Back to Top

Nature Notes
by Bob Thomas


What you don’t know can certainly hurt you. Knowledge is the only route to prevention against a microscopic bacterium that can cause great pain, could maim, and infrequently takes a life. Below we discuss a potentially life-threatening bacterium whose danger was only discovered in the 1970s. To date, just over 100 cases have been treated in Louisiana. The catch is that some of those infections have resulted in death; indeed, severe cases have a mortality rate of 50 percent, a statistic that should get your attention.

In this case, knowledge is not intended to keep you in a state of terror but should certainly keep you aware of the potential for harm and thus attentive to symptoms that will require quick response and immediate medical attention.

In 2000, my college buddy, Lou Groth, a geologist and avid outdoorsman, was fishing with another longtime friend, Roger St. Dizier. They were in a brackish marsh not far from their Cypremort Point camp south of New Iberia. Nothing unusual was happening, just cast-netting for bait, talking, laughing. Lou punctured his finger with the rostrum of a shrimp, something that has happened many times in his life. Unbeknownst to him, the puncture wound buried in his left ring finger an inoculation of what may be called “coastal scourge,” Vibrio vulnificus, a halophilic (salt-loving) bacterium that is common in warm hypoxic seawater and brackish marsh. There was no pain or any other sensation. He kept throwing the castnet.

Within a couple of hours, Groth noticed pain and swelling around his wedding ring. His finger continued to swell throughout the night. He went home to Lafayette the next morning and was mowing the grass at mid-morning when he realized he couldn’t slip the ring off his finger. He cut it, thus releasing a cascade of bacteria into his hand and arm. He became extremely ill and ended up in the hospital that afternoon. Again, he had no idea that a microscopic species, Vibrio vulnificus, was changing his life.

Groth was in the hospital for 18 days and required eight surgeries and skin grafts on his hand. He spent 42 hours in a hypobaric chamber, the type used for scuba-diving accidents, exposing his traumatized tissue to high-pressure oxygen to speed healing.

Ultimately he recovered, but he lost considerable portions of his left hand to amputations. He was fortunate that he was in excellent health, not immunocompromised and with no liver disorders. People with such issues are 80 times as likely to have an infection, and they have a 50 percent chance of dying when exposed to Vibrio vulnificus.

A relative of Vibrio cholerae, which causes cholera, V. vulnificus is a slightly recurved gram-negative (having structures in its wall that activate an immune response and inflammation in its host) rod-shaped bacterium. It has a flagellum, a hair-like structure whose whip-like motion propels the bacterium through its environment.

If you frequent coastal marine ecosystems for fishing, hunting, skiing, swimming, boating, or any other activity that puts you in warm, brackish water, you are in contact with these bacteria. They are and have always been abundant. But there is a difference between contact and exposure, and there is a difference between the broad term “exposure” and specific types of exposure. For example, although one can get a V. vulnificus infection by exposure through an open wound, exposure through puncture wounds is more apt to lead to an infection.

Another avenue of entry for V. vulnificus is raw seafood, especially oysters. Because Vibrio are in the water where oysters live, the bacteria are being sucked into the oysters as they siphon water (containing food particles) from their ambient habitat. Bacteria gather inside the oysters and are inside and on the surface of other seafood.

As a dedicated “oysterphile,” I wonder, “What do I do? Is there life without oysters and other seafood?”

Obviously, a person who has liver or immunity health challenges should avoid raw seafood. (See broad recommendations at the bottom of this note, but I recommend that you talk to your physician about it and not trust what works for others.)

Dr. Charles Sanders, Edgar Hull Professor and Chair of Internal Medicine at the LSU School of Medicine, says the most dangerous aspect of Vibrio infections is misdiagnosis, usually based on lack of experience with the organism and its manifestation. The most common symptoms include the following:

  • Cellulitis – a not uncommon skin infection that may be accompanied by fever and associated symptoms such as chills, fatigue, malaise, and aching muscles.
  • Diarrhea
  • Vomiting
  • Abdominal pain (myalgia)

These symptoms are often ignored by outdoors folks as just being “food poisoning,” but along the Gulf coast, they should make a warning light flash.

A more severe symptom that most people hopefully notice is “a red streak moving along an extremity,” a sure-fire indication of an infection. This is a visual expression of the bacteria’s movement through the lymphatic system. (The condition is septicemia, or more specifically bacteremia, which is commonly called “blood poisoning,” the presence of bacteria in the circulatory system).

Time from exposure to obviously threatening symptoms may be just a few hours, so it is very important for anyone who is or has recently been in coastal waters and who has a rapid onset of the above symptoms to GET TO AN EMERGENCY ROOM IMMEDIATELY. Tell the ER physician you suspect Vibrio infection and whether 1) you have been in the coastal zone and exposed to water, 2) you have recently eaten raw seafood, especially oysters, and/or 3) you have a liver disorder or are immunocompromised. Tarrying may result in amputation at best and death at worst.

To be repetitious, there are certain risk factors, such as underlying diseases, that up the ante, especially those associated with the liver. Disorders that weaken the protective operation of the liver make a person vulnerable. Cirrhosis of the liver makes Vibrio infestation very dangerous, and hemochromatosis, in which the body does not adequately metabolize iron, can weaken the capacity of the liver as iron builds up in its tissue. Add to that any form of immunocompromised disorders that make the body more vulnerable to infection.

If none of these challenges exist in the patient, then the pathogen simply moves through the liver, and cellulites is the only symptom.

The Centers for Disease Control offer the following tips on how to avoid or lessen the effects of V. vulnificus infection, especially among those who are immunocompromised or with liver malfunction (my additions in italics):

  • Do not eat raw oysters or other raw shellfish.
  • Cook shellfish (oysters, clams, mussels, crabs, shrimp) thoroughly.
  • For shellfish in the shell, either a) boil until the shells open and continue boiling for five more minutes, or b) steam until the shells open and then continue cooking for nine more minutes. Do not eat those shellfish that do not open during cooking. Boil shucked oysters at least three minutes, or fry them in oil at least ten minutes at 375°F.
  • Avoid cross-contamination of cooked seafood and other foods with raw seafood and juices from raw seafood.
  • Eat shellfish promptly after cooking, and refrigerate leftovers.
  • Avoid exposure of open wounds or broken skin to warm salt or brackish water, or to raw shellfish harvested from such waters.
  • Wear protective clothing (e.g., gloves) when handling raw shellfish.
  • Rinse your hands in diluted bleach when handling seafood; many local fishermen keep a bucket on their boat for this purpose and rinse after landing a fish or baiting a hook. Note: This is ineffective for puncture wounds.

Hey, I’m just the messenger. I doubt the boiling and “not eating” will resonate in coastal Louisiana, but you need to know that this is serious stuff and that taking the proper precautions may save your life!

Don’t let this knowledge keep you away from the coast. Just make sure you add this information to your health repertoire and share it with friends and family.


Scanning micrograph of Vibrio vulnificus,                                                  Vibrio vulnificus bacterium showing
shown at about 13,000 times actual size.                                                  its flagellum used in locomotion.
Photo by Centers for Disease Control,                                                  Photo by University of Wisconsin.
Janice Carr and James Gathany.


Hand under attack by an infestation of                                                  The aftermath: the post-infection hand
Vibrio vulnificus bacteria. Obviously,                                                     of the victim.
this type of malady is a medical emergency.                                          Photo by Dr. Russell Romero.
The cross cuts were performed to releave
pressure resulting from the swelling hand.
Photo by Dr. Russell Romero.