The record-breaking summer in the Northern Hemisphere this year might somehow be even more miserable than expected. The Centers for Disease Control and Prevention is now warning doctors and the public to watch out for life-threatening infections caused by “flesh-eating” waterborne bacteria. While still rare in general, these infections have become more prevalent in more parts of the U.S. over time as the climate has warmed. This summer, several coastal states have reported cases that have coincided with widespread heatwaves.
The bug in question is called Vibrio vulnificus. There are several species of Vibrio bacteria that cause human illness, with the most infamous of these diseases being cholera. People usually catch these bacteria from eating undercooked or raw shellfish, and most infections are mild or self-limiting.
But V. vulnificus is usually contracted from having open wounds exposed to the water. And when these wound infections happen, they can quickly take a turn for the worse and cause a life-threatening condition called necrotizing fasciitis, also sometimes called the “flesh-eating” disease (the nickname is a misnomer, since the flesh around the wound dies, but isn’t literally being eaten by the bacteria). Only about 150–200 cases of V. vulnificus are reported each year to the CDC, but one in five people will die from it, sometimes as quickly as one to two days after becoming sick.
V. vulnificus typically lives in warm salt or brackish waters off the coast, and most cases tend to happen during the summer around the Gulf Coast states like Louisiana and Mississippi. But as with many other infectious diseases, climate change appears to have made these infections a more frequent and widespread problem. A recent study in March, for instance, found that reported cases in the Eastern United States increased eightfold from 1988–2018 and that the range of cases has expanded northwards by around 30 miles every year during that time period. This summer seems to have provided even better conditions for the bacteria to cause trouble.
The CDC’s health advisory, released last week, focuses on recent reports of severe or fatal V. vulnificus infections tied to warming coastal waters. The advisory specifically highlights several cases, including six deaths, documented in Connecticut, New York, and North Carolina. Notably, these cases have occurred during widespread heatwaves and above-average coastal sea surface temperatures recorded throughout July and August 2023.
It will take time to confirm whether this year has truly seen a national increase in V. vulnificus cases. But given the long-term climate trends, it will become a bigger threat in the near future. That same March study also predicted that the annual number of cases could double within the next 20 years.
The CDC is advising doctors to be on the alert for cases that could potentially be V. vulnificus, especially given the need for urgent treatment. And it’s warning people at higher risk for illness, such as those with weaker immune systems or conditions like diabetes, to be especially careful this summer. Most importantly, if you have an open wound, you should avoid salt or brackish water entirely until it completely heals, or at least wear waterproof bandages.
“Amid increasing water temperatures and extreme weather events (e.g., heat waves, flooding, and severe storms) associated with climate change, people who are at increased risk for V. vulnificus infection should exercise caution when engaging in coastal water activities,” the CDC said in its advisory.