texas had 35 cases with at least 77% being wound-related. In Florida, V. vulnificus is the most common Vibrio infection with wound infections being most common followed by oyster consumption. The Florida State Department has some of the most detailed records. In the state of Florida there were 32 cases and 7 deaths in 2014, 45 cases and 14 deaths in 2015 and 46 cases and 10 deaths in 2016. Many cases have been reported along the Gulf of Mexico in the states of Alabama, Mississippi, Louisiana, Texas and Florida. These states all test certain bodies of water at risk for being infected with Enterococci bacteria but testing for V. vulnificus is not standard. They post swim advisories to warn beach goers. Last
summer, 2016, Alabama had no beaches under a swim advisory, Mississippi had 1, Florida had 3 along the Panhandle, Louisiana had 12 and Texas had numerous beaches under advisories for high levels of Enterococci based on standards set by the environmental protection agency (EPA). If Vibrio infections continue to increase, maybe Vibrio species will be added to the testing.
V. vulnificus infections are overall very rare. In 2007 vibriosis became a reportable disease and states were encouraged to report all confirmed cases to the CDC. Yet, these infections are still largely underreported. However, we know that vibriosis causes ~80,000 illnesses every year in the US with ~52,000 being
due to eating contaminated food and ~28,000 due to wound infection. There are up to 100 deaths in the US each year. People with V. vulnificus skin infection can get seriously ill and need ICU admission for treatment and/or limb amputation.
There is a ~50% death rate from infection in patients who develop sepsis; this is considered the highest fatality rate for any bacterium. About 25% will die in a day or two after becoming ill. Any wound can become infected from a small mosquito bite, scrape or clearly open cut. In a healthy person, the skin infection or irritation is minor and may go unnoticed. Being immunocompromised due to chronic liver disease, chronic alcoholism, diabetes, chemotherapy, steroid use or medical conditions like HIV make a person at increased risk of infection. In these people, the bacteria can get into the bloodstream and cause serious or life-threatening illness. Vibrio infections progress very fast and can become evident within 4 hours after exposure. The capsule of these gram negative rods (bacilli) is thought to protect against phagocytosis. The more virulent strains of this bacteria can capture iron bound to transferrin and this is why it is so dangerous in patients with altered iron metabolism due to chronic liver disease or hemochromatosis. Increased iron serum levels enhance the growth of these bacteria and hinder appropriate actions of neutrophils, thus compounding the virulence of this organism. These patients can develop a necrotizing skin infection which leads to a blistering dermatitis. The bacteria then get into the bloodstream and an invasive septicemia can occur. This bacteria is 80x more likely to spread into the bloodstream in immunocompromised people, especially those with chronic liver disease. In chronic liver disease with cirrhosis, portal hypertension allows bacteria to directly enter the portal system, bypassing the hepatic reticuloendothelial system. These patients then get septic shock which often leads to death. In fact, these patients are 200 times more likely to die from this infection. This severe progression of disease may occur regardless of whether the initial infection was obtained from contaminated food or an open skin wound. In general, wound infections have a 25% mortality rate but in patients who develop septicemia there is a slightly greater than 50% mortality rate. Most of these patients die in the first 48 hours. Treatment includes IV antibiotic (such as ceftriaxone, doxycycline and ciprofloxacin). V. vulnificus produces extracellular toxins which destroy tissue and basement membranes in blood vessels. Large areas of necrotizing fasciitis and/or disfiguring ulcers may require surgical debridement or amputation. Studies suggest males are more likely to have serious infections as estrogen is thought to have a protective effect.
The second most common Vibrio infection in the US is Vibrio parahaemolyticus which causes on average 45,000 cases a year of which 86% are gastrointestinal and 14% are wound related; there is a 20-30% death rate for wound infections and only ~2% for gastrointestinal infections. It has a similar disease pattern to V. vulnificus but appears to be less dramatic. While this bacteria can be found anywhere, it is commonly found in Northeast Atlantic coast shellfish.
