It's a common staple in any zombie movie: one minute, you're surrounded by mild-mannered family, friends and strangers and the next, these same people are chasing you down, trying to eat your flesh. While this makes for great horror movie fare, for hundreds of people each year, this scenario is a terrifying reality.
The only difference is that instead of people, these friends-turned-enemies are germs.
The microbial attack is officially known as "necrotizing fasciitis" (pronounced fash-ee-i-tis) although it is better known as flesh-eating disease, with good reason. The main symptom is death (necrosis) of the underlying layers of the skin (fascia) either in one localized area of the body or, as the condition worsens, the extremities, the torso and the organs.
The usual outcomes are debridement, in which the dead flesh is literally cut away from the body; amputation to remove larger areas that cannot be saved; or, if not treated quickly enough, death.
The good news is that necrotizing fasciitis is rare and only a handful of germs, specifically bacteria, can cause this illness. Yet in the last month one woman's plight with the infection has put it in the national and international headlines.
Aimee Copeland, a 24-year-old from the Atlanta suburb of Snellville, Georgia, was making the best of a beautiful May afternoon by kayaking and zip-lining on the Little Tallapoosa River. Unfortunately, the zip line broke and Copeland fell into the river cutting her calf. She sought medical attention and the wound was treated and closed. But a specific bacterial strain that she encountered in the water survived and started a horrific cascade.
Within 72 hours, the infection had caused significant damage and Copeland's leg had to be amputated. But even that was not enough as the bacteria spread to her other leg and to her fingers. They too would be eventually amputated. The damage left her in critical condition, which worsened as her organs began to fail. It would be another two weeks before the medical staff could control the situation and give Copeland a fighting chance at life. Mercifully, as of Sunday, she was talking on her own and can be listed officially as a survivor despite losing her leg and extremities.
Copeland's tragic encounter with death is worsened only by the revelation that the cause of her troubles was not some menacing pandemic-threatening plague, but rather a normally harmless freshwater bacterium known as Aeromonas hydrophila. The reality is, however, that most of the causative culprits of this misery are usually beneficial to us; many live on our bodies or in our guts as normal flora. It is only when they penetrate past the skin and into the fascia, usually through a wound or puncture that these allies change and become vicious hungry beasts.
Once there, the process is simple and lightning fast. The invaders first start to feed on the available sustenance, such as amino acids, salts, sugars, and lipids and keep the flow coming by producing a toxin that breaks down cells that release their inner nutrients. When that area starts to become depleted, they spread to other parts of the body in the hunt for more food.
Not surprisingly, the body reacts to this intrusion, known as sepsis, by triggering the corporeal version of the military, the immune system, to kill the intruders. Yet these creatures have a leg up on their human zombie counterparts as they produce one or more proteins that stop the immune system in its tracks and force it to inadvertently attack the body's bystander cells. The pace of necrosis increases exponentially and the patient's condition worsens dramatically. For about 30 per cent who suffer from this ailment, the situation is hopeless: The zombie germs win and the patient tragically dies.
Since Copeland's story went public, two more cases have been reported, one of which happened in the same hospital that treated her. Others who have suffered are also coming forward, relating their struggles with their once-friendly flora. While this may appear to signal the onset of an upcoming flesh-eating pandemic, the reality is that the rise is due more to media attention rather as a result of incidences.
Necrotizing fasciitis affects between 500 and 1,000 people in the United States and Canada each year and that incidence hasn't changed in several decades. Even more importantly, the majority of cases are non-transmissible, meaning that the infection cannot spread from human to human unless there is a significant wound transfer. A zombie germ apocalypse is therefore highly unlikely unless infected humans start to cut, slice (or bite) others in the hopes of spreading the syndrome.
Thankfully, that only happens in the movies.