Types of Zombies Part 2 - Zombification Via Infection

The other classic movie scenario we've all heard is the one where somehow an infected carrier goes on an instict-fueled rampage, biting uninfected civilians and effectivaly spreading the disease. There are two diseases in particular I will be discussing: O. unilateralis and rabies. (I will discuss a rabies-like virus in another post)
O. unilateralis is a parasitic fungus known to manipulate the brains of insects, ants in particular, as it makes an ant decimate the entirety of its own colony. It makes slave-like "zombies" out of its host by recognizing the brains of the different insect species, and in reaction to their species, releases its mind-controlling chemical cocktail into the host's system that eventually travels to its brain. "Behavioral manipulation is such a complex [characteristic] that it only occurs when there's a very close co-evolution between pathogen and host," said Charissa de Bekker, a molecular biologist at Pennsylvania State University and lead author in the journal BMC Evolutionary Biology.
Here is a video link of the fungi affecting an ant in action.
Once an insect walks through some of its fungal spores, the fungus bores its way into the insect's body and eventually takes over its nervous system and its brain. In ants in particular, he fungus makes the ant climb up a nearby plant stalk bite into a leaf nearest to its former colony. The ant soon dies and a long, mushroom stalk breaks through its skull and grows from out of the back of its head, which then releases fungal spores into the air so that they will float down on to the colony below to infect the rest of the colony.

Here's an image of a worker ant that was infected and climbed to a leaf above its colony and sprouted spores. Sorry if your're squeamish to these kinds of things, I am too: I nearly threw up just finding this picture on google images. This is one of the less horrifying-looking ones.

‘What’s rather spectacular in the case of the zombie ant fungi is that they are able to precisely control the behavior of the host before it dies,’ said disease biologist David Hughes, assistant professor of entomology and biology at Pennsylvania State University, who has followed these intriguing organisms all around the world. They can be found in many forests of several countries, such as Thailand, China, Australia and Brazil.

 He described what happens when a spore first attaches itself to an insect on the forest floor. “It does a rather interesting thing – it sticks tight so it can’t be pulled off and then it uses enzymes and pressure to blow a hole through the insect’s body.”

After two weeks growing inside the insect, the fungus is able to control its behavior and produces chemicals that make the ant to go through the process to infect its colony. Dr Hughes is currently preparing a report which identifies how exactly these chemicals work. ‘It’s one of the most complex examples of parasites controlling animal behaviour that we know about.

 This example of nature at its most brilliantly and disgustingly devious sounds like something more suitable to science-fiction. It is the perfect premise, then, for a horror video-game.

The Last of Us, developed by Naughty Dog and exclusively available on the PlayStation 3 and Playstation 4 console systems, takes the Cordyceps concept (the infecred “zombies” of the game”) and pushes it to its limit. The game is set 20 years after a fungal parasite mutated to infect mammals and had taken out most of humanity. Players take the role of survivors battling to survive in a world of grotesque, fungus-faced creatures that are driven by this parasite to infect as many as it can.

Dr Hughes pointed out that fungi are more closely related to animals than they are to plants. He also worked as a consultant to the game-makers.

‘They gravitated towards the idea of growth and they liked the grossness of it,’ he revealed.

Suddenly the walking dead walkers aren't all that scary to me after looking at these monstrosities Naughty Dog's talented game artists designed. Now if you'll excuse me I need to work on my Bubble-Boy style anti-spore suit because mushroom spores are airborne and I am not gonna turn into that thing. 

But the big question is, could a parasitic fungal pandemic as depicted in The Last of Us really happen?

“It’s a flight of fancy to think one of those parasites will be a specialized fungus that only affects ant behavior but the history of medicine shows us that there’s lots and lots of parasites jumping over from animals into humans and then having crazy effects,” said Dr Hughes.

“We constantly inhale billions of spores of fungi every day and our immune system is very well set up to prevent these infections. And we do occasionally see fungi jumping the species barrier, going from one animal into humans.”

He said Aids sufferers in South East Asia have died from fungal infections contracted from small mammals.

In parts of the US, the fungal disease coccidiodomycosis – or Valley Fever – kills hundreds of people a year after it is contracted from spores swept into the air from soil.

“It’s foolish to to think we’re living in a sanitised world protected from mass outbreaks,” said Dr Hughes, before listing examples such as influenza, bird flu, and SARS. 

So is it? That's more up to you to decide based on the evidence I can provide. 

