Just when you thought it was safe to go back in the water

Forget shark attacks, it’s the oysters that are gonna kill you.

If you go swimming, boating or fishing in the ocean this summer and feel a bit odd within a day or so after, head to a doctor as soon as you can. That’s the key take-way advice from Dr. Blake Ushijima, a postdoctoral researcher at the Natural History Museum’s Marine Station in Ft. Pierce, Fla., who studies the molecular pathogenesis of bacteria that infect marine organisms. In other words, flesh-eating bacteria.

A number of recent cases of flesh-eating bacteria (Vibrio vulnificus) have been reported this summer in Delaware, Virginia and Maryland, so even though your chances of contacting an infection from it are very low, it’s good to exercise extreme caution to avoid the possibility of dying from this aggressive marine bacteria.

Torch writer John Barrat donned his HazMat suit and asked Ushijima a few questions about microscopic threat.

False-color image of Vibrio vulnificus, the so-called flesh-eating bacteria.

What do you know about flesh-eating bacteria and its impact on humans?

I’ve done a lot of work on different bacteria of the Vibrio genus. I’m not an expert on Vibrio vulnificus but I do know the general concepts about it and the infections it causes, generally called vibriosis. It prefers warmer water where it can grow faster. Due to global climate change increasing the duration and spread of warmer ocean water, small outbreaks of this bacteria have been reported as far north as Alaska where it has never before been a major concern. Cases of human infection have been increasing in Florida since 2016 and some fatal infections have recently been reported in New Jersey, Delaware and Virginia.

It is still rare to be infected by Vibrio vulnificus in the U.S. but this is only one of about a dozen species of marine Vibrio bacteria that can infect humans. Infections typically occur by ingesting undercooked or raw seafood, typically oysters. Vibrio bacteria like to affix to and colonize shellfish: oysters and similar organisms, even crabs. Most people with V. vulnificus infections of the gastrointestinal tract usually have symptoms associated with food poisoning, vomiting and upset stomach. These infections tend to be much more severe for people with underlying health conditions, such as cirrhosis of the liver caused by diabetes or alcoholism. Even in healthy individuals, V. vulnificus can make its way into the bloodstream and cause a serious infection, septicemia (blood poisoning).

Outside the gastrointestinal tract V. vulnificus can infect soft tissues such as skin—hence it being commonly referred to as flesh-eating bacteria. Once it infects the skin, it again can move into the blood stream and can trigger a strong reaction from your body’s immune system that leads to death. If individuals are unable to get immediate medical help, death can occur in as little as a day. People normally get a V. vulnificus infection when they get a cut from a shell, which transfers the bacteria into the skin; the wound gets infected, causing the flesh-eating condition. However, simply wading in seawater with an open cut can result in infection.

Does the bacteria actually “eat” the flesh?

The bacteria is essentially breaking down your cells for nutrients so it can be considered a type of eating. The bacteria spread in the warm nutrient-rich soft tissues under the skin causing massive amounts of damage, resulting in necrotizing fasciitis, which comes on fast and spreads rapidly. Symptoms are highly inflamed and painful red or purple skin, vomiting and fever. People usually die of septic shock, which causes a dangerous drop in blood pressure.

Researchers describe 5 cases of Vibrio vulnificus necrotizing fasciitis that occurred after water or shellfish exposure in the Delaware Bay. Via https://www.infectiousdiseaseadvisor.com/

Why does Vibrio vulnificus like to attach itself to shellfish?

Oysters are filter feeders so they pick up V. vulnificus from the environment, and the bacteria can accumulate inside of the oyster. If the infected oysters are not properly stored, the Vibrios in them (which can divide as fast as every 10 minutes) rapidly multiply and infect anyone that eats them. The infected oysters don’t look, taste, or smell any different than non-infected oysters. This pathogen also likes to stick to surfaces such as oyster shells and is especially attracted to chitin, the material that makes up the shells of organisms such as crabs, lobsters, and shrimp.

Does the increased activity of V. vulnificus and other Vibrio bacteria pose a health threat to other organisms in the ocean: fish, marine mammals, birds, as well as humans?

Yes, there are strains of V. vulnificus that are fish pathogens and can threaten aquaculture industries. However, the increasing water temperatures also benefit other pathogenic species of Vibrios, which have been shown to infect a range of different crustaceans, mollusks, fish, and corals. These other species can threaten industries that farm some of these host organisms, but also destabilize ecosystems via disease (vibriosis) outbreaks.

 What is causing this increase in Vibrio vulnificus infections?

Vulnificus infections have been a problem for some time in the Gulf of Mexico where it is warmer, but due to global climate change, warmer waters are moving north into New Jersey, Delaware and the Chesapeake Bay. As I have pointed out V. vulnificus is one of a number of different Vibrio bacteria species and several recent scientific publications have predicted that in the future, we are going to have many more problems with these other species as well, in terms of human infection, whether it be from eating shellfish, skin infections or other problems. Alarmingly, there are also multiple published studies that are already demonstrating a rise in vibriosis cases and a link to climate change.

Oysters infected with V. Vulnificus look, smell and taste no different than uninfected oysters.

What do you recommend to prevent vibriosis?

While V. vulnificus is one of the rarer Vibrio infections, it is the most lethal one. Wash off thoroughly after you get out of the water. If you get any cuts wash them out quickly and very thoroughly. People love eating raw shellfish like oysters. Maybe think twice the next time before eating them during the warmer months.

If something doesn’t feel right, if you are not feeling well, get to a doctor immediately. A lot of V. vulnificus mortalities are from people not seeking medical help soon enough. A doctor can treat your illness with antibiotics and even dialysis for kidney failure, which can occur with immunocompromised patients. Some of the skin infections can can require surgery or even amputation. It is rare for people with healthy immune systems to get an infection, but when they do, they tend to let it work itself out. That is when problems occur.

Dr. Blake Ushijima

Blake Ushijima is a Postdoctoral Fellow at the Natural History Museum’s Smithsonian Marine Station in Ft. Pierce, Florida. He received his bachelor’s degree in biology and a doctorate in microbiology from the University of Hawai’i at Mānoa. He began his research career studying coral diseases that affect reef-building corals in the Pacific and the pathogenic bacteria responsible for them. Currently, he is investigating the stony coral tissue loss disease (SCTLD) outbreak that is devastating the Florida coral reef tract. Specifically, he works on identifying the etiological agent(s) responsible for SCTLD as well as trying to develop probiotic treatments that can treat diseased corals or protect healthy corals held in captivity.

Related posts:

Thinking about impeachment like a historian Our Smithsonian: Backyard archaeology How do you help a Komodo Dragon with arthritis? Mitsitam closing for renovations but Espresso Bar remains open at the National Museum of the American Indian