Potentially deadly infections from a type of flesh-eating bacterium could significantly increase in the decades ahead as climate change causes oceans to warm and helps the organisms spread into new coastal areas.
A study published Thursday in the journal Scientific Reports found that infections caused by Vibrio vulnificus along the eastern coast of the U.S. could double in the next 20 years, particularly as warmer sea surface temperatures enable the flesh-eating bacterium to thrive in waters farther north than ever before.
While V. vulnificus infections are still rare, the findings provide further evidence of how human health and the health of the planet are inextricably linked. The study also adds to a growing body of research on the public health risks that are associated with changes to ecosystems and the environment.
Study co-author Iain Lake, a professor of environmental sciences at the University of East Anglia in the United Kingdom, said he and his colleagues focused on V. vulnificus because it responds to even small shifts in temperature in its marine environment.
“It has been termed a sort of barometer of what’s going on in coastal areas because it is so environmentally sensitive,” Lake said.
V. vulnificus bacteria thrive in warm and shallow coastal waters, and infections typically peak in the summer months. People can become infected through cuts or other lesions in the skin that come into contact with seawater.
Lake called V. vulnificus “a nasty little bug,” because infections spread rapidly and the bacterium can severely damage a person’s flesh. He added that 1 in 5 cases is deadly and that many patients require amputations to survive.
The researchers used data from the U.S. Centers for Disease Control and Prevention to track V. vulnificus infections from 1988 to 2018. The scientists focused on reported cases along the East Coast, which Lake said is known to be a global hot spot for such infections.
The study found that infections increased from 10 to 80 a year over the 30-year period and that cases were occurring in new regions.
The lead author of the study, Elizabeth Archer, a postgraduate researcher at the University of East Anglia, said infections in the late 1980s were mostly seen in Gulf Coast states and areas along the southern Atlantic coast but rarely north of Georgia.
In recent years, the flesh-eating bacterium appears to be migrating north.
“Now the upper limit of our range is around Philadelphia, so it’s a real expansion of where people are being affected,” she said.
That northward expansion is heightened by climate change, because warmer waters allow the bacterium to proliferate, the researchers said. Archer said it’s an example of how changes to the environment can have wide-ranging ripple effects.
“There are these complex interactions between the environment and agents of disease, and it’s important to be aware of the way the world is changing and how these changes are driving risks to human health,” she said.
In their study, the scientists used different models of greenhouse gas emissions to gauge the effect on V. vulnificus infections in the decades ahead. One model envisioned a future with medium-to-high levels of emissions, while the other projected lower emissions as a result of various interventions to slow the pace of global warming.
The researchers projected that V. vulnificus infections will continue to move up the coast and that by the 2040s, they may spread to encompass densely populated areas around New York. The researchers said that in the higher-emissions scenario, around 140 to 200 infections could occur every year and that the bacterium may be present in every state on the East Coast.
Dr. Louise Ivers, the director of the Harvard Global Health Institute, said that while V. vulnificus infections are extremely rare, they are often devastating. Such infections are also difficult and expensive to treat. The study found that V. vulnificus infections cost more than $28 million in treatment per year.
“Sometimes the rarest of illnesses can cost the most to the health care system, especially if they’re unexpected and very aggressive,” said Ivers, who was not involved with the study.
Amy Sapkota, a professor of environmental health at the University of Maryland School of Public Health, who also was not involved with the study, said the findings should be used to raise awareness among the public and health care providers, particularly in parts of the country where such infections may occur in the future.
“It’s critical to get out public health messaging, such as when it’s not advisable to swim or when you should avoid these waters if you have an open wound,” Sapkota said. “We need to get these types of messages out to recreationalists, as well as people whose livelihoods are based on being out on the water.”
Ivers said such research needs more investment for experts to understand the direct links between ecological disasters and human health and how to mitigate the risks.
“We need to ensure that public health systems are resilient and that we understand the connection between what’s happening with the changing climate and what it means for human health,” she said. “This study is focusing on something rare, but it’s connecting bacterial microbiology with what it means for the public health community.”
