Vibrio 101: What is it and how can you prevent an infection?

Three people in North Carolina have died in the last month due to infections from vibrio, a bacteria that naturally lives in coastal waters.

The North Carolina Department of Health and Human Services is encouraging North Carolina residents to practice caution in salt water and brackish water — a mix of fresh and saltwater commonly found in estuaries.

According to DHHS, two of the three people who died had scratches that were exposed to brackish water in North Carolina. The third case also had brackish water exposure in North Carolina, however, that individual also ate seafood that was not shared or commercially distributed. Vibrio can cause disease if eaten in undercooked oysters or shellfish.

While vibrio infections are rare, they can cause severe illness, with most cases being reported in the warmest months — June through September.

Rachel Noble, a professor at the University of North Carolina Chapel Hill Institute of Marine Sciences, answered a few questions about vibrio.

What are vibrio?

Vibrio are a genus of bacteria, or a big group of bacteria, Noble said. Within this group of bacteria are a few kinds that are dangerous to people.

About a dozen kinds of vibrio bacteria are known to cause illness in humans. The most common kinds in the United States include vibrio parahaemolyticus, vibrio vulnificus and vibrio alginolyticus, according to the Centers for Disease Control and Prevention.

“The two that we care about in North Carolina are really these vibrio vulnificus and vibrio parahaemolyticus,” said Noble.

Where are vibrio?

Vibrio vulnificus and vibrio parahaemolyticus are ubiquitous in estuaries in North Carolina, South Carolina, Virginia and Georgia, as well as any estuarine system that’s going to be relatively shallow.

North Carolina has thousands of miles of estuarian shorelines, where people do all sorts of activities including shrimping, fishing, crabbing, swimming and paddleboarding. Vibrio vulnificus and vibrio parahaemolyticus are the two species of vibrio that prefer medium levels of salinity.

“In the oceanographic world, we call them mesohaline, meaning that they like middle levels of salt.“ said Noble.

Due to the current heat wave, water bodies in North Carolina are increasing in temperature and increasing the rates of growth of vibrio bacteria, so the numbers of bacteria increase at the same time that people are increasing their recreation and fishing activities, Noble said.

“It’s kind of like a perfect storm,” she said. “Vibrios are taking advantage of the heat, but at the same time human activity is at its peak in these July, August and September months in North Carolina.”

How do vibrio infect people?

Vibrio are among very few bacteria that are capable of infecting people in multiple ways, said Noble. Somebody can get a vibrio vulnificus infection by ingesting it through raw seafood, or by being out in the water and ingesting high numbers of the bacteria.

Vibrio can also infect people with open wounds, cuts or scratches who are exposed through direct contact with seawater or brackish water.

“Those are the kinds of wounds that are particularly at risk,” said Noble. “You have to be proactive about opening that wound and cleaning it out.”

Vibrio growth is known to be boosted by iron, said Noble, so when vibrio enter through the bloodstream they begin to proliferate.

Are vibrio infections on the rise in North Carolina? Why?

Reports of vibrio infections associated with brackish water contact have been increasing over the past several decades, and the locations associated with infection are spreading north along the East Coast due to increasing water temperatures, according to the NCDHHS.

As climate change increases water temperatures, more vibrio cases can be expected, and they are likely to be identified in previously unaffected areas, according to the NCDHHS.

Over decades, Noble has noticed an increase in the number of vibrio infections during hotter summers. While they’re still relatively rare, climate change is increasing the incidence, she said.

However at the same time, human exposure is increasing — there are more people coming to the beach and enjoying different forms of recreation, said Noble, and there are more researchers paying attention to the surveillance.

“It’s hard to understand whether there’s actually statistically more infections, or if we’re doing a better job of tracking the infections that do occur,” said Noble.

What are the symptoms of vibrio infections?

According to Noble, a vibrio infection presents itself as an angry, red and raised wound, with pustules sometimes. Some people will first suffer a low grade fever that can then spike.

She suggested seeing a doctor if there is a fever of 102 or 103 degrees, because that means that the vibrio might have has gotten into the bloodstream and is causing a a kind of septic infection.

Noble recommends making a wound actively bleed by making sure to lift any covering skin so it can purge out bacteria that might’ve slipped in. She said treatment with hydrogen peroxide is a huge recommendation for any suspicion of a vibrio infection.

While healthy individuals typically develop mild illness, vibrio infections can be severe or life threatening for people with weakened immune systems or chronic liver disease. Symptoms can include diarrhea, stomach pain, vomiting, nausea, fever and chills, according to NCDHHS.

NCDHHS recommends that if someone starts to see signs of a skin infection after contact with brackish waters or seawater, they should contact their health care provider.

How can I reduce my risk of exposure to vibrio?

The NCDHHS recommends these actions to help reduce your likelihood of exposure and infection:

• If you have a wound (including from a recent surgery, piercing or tattoo), stay out of saltwater or brackish water, if possible. This includes wading at the beach.

• Cover your wound with a waterproof bandage if it could come into contact with saltwater, brackish water or raw or undercooked seafood.

• If you sustain any type of wound while in salt or brackish water (e.g., cutting your hand on a boat propeller or crab pot) immediately get out of the water and wash with soap and water.

• Wash wounds and cuts thoroughly with soap and water after contact with saltwater, brackish water or raw seafood.

Thoroughly cook all shellfish to an internal temperature of at least 145 degrees Fahrenheit for 15 seconds, according to the U.S. Department of Agriculture.

Vibrio are naturally found, so there’s no way to treat the water to reduce them. In fact, they do very important things in the environment — they metabolize organic matter and help the ecosystem work the way that it’s supposed to, said Noble.

“People should enjoy themselves,” said Noble. “But if they suspect that they have an open wound that was exposed to either brackish water or ocean water, they should come back and be very proactive about washing the wound out and making sure to use hydrogen peroxide to clean it out.”