A dangerous bacterium from the Vibrio genus is spreading through the Mediterranean Sea, causing an infection called vibriosis. Spanish authorities have already closed several beaches due to this threat. The bacterium enters the human body through consumption of improperly processed seafood or through open wounds. Symptoms include diarrhea, vomiting, abdominal cramps, fever, and chills. The most dangerous species is Vibrio vulnificus, with a mortality rate of 20 to 50 percent, particularly affecting elderly people and those with weakened immunity. Bacteria multiply in warmer water, which is why their occurrence increases during heat waves. Prevention includes thorough heat treatment of seafood, maintaining personal hygiene, and avoiding swimming in salt water for people with open wounds.