Vibrio bacteria — A Potentially Deadly but Preventable Threat to Anglers and Beachgoers

Vibrio is a naturally occurring halophilic (“salt liking”) bacteria that is found in all of our bays as well as coastal waters here in Texas. If you’ve been in saltwater, you’ve encountered Vibrio. Depending on the location and time of year, a single drop of seawater can contain 100 or more Vibrio cells. Vibrio encompasses a number of different species, but when most people hear “Vibrio”, they think about the rare but traumatic flesh and limb destruction that it can cause, colloquially referring to it as “flesh eating bacteria”. If you are an angler or commercial harvester, you may know someone who has been affected by a Vibrio infection. All told, there are approximately 12 species of Vibrio that can cause illness in humans through either consumption of contaminated seafood or infection of open wounds. This article focuses on Vibrio vulnificus, a species that causes wound infections – when and where the risk is most pronounced, how you can reduce risk, and what to do if you suspect that you have been exposed. It is our hope that the information here will be useful to anglers, seafood processors, commercial harvesters and beachgoers who venture out into our local marine waters.

How can you be exposed to Vibrio?

Infection starts when Vibrio enters the body through open wounds that range from cuts on the body to something as small as a piercing, mosquito bite, or puncture from a fishhook or fin. The risk is very low if you do not have an obvious open wound but increases if you do. Healthy individuals can become infected, but risk is usually much higher in those individuals with compromised immune systems that have chronic liver disease, diabetes, or elevated iron levels. The most common activities by which people become infected are swimming, fishing, or handling raw seafood.

Despite the rareness of Vibrio infections, the consequences are potentially severe and life threatening. For example, symptoms of skin infection can begin to develop within 4 hours of exposure and then spread rapidly. If not treated properly, loss of limbs and/or death can occur as quickly as 24-48 hours after exposure. In fact, about 1 in 5 persons who are infected with Vibrio will die from the infection.

Understanding the risk of Vibrio infection

Vibrio is present year-round in marine environments, although it’s population will fluctuate considerably with water temperature. Highest abundances (and highest risk to human health) typically occur when water temperatures exceed ~70°F. This generally occurs from March to November in Texas bays and coastal waters. In addition, recent work here at the Harte Research Institute, funded by Texas Sea Grant, has shown that Vibrio populations temporarily explode when there is an influx of Saharan dust (Figure 2), which usually happens between May and August. This may be due to the high levels of iron that get deposited in surface waters when dust falls out of the sky – Vibrio is greedy for iron and responds rapidly to sudden additions of growth-inducing elements like iron.

How can you reduce your risk of infection?

1. If you have any kind of open wound or rash, consider avoiding saltwater or brackish water, as any skin puncture (small or large) can allow Vibrio to enter the body.
2. Wear protective clothing such as puncture resistant gloves when handling shellfish or fish and wear close-toed shoes when walking around in the water.
3. If you get even a tiny cut or abrasion while swimming or wading, such as a cut from an oyster shell or a puncture from a fishing hook or fish fin, treat the wound immediately! Do not wait! Wash the wound with antibacterial soap and large amounts of warm fresh water. Look for a soap labelled 'antibacterial’. Chlorhexidine-based products such as Hibiclens® scrub, which can be purchased at your local pharmacy, provide lasting antibacterial effect. Then apply a topical antibacterial such as Triple Antibiotic Ointment or Bacitracin. Cover the wound with a clean dressing or Band-Aid.

What to do if you suspect you are infected with Vibrio

The most common symptoms of a Vibrio infection are:

1. Pain, swelling, redness and warmth at the wound site.
2. Fever or chills.
3. Significant pain or stiffness in the limb with the wound.

If you experience any of these symptoms after being on the water, go immediately to the hospital emergency room. Time is of the essence, as Vibrio infections can begin within 4 hours of exposure and spread rapidly to the point that serious health risks can occur in less than 24 hours. Inform the physician of the wound, exposure to coastal saltwater and that Vibrio infection is a possibility. The initiation of antibiotics should be strongly encouraged by the patient, even while attempts are made to culture the organism.

Why we need a Vibrio early warning system in Texas

In many parts of the world, Vibrio infections are increasing due to a combination of factors including warming of waters that either allow Vibrio to expand to new locations or that expand the seasonal window of opportunity for its growth, and also simply due to more people heading to beaches and out for fishing. Because of this, we need to better understand when, where and why Vibrio occurs. Unfortunately there is no routine monitoring for Vibrio in Texas, hindering our ability to understand when, where and why Vibrio occurs, which then prevents notification of the public when risk is high such as is done by the Texas Beachwatch program for fecal bacteria: https://cgis.glo.texas.gov/Beachwatch/index.html. In other states with good data, efforts to develop Vibrio “early warning” systems are showing promise. Given the rare but serious impacts of Vibrio on human health, the negative publicity that Texas beach communities receive when an infection occurs, and also the potential to reduce the public’s risk with a robust warning system, we believe that there is merit in the State of Texas investing in a saltwater Vibrio monitoring program. In the meantime, we hope that anglers, beachgoers and anyone venturing out into saltwater can benefit from the recommendations here for minimizing their risk of infection and illness from Vibrio.

Thank you to Samantha Johnston and Rosalie Sanchez for their review of this article.

Take home messages:

1. Vibrio (“flesh eating bacteria”) is a naturally occurring bacteria found in all saltwater environments.
2. Infection is rare but can be deadly if not promptly treated.
3. Risk of infection is most pronounced when water temperature is at or above about 70 degrees Fahrenheit, although infection can occur year-round. Infection risk is also more pronounced during Saharan dust events.
4. To minimize risk, avoid exposure to saltwater when you have open wounds on your body, especially if you are immunocompromised.
5. Treat fresh cuts or wounds that have been exposed to saltwater immediately by washing with antibacterial soap and warm water. Chlorhexidine products such as Hibiclens® scrub provide lasting antibacterial effect. Then apply a topical antibiotic cream and cover with a clean dry dressing.
6. Carry a small bottle of Hibiclens® with you on the water.
7. If you have been exposed to saltwater and suspect that you are developing a Vibrio infection, immediately seek medical care and tell the doctor that you were exposed to saltwater.