Contaminated floodwater swirls with risk for serious infection
Aging fat men who fish or swim on the coast this summer should be aware that a nasty microbe lurks in the water, looking for out-of-shape guys to infect with potentially lethal toxins.
The microbe, called vibrio, has grown more prevalent in brackish coastal waters during the past 20 years as the earth’s climate has changed, exposing swimmers and fishermen to its unpleasant effects.
Vibrio bacteria can wash into open cuts and rapidly worsen, causing swelling and massive infections. They also can seep into wounds, get into the blood stream and attack the liver, causing people with low-grade liver diseases to become sicker, according to researchers at the University of South Carolina.
Those most at risk are people who already are ill or who have developed a minor liver disease that often results from poor eating habits — and no group appears more susceptible to liver problems than overweight men on high-fat diets, USC scientists say. Because of their metabolism and physiology, obese men over 40 years old appear more at risk of developing health problems from vibrio exposure than women and younger people, USC research scientist Geoff Scott said.
“That is what the data show, that older males are most susceptible to vibrio wound infections,’’ said Scott, who is leading a national effort by five universities to study how climate change and oceans affect human health.
Scott and Saurabh Chatterjee, who directs USC’s environmental health and disease laboratory, said it’s too early to make final conclusions on the risk of vibrio to older men because research at USC is ongoing.
But nationally, nearly 70 percent of vibrio-related illnesses occur in men, according to one 2018 study by USC researchers. And the median age of people sickened by vibrio is 48, according to statistics reported by the U.S. Centers for Disease Control and Prevention.
Healthy people who eat well, and do not have any traces of liver disease or other ailments, are less likely to get vibrio infections if they go swimming with open cuts. But everyone should know the risk if they have a wound and plan to swim or fish on the coast, experts say.
Vibrio are most abundant in warm brackish tidal rivers that attract people who like to fish, crab and shrimp. Under certain conditions, such as after heavy rainfalls, the bacteria also can exist in the surf where people swim, according to researchers at Florida Atlantic University. That’s worth noting in a state with resorts like Myrtle Beach and Hilton Head Island, which attract millions of visitors each year.
“The beach season is about to begin,’’ USC’s Scott said. “We’ve got to let people be aware and know about this because we may save a life along the way. You never know.’’
Anyone who develops an infection in a cut after exposure to salt water should seek immediate medical attention because vibrio can spread quickly, experts say. One strain of vibrio, called vulnificus, is so dangerous it can kill people within a day or two, according to the U.S. Centers for Disease Control and Prevention. Sometimes people must have limbs amputated to avoid a life-threatening spread of the infection. To avoid the risk, people should bandage cuts securely if they expect to come in contact with sea water, experts say.
Meanwhile, people who are overweight should consider getting tested to determine if they have non-alcoholic fatty liver disease, an ailment that can turn into more dangerous liver ailments when exposed to the vibrio bacteria, Scott said.
Non alcoholic fatty liver disease often results from over-eating and a high-fat diet, just like excessive drinking causes liver damage, experts say. That’s one reason for overweight men to pay attention, they say.
The research Scott’s group is conducting will attempt to predict when outbreaks of vibrio and toxic algae occur so that people can avoid contact with the water. Researchers also are trying to determine if the bacteria are becoming more toxic in South Carolina and other states so that they can warn the public.
Infections linked to all types of vibrio bacteria jumped 41 percent from 1996 to 2005, research shows. Since 2005, the estimated number of vibrio infections in people has increased from about 8,000 cases nationally to 80,000 cases, according USC and the Centers for Disease Control.
In two studies last year, scientists said rising ocean levels and higher water temperatures are contributing to the threat. With the earth’s climate warming and sea level rising, salty water is moving farther into coastal rivers, including the Waccamaw west of Pawleys Island, making conditions right for the expansion of certain vibrio species. Warmer temperatures and sea level rise also are causing the microbe to grow over longer stretches of the year in places it has never been before. It is expected to live longer in the fall and winter in areas like South Carolina than in the past, they say.
One June 2018 study singled out the Waccamaw River as a place where vibrio are becoming a threat. The river, which runs from the North Carolina border to Georgetown, is expected to change from fresh to brackish water at certain times of the year farther upstream, causing a nearly 300 percent increase in exposure risks from the vibrio bacteria, according to the study, published in the scientific journal “Estuaries and Coasts.’’
Scientists have known for generations that some forms of vibrio can make people sick from exposure to polluted water. Cholera is a form of vibrio, for instance. Other strains of vibrio also are major causes of illnesses and death in people who eat raw or undercooked seafood, such as oysters. All told, 22 to 25 people die each year from vibrio infections, mostly after they’ve eaten raw shellfish, studies show.
In recent years, however, researchers have learned more about the threats of vibrio to people with open cuts who are exposed to sea water. Vibrio exposure can sometimes turn people’s arms and legs black with infections — one North Carolina man had his leg amputated two years ago after vibrio infected a cut — or damage their livers. Last year, a Virginia resident and a New Jersey resident died from vibrio infections, according to a report in The Washington Post.
The threat of vibrio to people on high-fat diets with low-level liver disease should be of particular concern in South Carolina, where researchers say many residents routinely eat inexpensive, fatty food. The Palmetto State has the 10th highest adult obesity rate in the country, according to the latest State of Obesity report, an annual study that examines national trends. At the same time, South Carolina ranks 12th nationally in the death rate from liver disease, according to the Centers for Disease Control and Prevention.
USC’s Chatterjee, who formerly worked at Duke University, said liver disease can be an unknown problem, often until it is too late to do anything.
“It is very silent in nature,’’ he said. “Nobody will be given a clue when fatty liver has been transformed into cirrhosis.’’
Research now underway at USC is part of a national effort to learn more about how climate and changes in the ocean are affecting people’s health. USC, Baylor University, the University of Maryland, the College of Charleston and The Citadel are involved in the project that got off the ground last year. Scott and Paul Sandifer, a former director at the S.C. Department of Natural Resources, are leading the effort. The research is being funded through a $5.7 million grant from the National Institute of Environmental Health Sciences.