'Flesh-Eating' Bacteria: Know the Basic Science Before Going to the Beach

Infectious bacteria have been reported on beaches from Florida to Delaware.

Unsplash / Louis Hansel

Flesh-eating bacteria are having a bit of a moment. Local news reports are rolling in from Florida to Delaware describing serious infections that usually result from some combination of an open wound and a day at the beach. These bacteria can cause serious infections that take a lasting toll on the people affected by them. But knowing the basics about the infection makes the flesh-eating bacteria sound more rooted in reality and less like something out of Stranger Things.

When a bacteria earns the title of “flesh eating,” it typically means that it can cause the skin around an open wound to die. It’s not so much that the bacteria is actually being eaten, per se. Occasionally, that condition can progress to a very serious condition called necrotizing fasciitis. This type of infection is rare but incredibly serious: One in three people who have a serious necrotizing fasciitis infection can die from it, according to the US Centers for Disease Control and Prevention.

These infections can seem very scary, and sadly have already caused fatalities this year.

Fortunately, we know a lot about the two major bacteria behind these infections and how to deal with them.

Two Bacteria Cause Necrotizing Fasciitis

The CDC says that group A Streptococcus bacteria are the most common cause of necrotizing fasciitis in the United States. Tracking infections through an online system, it reports that about 700 to 1,200 group A Streptococcus cases occur each year in the US. Though they can occur after a visit to the beach, these infections have been documented without a dip in the ocean or exposure to seafood.

In 2017, one hiker who mistook the wounds caused by group A Streptococcus for blisters was later admitted to a hospital, where doctors confirmed a case of necrotizing fasciitis. Fortunately, he recovered.

But while group A Streptococcus may be the most common form of “flesh-eating” bacteria in terms of statistics, it’s not the subject of the most recent local news reports.

The Most Famous Flesh-Eating Bacteria

The recent onslaught of reports in the US have come from states as far apart as Florida, Maryland, and Texas. All the cases describe encounters with one flesh-eating bacteria in particular: Vibrio vulnificus.

Vibrio vulnificus, a flesh-eating bacteria responsible for several beach-based infections this year. 

Wikimedia Commons 

These reports all tell a similar story that begins when someone with an open wound goes for a swim in salt or brackish water. Swimming with an open wound is a common way to get that wound infected with Vibrio vulnificus. But infections can also happen from consuming raw or undercooked shellfish.

According to the CDC, Vibrio vulnificus infections occur in about 205 people per year and are treatable with antibiotics. These infections can become very serious: Roughly one in seven people with a Vibrio vulnificus wound infection dies, according to the CDC.

Who is Most Susceptible to Infection?

The people who are most susceptible to both group A Streptococcus and Vibrio include people who already have compromised immune systems or other conditions that can weaken the immune response, like diabetes, cancer, or liver disease.

There’s some evidence, however, that men tend to fall victim to Vibrio infections more often that women do. As James Oliver, Ph.D., a professor at the University of North Carolina, Charlotte who studies aquatic bacteria told Inverse previously, 80 percent of people who get Vibrio infections are men over the age of 40 who are also at risk for liver scarring (cirrhosis).

“This [the frequency of male victims] appears to be because this is the major group of individuals who develop cirrhosis,” Oliver said. “It also appears that estrogen protects females, to some extent, from the toxin V. vulnificus produces.”

How to Keep an Eye Out For Both Types of Infections

No matter what “flesh-eating” bacteria is responsible for an infection, the guidelines to help avoid them are the same. Staying safe really comes down to being responsible about wound care and acting quickly at the first sign of an infection. Symptoms usually include red swelling around the wound, pain in the area, and fever.

To avoid these infections altogether, the CDC advises staying out of salt or brackish water if you have an open wound or, at the very least, wrapping that wound up tightly before entering the water.