Why are we seeing an increase in the number of infections of Vibriosis? Global warming and increased water temperatures surely play a role. We are seeing an increased threat in areas of oyster harvest; some scientists believe all oysters are infected with Vibrio species in the summer months. The warm waters lead to excessive growth of the organisms. Then there is lack of freshwater dilution due to, for example, reduced flow of rivers into bays. Decreased coastal salinity levels (mostly due to climate change) also allows for greater concentrations of Vibrio within filter-feeding shellfish of the US Atlantic seaboard and Gulf of Mexico, especially oysters. Oysters are harvested from the Atlantic and Pacific coasts (~30%) but most (60-70%) are harvested from the Gulf of Mexico, particularly from Louisiana.
The FDA is considering increasing regulation of the oyster industry by requiring all oysters be treated prior to consumption to help eradicate V. vulnificus. However, in our current government regimen there is defunding of the EPA and denial of global warming and climate change. There is also anti-regulation lobbying by the oyster industry and political representation. All of these things diminish efforts to effectively reduce morbidity and mortality associated with this disease. As with other important national and global federal governmental shortsightings, individual states may have to take the lead on this issue. For instance, the state of California has had laws (since 1991) requiring consumer warning labels about the risk of consuming raw oysters from the Gulf of Mexico. Since 2003 California has banned the import of raw oysters from the Gulf of Mexico during the months of April-October unless they were previously treated.
What does this mean for aquarium and fish hobbyists? Can we get this from our tanks and fish!?! Yes, unfortunately, there is a theoretical risk. But fortunately this risk should be extremely low. You should know that V. vulnificus infects fish guts and the mucous on the skin/scales. Handling raw fish or seafood juices with open wounds/cuts/broken skin can be a route for infection. This fact would be important to know especially if you make your own fish food. Also use of natural saltwater can be a potential source of introducing infected water to your tank. There are rare reports of patients getting skin infections after scraping their hands/arms in their tank(s). Potential sources of infection in your tank include fish (which can look healthy and still be infected), shellfish (clams or crabs) or use of natural seawater. I am not aware of any risk from coral in your tank(s). Coral infected with Vibrio species (usually not V. vulnificus) in the ocean often show tissue damage (such as white spots or tissue decay). Although being immunocompromised increases your risk and potentially the severity of the illness, it is not a prerequisite. You can still get a nasty skin infection or rash. In severe cases, open cuts or damaged skin tissue comes in contact with this bacteria and the bacterial infection can lead to the breakdown of the tissue (sores and blisters) or necrotizing fasciitis and subsequently sepsis.
If you develop a skin infection after exposure to your tank or fish or after exposure to natural seawater/brackish lakes or lagoons and it progresses rapidly (a red swollen skin lesion, discoloration of the skin/bruising or blistering that rapidly gets worse and spreads into surrounding tissue), seek medical attention as soon as possible. Symptoms include pain, redness, swelling, fever and chills. Make sure you tell your healthcare provider that you own fish/fish tanks or that your skin wound was exposed to saltwater. The earlier you seek help, the better your outcome will be. In the meantime, clean the wound with soap and sterile fresh water and sterilize the wound with Betadine, hydrogen peroxide or antibacterial ointment and get to your nearest emergency room.
How can we prevent this rare but serious infection? If you have a visible skin wound or cut on your fingers, hands or arms, try to avoid contact with your fish tank all together. Avoid or use caution when participating in recreational water activities as well. If you cannot, try to cover the area with tissue glue, ointment or a waterproof bandage and wear gloves. Wash hands with soap and warm water after handling your tank. Good hygiene can insure that you continue to enjoy your hobby.
Liza Perez Jodry, MD
Secretary, Chester County Medical Society
Co-Chair Department of Pathology and Laboratory Medicine Director of Clinical Pathology
Penn Medicine Chester County Hospital
Co-owner of Coralust Reef Solutions, LLC, specializing in saltwater aquarium equipment, live coral and fish sales