Types of Zombies Part 1 - The dead rising from their grave

We've all heard of the classic movie scenario where the dead corpses infected with a parasite or virus of some sort rise from their graves and shamble into the city in their funeral garb to attack the civilians because of their apparent jealousy for the living's functioning flesh and braaaaains. And there actually are instances in which people proclaimed dead suddenly "came back to life"; however they didn't come back as man-eating "zombies".
In 1999, a Swedish medical student named Anna Bagenholm lost control while skiing and landed head first on a thin patch of ice covering a mountain stream. The surface gave way and she was pulled into the freezing current below; when her friends caught up with her minutes later, only her skis and ankles were visible above an 8-inch layer of ice.
Bagenholm found an air pocket and struggled beneath the ice for 40 minutes as her friends tried to dislodge her. Then her heart stopped beating and she was still. Forty minutes after that, a rescue team arrived, cut her out of the ice and administered CPR as they helicoptered her to a hospital. At 10:15 p.m., three hours and 55 minutes after her fall, her first heartbeat was recorded. Since then, she has made a nearly full recovery.
Bagenholm was the very definition of clinically dead: Her circulatory and respiratory systems had gone quiet for just over three hours before she was brought back to life.
But what was happening in her body on a cellular level during the hours she went without a heartbeat? Weren't her tissues dying along with her consciousness? If that is so, how could she have recovered? Wouldn't that mean that corpses could also do this?
The answers to these questions start in the cellular level. According to Dr. Honglin Zhou (an assistant professor of emergency medicine at the University of Pennsylvania), as well as many other scientists, that unlike the larger organisms they form, there are clear ways to tell whether an individual human cell is dead.
Every cell has a tight outer membrane that serves to separate its own contents from its surroundings and filter out the molecules that are nonessential to its function or survival. As a cell nears the end of its life, this protective barrier will begin to weaken and, depending on the circumstances of a cell's death, one of three things will happen: It will send an "eat me" signal to a specialized maintenance cell that will then devour and recycle the ailing cell's contents; it will quarantine and consume itself in a kind of programmed altruistic suicide; or it will rupture abruptly and spill its contents into the surrounding tissue, causing severe inflammation and further tissue damage.
In all cases, when the integrity of the outer membrane is compromised, a cell's fate is sealed. "When the permeability of the membrane has increased to the point that the cellular contents are leaking out, you have reached a point of no return," Zhou said.
The cells necessary for performing tasks (such as attacking a city) in long-dead corpses would be inoperable. Because of this, a long-dead corpse reanimating itself as well as a real-life Frankenstein's monster is not possible.

Sorry, Frankie.

Then how did this Bagenholm gal survive? Well, as it turns out, it can take some cells quite a long time to die. When human cells are abruptly cut off from the steady supply of oxygen, nutrients and cleaning services that blood flow provides them, they can hold out in their membranes for a surprisingly long time. In fact, the true survivalists in your body may not die for many days after you've lost circulation, consciousness and most of the other things most people consider integral parts of living. If doctors can get to the patient before these cells have crashed, re-animation is still a possibility.
Unfortunately, the cells that are most sensitive to nutrient and oxygen deprivation are brain cells. Within five to 10 minutes of cardiac arrest, neuronal membranes will begin to rupture and irreparable brain damage will ensue (remember this information for part 2). To make revival efforts even more difficult, a surefire way to kill a cell that has been cut off from oxygen and nutrients for an extended period of time, is to give it oxygen and nutrients. In a phenomenon called reperfusion injury, blood-starved cells that are abruptly reintroduced to a nutrient supply will quickly self-destruct.
The exact mechanisms of this process are still not well-understood, but Zhou speculates that when cells lose blood supply they may go into a kind of metabolic hibernation, with the goal of self-preservation. When the cells are roused from this state by an onslaught of oxygen and panicking white blood cells in an environment where toxins have accumulated, they are overwhelmed with inflammatory signals and they respond with self-immolation.
Though scientists don't fully understand the causes of reperfusion injury, they know from experience that one thing that stifles its onset is to lower a patient's body temperature. This is why Bagenholm, who arrived at the hospital with an internal body temperature of 56 degrees Fahrenheit (about 13 degrees Celsius), was able to recover and why one of the primary areas of research for the CRS is the application of so-called "therapeutic hypothermia."

Is a zombie apocalypse really possible? What would it be like?

We've all seen TV shows, movies, video games, and books about a devastating apocalyptic scenario in which humans turn into mindless cannibals who's only goal is to devour living people and throw the world into chaos. That's all fictional, though right? There's no such thing as a "zombie virus" is there? Are there any true facts behind a real zombie apocalypse? 
According to Elankumaran Subbiah, a virologist at Virginia Tech, a viral rabies hybrid really could create a zombie apocalypse, but it would have to be genetically engineered, since  mutations occur randomly in nature. “They [viruses] are too different from each other. They cannot share genetic information. Viruses assemble only parts that belong to them, and they don’t mix and match from different families,” said Subbiah. “Sure, I could imagine a scenario where you mix rabies with a flu virus to get airborne transmission, a measles virus to get personality changes, the encephalitis virus to cook your brain with fever and throw in the ebola virus to cause you to bleed from your guts. Combine all these things, and you’ll get something like a zombie virus. But this couldn't all naturally happen at the same time.”
Phew, zombie apocalypse averted... right? Unfortunately, the modern world has this scenario becoming a frightening reality. What if a country or terrorist group were to purposefully genetically engineer a zombie virus as a weapon of mass destruction?
Fortunately, scientific knowledge for creating an artificial virus is not exactly a common specialty, and it took a team led by J. Craig Venter years to make the first major scientific breakthrough. But in August of 2014, researchers from Wageningen UR successfully developed an artificial virus for the first time. The long-term goal is to apply these techniques to biotechnology, medicine, and nanotechnology, but how long will it be until these techniques are weaponized? If that scenario were to ever become reality, the world may wish the zombie apocalypse had been created by nature instead of man.