Necrotizing fasciitis: The 'flesh-eating' infection that bores holes in the body

Disease name: Necrotizing fasciitis, also known as "flesh-eating disease"

Affected populations: Flesh-eating disease can affect anyone. It occurs in about 0.4 in 100,000 people in the U.S. each year. The disease is most commonly seen in people with conditions that weaken the immune system, such as cancer, liver scarring (cirrhosis), diabetes and kidney disease.

Causes: Necrotizing fasciitis is caused by one or more bacteria infecting the fascia, the connective tissue that runs below the skin. Fascia also surrounds organs of the body, helping to hold them in place. Often, flesh-eating disease is caused by Group A streptococci bacteria, such as Streptococcus pyogenes. But other bacteria — like Staphylococcus aureus, Klebsiella and Escherichia coli — can trigger the infection.

These bacteria get into the connective tissue, either through an external injury or from a ruptured organ. They then release substances that restrict the blood supply to the infected tissue and begin "eating," or digesting the cells within it. This causes pus-filled lesions containing dead cells to form. If treatment is delayed, the infection can trigger deadly conditions such as sepsis, organ failure or toxic shock syndrome.

Related: Decades-long mystery of flesh-eating, ulcer-causing bacteria solved

Symptoms: Early symptoms of flesh-eating disease often resemble those of the flu, such as body aches, fever, chills and nausea. Patients may also experience intense pain and swelling near an infected cut or wound, if that's how the bacteria entered their body. Symptoms can then quickly progress within hours or over a few days as pus-filled blisters begin to form at the wound site and tissue is destroyed, causing it to turn black. The disease can also cause delirium, extremely low blood pressure, and a rapid heart rate. In late stages of the disease, a patient's vital organs may shut down, leading to death.

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Treatments: The only way to treat necrotizing fasciitis is to surgically remove any dead or infected tissue. This often necessitates the amputation of one or more limbs. Patients are also given antibiotics to help kill the bacteria. The Centers for Disease Control and Prevention estimates that, even with proper treatment, up to 1 in 5 people with necrotizing fasciitis die.

Recent cases: In 2023, a 58-year-old man in Madrid developed necrotizing fasciitis in both legs, but not at the same time. Doctors initially gave him antibiotics and surgically removed infected and damaged tissue from his right leg. Four days later, they found that the bacteria that caused his infection (S. pyogenes and S. aureus) had also spread to his left leg. Thankfully, after another round of surgery and antibiotics, the man was cured and discharged from the hospital a month later.

Also in 2023, a 52-year-old man in Florida was infected with "flesh-eating" bacteria in his left thigh after being bitten by a relative during a fight at a family gathering. He eventually recovered from the infection, but he had to have 70% of the tissue from the front of his thigh removed and was left with heavy scarring.

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