A trip to the beach can be delightful. But as with all outdoor activities, there is some risk. Sunburn, rip currents and foodborne illnesses are well known, but Vibrio bacteria are not.
Some Vibrio strains can cause skin infections and gastrointestinal distress, known as vibriosis. In extreme situations, infection can lead to death. For the vast majority of people, however, the risks can be minimized, says Rachel Noble, PhD, an environmental molecular microbiologist at the UNC Institute of Marine Sciences.
Taking simple steps will help protect you and your family from vibriosis, she says. Here are answers to some common questions.
Where do Vibrio live?
Vibrio bacteria are most plentiful in estuaries where fresh water from rivers mixes with salty water from the ocean, creating brackish water. Estuaries include sounds, salt marshes, bays and tidal creeks, where people enjoy fishing, shrimping, clamming, paddleboarding, kayaking and swimming.
Although Vibrio are present in the ocean, “the concentration of the ones that can cause human infections is much higher in estuaries,” Dr. Noble says.
Vibrio strains also may be found in raw seafood, especially shellfish such as oysters and clams, which are filter feeders and can concentrate the bacteria.
How common is vibriosis?
According to the Centers for Disease Control and Prevention (CDC), vibriosis causes about 80,000 illnesses each year in the U.S., about 8 in 10 of which occur between May and October, when water temperatures are warmest. About 52,000 of the total cases are caused by eating contaminated food.
How do you get vibriosis?
You can get infected with Vibrio by swimming in water when you have an open wound, such as a cut or scrape, or if you’ve had a recent piercing or tattoo.
You can also get vibriosis by eating raw or undercooked shellfish, such as oysters, clams and mussels. Swallowing water that contains a high concentration of Vibrio can lead to an infection, too.
Who is at greatest risk of vibriosis?
People who are immunocompromised or have chronic liver disease, diabetes, poor circulation or similar conditions are more likely to develop serious infections, Dr. Noble says. “If the body can’t clear the bacteria more quickly than it multiplies, then the infection will spread,” she says.
The CDC suggests that anyone at high risk consider wearing clothes and shoes that protect against cuts and scrapes when in saltwater or brackish water. They should also wear protective gloves when handling raw seafood.
Dr. Noble says men are more likely than women to develop serious infections because, in general, men have a higher level of iron in their blood, which Vibrio use to multiply faster.
People age 50 and older are at greater risk, she says, because they are likelier to have chronic conditions.
What are the symptoms of vibriosis?
If a wound is infected, the skin may become red, swollen and painful. Pus-filled blisters (pustules) may appear. A low-grade fever may be an early sign, and the fever may spike.
Other symptoms of vibriosis are diarrhea, nausea and vomiting, stomach pain, fever and chills.
If your fever reaches 102 degrees or higher, see a doctor immediately. High fever is a sign that the Vibrio might have entered the bloodstream and are causing a septic infection.
If a wound is showing symptoms of Vibrio infection, treat it immediately or get medical attention. The infection can get worse very quickly. You should never go to bed if you are concerned about a serious Vibrio infection, as it can progress rapidly.
How can vibriosis be prevented?
The first line of defense is cleaning wounds with soap and water after exiting the water, Dr. Noble says. Then, disinfect the area with an antiseptic such as hydrogen peroxide or povidone-iodine.
“Don’t cover the wound until it is completely clean,” Dr. Noble says.
Once you are confident the wound is clean, you can add an antiseptic cream or ointment. It’s a good idea to have this product handy in your first-aid kit.
The CDC offers these recommendations:
- Stay out of saltwater or brackish water if you have a wound.
- Cover your wound with a waterproof bandage if there is a possibility it could come in contact with saltwater, brackish water, raw seafood or raw seafood juices.
- Wash your hands thoroughly with soap and water after handling raw shellfish.
- Make sure any seafood you eat is fully cooked.
- Avoid contaminating cooked shellfish with raw shellfish and its juices.
Dr. Noble says, “Whatever you do, don’t wash out a wound with seawater.”
How do you treat a vibriosis infection?
If you’ve taken preventive measures but still develop vibriosis, get medical help as soon as possible. “Tell them you’ve been exposed to salty or brackish water,” Dr. Noble says.
Antibiotics—delivered as a pill, IV or shot—can be effective in treating vibriosis, especially if you get them before the infection is advanced.
“Rather than being afraid of going into the water, enjoy yourself,” Dr. Noble says. “Just be proactive when you come out of the water.”
If you’ve been exposed to salty water or have eaten shellfish and show signs of a vibriosis infection, see your doctor immediately. Need a doctor? Find one near you.