A Guest Post: The Biology of Zombies: A Primer – Part 2
Fungi are a very diverse and interesting group. At the mention of fungi, most of us think of mushrooms sprouting in our yard. But there are a few species that are very animal like, able to move through the environment in order to acquire food. Most fungi are decomposers, breaking down dead organic matter, while others are parasitic. The Cordyceps fungi (or more accurately, Ophiocordyceps) is famous for making the “Zombie Ant”. In this case, the fungus infects the ant, changes the behavior of the ant and causes the ant to die. The fungus then produces a fruiting body that disperse more spores to infect other ants. Creepy right? How about this: this isn’t the only case. There are actually quite a few different species of Cordyceps and each have a specific host insect. The recent video game “The Last of Us” plays off this idea of a zombie fungus.
Probability: Fungi have a difficult time living inside our body. Many of our allergies are caused by fungal spores, and a rare few cause illness due to getting into our body. The most recent I have heard is from the Pacific Northwest in which a yeast is causing some severe respiratory illness. But as before, getting past our immune system and being specialized enough to cause “zombie-like” symptoms is a difficult thing to do. My best guess for a “Fungal Zombie”: a fungal infection of an orifice that would be able to secrete a chemical that enters the bloodstream, altering our behavior. Currently, there has been nothing even close to that. So for now, we can relax.
Prions and viruses are zombies of the microbe world. They way these two operate are the epitome of zombie lore. Prion research is booming, as we know little about them. The term “prion” is short for proteinaceous infectious particle, meaning a protein that acts as an infectious microbe. But that term is changing because we are learning there are good prions as well. What is really unique about a prion is that it is a nonliving particle. It is simply a protein in cells. Our cells machinery produce many different proteins that help to regulate our body; Insulin, for example, is a protein in blood sugar regulation. They are like one of our bodies little messengers. You probably know prions in a different example: Mad-Cow Disease. We too have our own Mad-Cow, called Creutzfedlt-Jakobs Disease. Both of these diseases are caused by abnormal proteins causing normal proteins to change to the abnormal form. Very much like a zombie biting someone to make another zombie. These prions basically kill neurons (brain cells) causing brain degeneration. This was first described in humans when a cannibalistic tribe began showing symptoms after consuming their dead. By eating infected flesh, particularly brain matter, these prions can be transferred to those eating it. And to really freak you out, people can spontaneously begin producing these abnormal proteins. Current research is beginning to link other types of rogue prions to Alzheimers disease and Parkinsons.
Probability: Well, this one is a toss up. Although we can see zombie like symptoms, it lacks the bite attack we see in zombies. The other problem is that a bite most likely would not transfer the prion. But for now, this is the closest we have to a living, breathing zombie. Not quite undead, but definitely lumbering, possibly anger or rage, hallucinations, and shuffling. The possibility of this becoming an epidemic is slim. If you want to stretch the imagination, we could assume an agent could “turn-on” these abnormal prions in the masses, but I think we would still lack the zombie we have grown to love in the movies.
Next: Viruses – Our Worst Fear