With the release of the trailer of Brad Pitt's new film World War Z, it would seem a zombie apocalypse is very much in the realm of fiction.
However, this may not be the case, as scientists have discovered a fungus that feasts on human brains.
The fungal meningitis pathogen, named Exserohilum rostratum, is generally plant-eating and is equipped with a spore-launching mechanism ideal for going airborne. The fungus is not a picky eater and while it prefers grass, it will happily eat human brains.
The mystery surrounding this zombie fungus - and a question baffling scientists - is how it got into three lots of injectable steroids prepared inside a laboratory (which was filthy), but also why it only got into just three lots - and not more.
In an article by the Scientific American, published by the Nature journal, the authors note that the US is currently experiencing a fungal meningitis outbreak that has so far killed 30 and made 419 ill.
The fungus was found growing in unopened vials of the steroid that was believed to have caused the outbreak, the US Centre for Disease Control and Prevention said.
Glenn Roberts, a retired medical mycologist, said that despite his 40-year career at the Mayo Clinic in Rochester, Minnesota, he was shocked to hear the identity of the pathogen.
"I could hardly believe it because it's just so uncommon," he said.
Despite this, he was not surprised that the fungus would capitalise on its situation after finding itself inside a patient. The fungus was injected into the dura, the space between the dura mater (which encloses the spinal fluid), the spinal cord and the inside walls of the vertebrae.
The fungus was able to enter the spinal fluid and then go into the brain; where the immune system has difficulty eliminating or controlling infection.
Roberts said: "Spinal fluid is a great culture medium - one of the best. The nutrients are there, and the temperature is certainly right."
In some of the fatal cases, the fungus began to grow in the brain.
How the fungus got into the three vials is in question. Scientists think that if the facilities air or water supplies were contaminated, more samples would be affected.
Roberts hypothesised that something may have blown in from a nearby recycling centre.
Another other theory is that the water used for making the final doses of the drug was not sterile. "Using nonsterile components [for injection] in somebody's spine? My goodness, that's terrible," he said.