Zombie Pathophysiology
I did some thought and research, trying to figure out how this whole zombie thing might work.
I think the pathogen has two stages.
Stage I: An airborne spore that infects everyone, invading various tissues asymptomatically. As a foreign body, cells transport it to the lysosome, which the pathogen allows, because it's waiting for its activating conditions. Those cues are (1) the change in pH of its surroundings from 4.8 inside the lysosome to 7.2 in the cytoplasm, which indicates that the lysosome has erupted, signifying imminent death of the cell; and (2) the presence of high concentrations of lactate in the cytoplasm, which suggests a state of hypoxemia or anoxia because it is a product of anaerobic glycolysis. These cues are strong indicators that the host is nearly or completely dead.
Stage II: The spore releases its contents, a segment of retroviral RNA and a selection of chemicals that immediately neutralize the digestive enzymes that were released upon eruption of the lysosome. (Some of these substances don't tolerate the presence of oxygen, which is the reason why the airborne stage takes the form of a spore.) The RNA ends up transcribed as DNA inserted into the host's genome. It is a very elegant sequence that hacks the host's genome, mutating it and altering gene expression. Different cells receive different alterations:
- Muscle cells gain the ability to metabolize the lactate that exists in high concentration. Lactate metabolism is relatively inefficient, explaining the host's slow movements and their tendency to enter a dormant phase when no prey is detected.
- Skin, subcutaneous fat, and a portion of blood vessels undergo liquefying necrosis, assisting the escape of the gaseous products of putrefaction. (Bloat inhibits mobility.)
- Most brain cells are digested in order to generate energy reserves; the remainder are retained so that the host has the minimal cognitive ability to pursue and attack prey.
- The hypothalamus goes into overdrive, stimulating insatiable hunger. Further cortical changes specialize this hunger into a drive to consume fresh, raw flesh. Putrefaction leaves the host incapable of swallowing or gastric digestion. The hunger merely works to compel the host to bite its prey.
- The salivary glands gain the ability to synthesize a venom that is lethal to humans.
The cells in tissue remnants left exposed to air produce and release a multitude of stage I pathogens, which start with a hydrophobic layer that helps the particle break free of the moist tissue surrounding it, allowing it to drift on air currents. This layer quickly decomposes in the presence of oxygen.
The bite itself doesn't trigger the host's metamorphosis into the zombie state. It merely envenoms the host, killing it, so the stage I infection can proceed to stage II.
I think the pathogen has two stages.
Stage I: An airborne spore that infects everyone, invading various tissues asymptomatically. As a foreign body, cells transport it to the lysosome, which the pathogen allows, because it's waiting for its activating conditions. Those cues are (1) the change in pH of its surroundings from 4.8 inside the lysosome to 7.2 in the cytoplasm, which indicates that the lysosome has erupted, signifying imminent death of the cell; and (2) the presence of high concentrations of lactate in the cytoplasm, which suggests a state of hypoxemia or anoxia because it is a product of anaerobic glycolysis. These cues are strong indicators that the host is nearly or completely dead.
Stage II: The spore releases its contents, a segment of retroviral RNA and a selection of chemicals that immediately neutralize the digestive enzymes that were released upon eruption of the lysosome. (Some of these substances don't tolerate the presence of oxygen, which is the reason why the airborne stage takes the form of a spore.) The RNA ends up transcribed as DNA inserted into the host's genome. It is a very elegant sequence that hacks the host's genome, mutating it and altering gene expression. Different cells receive different alterations:
- Muscle cells gain the ability to metabolize the lactate that exists in high concentration. Lactate metabolism is relatively inefficient, explaining the host's slow movements and their tendency to enter a dormant phase when no prey is detected.
- Skin, subcutaneous fat, and a portion of blood vessels undergo liquefying necrosis, assisting the escape of the gaseous products of putrefaction. (Bloat inhibits mobility.)
- Most brain cells are digested in order to generate energy reserves; the remainder are retained so that the host has the minimal cognitive ability to pursue and attack prey.
- The hypothalamus goes into overdrive, stimulating insatiable hunger. Further cortical changes specialize this hunger into a drive to consume fresh, raw flesh. Putrefaction leaves the host incapable of swallowing or gastric digestion. The hunger merely works to compel the host to bite its prey.
- The salivary glands gain the ability to synthesize a venom that is lethal to humans.
The cells in tissue remnants left exposed to air produce and release a multitude of stage I pathogens, which start with a hydrophobic layer that helps the particle break free of the moist tissue surrounding it, allowing it to drift on air currents. This layer quickly decomposes in the presence of oxygen.
The bite itself doesn't trigger the host's metamorphosis into the zombie state. It merely envenoms the host, killing it, so the stage I infection can proceed to stage II.
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Comments
I'd like the think that the fact that it was such a big problem was that everyone that has ever died in the last century rose from their graves (Does this mean in countries which practice in cremation like Japan which has a 99% rate of cremation according to Wikipedia actually has a less serious outbreak compared to America, which is where all of the Walking Dead is set... they may actually not really have a problem)
Why? I don't really know, but it hints to a biological reason as anyone that has ever die will reanimate unless the brain is destroyed. Most likely airbone virus or have always existed in the human body and only chose now to act for whatever reason. Good well written theory though, despite the lack of evidence. We can all imagine right?
The thing with dead rising from their graves is, would they have the strength and energy to dig out? This applies especially to coffin burials, which seem to have been the rule over the last century.