This week a skin infection that occurred after wading in the Gulf of Mexico made headlines, not only because it had an unusual cause but also that it quickly turned deadly. The wife of the Palm Coast, FL man who died from the infection said that her husband had what looked like a small spider bite on his ankle which began to spread, prompting a trip to the hospital. In just a few days the infection had spread systemically, causing his death.
The cause of the infection was a common type of bacteria found in warm salt water, called Vibrio vulnificus. These are the bacteria behind the warnings to avoid eating raw shellfish, to decrease your chances of contracting a nasty and potentially fatal gastroenteritis. V. vulnificus can in some cases cause serious skin infections, although this is very rare--to date only 31 cases of V. vulnificus infection have been reported in Florida.
The ankles and feet are common sites for small, unnoticed abrasions or tiny wounds, making them susceptible to any type of infection. Other factors can increase the chance of infection, such as health conditions that compromise the immune system or poor leg circulation. It's also common for infection symptoms to look like small insect bites.
More about how bacterial infections can appear on the foot and ankle: Bacterial Infections of the Feet.
Source: 31 in Florida infected by bacteria in salt water. Fox News.com. Accessed 10/13/13.