What you need to know about Vibrio bacteria

(CNN) – A number of recent reports have warned the public of the dangers of Vibrio bacteria from eating certain foods or swimming at the beach. An infection can lead to gastrointestinal problems, limb loss and even death. But what are these bacteria?

"These are interesting organisms and range from the massive global epidemic – cholera – to infrequent but deadly infections – Vibrio vulnificus," said Rita Colwell, a professor in the Department of Cell Biology and Molecular Genetics. the University of Maryland. and former director of the National Science Foundation.

There are about 12 species of Vibrio bacteria that cause diseases in humans, known as vibriosis, according to the United States Centers for Disease Control and Prevention. About 80% of infections occur between May and October, when the waters are warmer, and usually after a person eats infected shells.

Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio alginolyticus are the three most common species that cause the disease in the United States, reports the CDC. Another notable strain, Vibrio cholerae, is not prevalent in the United States.

Symptoms of Vibrio infection include watery diarrhea, abdominal cramps, nausea, vomiting, fever and chills. Treatment is not always necessary, and serious illness is rare, but doctors prescribe antibiotics in more persistent cases, according to the agency.

Vibrio parahaemolyticus is the most commonly reported species, responsible for 45,000 of the 80,000 Vibrio Diseases per year in the United States, according to the CDC.

"It is associated with the ingestion of seafood that has not been properly cooked, or properly stored and then not properly cooked," Colwell said. "And also by taking oysters or seafood in contaminated areas, which sometimes people do, especially in Florida or the Gulf, where there is a sign that says" no fishing "but the oysters are growing and growing . eat them. "

Vibrio alginolyticus generally causes ear infections and the swimmer's ear, said James D. Oliver, a professor of microbiology at the Department of Biological Sciences at the University of North Carolina at Charlotte.

"Personally, this is not something that concerns me at all," said Oliver, who is also a member of the American Academy of Microbiology.

Vibrio vulnificus, however, is an infection to be wary of, he said.

Bacteria reside in seafood and brackish water (fresh and salt water). They can cause an infection of the skin when cuts and open wounds are exposed to contaminated water. There are about 205 infections a year, says the CDC, but one in four people die, and some have to undergo amputations to stop the spread of infected tissue. Vibrio vulnificus is sometimes mislabeled as a "flesh-eating" bacterium, although it damages the skin.

Vibrio vulnificus is very sensitive to antibiotics, but the drug must be given quickly, in a day or two, said Oliver. If there is an indication of infection such as redness and swelling, a person should consult a doctor, he said.

Very young, very old, and individuals who have suppressed immune systems or high levels of iron in the body are particularly at risk, said Colwell.

"In people who have liver disease – which could be hepatitis or cirrhosis or some other liver disease – these are chronic conditions that are damaging to the liver," said Oliver. "Its cells are destroyed, releasing iron into the bloodstream, and the iron released exceeds the capacity of your blood to sequester it. So, you essentially get free iron in the blood, and this allows these bacteria to proliferate very, very quickly "

Paul A. Gulig, a professor in the Department of Molecular Genetics and Microbiology at the University of Florida, noted that "for raw oysters, most people who become seriously ill have predisposing conditions. … you can be healthy and catch the wound because you are introducing the bacteria into your tissues. "

CDC recommendations to reduce the risk of any form of Vibrio infection include not eating raw or undercooked crustaceans, especially oysters and avoid swimming in brackish and estuarine water if you have broken skin. .

Although Vibrio cholerae is not a major health problem in the United States, there are between 1.3 and 4 million cases of cholera and up to 143,000 deaths a year worldwide, according to the World Health Organization.

"If people are traveling to places where it is endemic, they can pick it up and bring it back," Gulig said. "But it's not an illness that people catch when they're in the US, we do not have it in our water and our food, it's mostly a disease of the people." developing countries due to poor sanitation and poor hydration. "

Most people who are infected have no symptoms or are mild to moderate. Cholera also causes watery diarrhea that can be treated by replacing fluid loss with water and electrolytes and sometimes with antibiotics. If left untreated, severe dehydration can result in death within hours.

"For cholera, I would say that people who go to endemic areas, travel abroad, should look and see what are the CDC's recommendations on vaccination, because there are new vaccines, "said Gulig.

Changes in recent years in Vibrio tests, from bacterial cultures to new tests that may offer less information on the strain of Vibrio causing infection, have made it difficult for the CDC to compare changes in Year after year, said Karen Wong, doctor at the agency.

"But we have noticed that over the years we have seen Vibrio infections in places we have not seen them before," Wong said, highlighting infections in the more northern parts of the country. country.

Some experts claim that warmer climates account for the increase in infections, calling it the microbial equivalent of a canary in a coal mine.

"With warmer temperatures, Vibrios proliferate," said Colwell. "They're getting bigger, and they're outperforming their competitors who at lower temperatures would keep them in check."

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