I have decided on my preferred method of zombie apocalypse. I have chosen super leeches. But I have run into some problems, I'm not entirely sure if such a thing would be possible. I have a few ideas.

These leeches should feed off of blood. Human blood should be preferred, although I would be okay if they also fed off of other animal's blood. Humans should also be their primary host, if not the sole one.

These leeches are a quarter of an inch to a half an inch wide, and of varying lengths. These leeches infest their human host, feeding off their blood. A single worm is extra small and smart, and it infects the brain, controlling the body parts. other worms assist the human host in its movement. Smashing the person's brain, or damaging it enough, would make the host unusable, because the worm would not be able to control the body.

To adress Wylia's comment, the worms can target pretty much anywhere. But it is a requirement that you can kill the zombie by bashing its head in. Also, I don't know how they reproduce, probably similar to tape/ring/worms or leeches. I always imagined the worm thingies just burrowing into people's skin. Zombification should probably only take about five minutes.

Given these requirements, is a worm/leech such as this possible? If not, how can I make it so and still maintain the stereotypical zombie?

  • $\begingroup$ Just a few things: How do these creatures reproduce? And why do they infect the brain and not, say, the heart? Perhaps certain chemicals produced in the brain, along with blood, help feed the leeches. And it might be helpful to consider in what way(s) and how long the "zombification" process takes to occur. $\endgroup$
    – Wylia
    Mar 13, 2016 at 5:11
  • $\begingroup$ @Wylia I just thought I's keep the idea that bashing in a zombie's brains kills it, instead of targeting the heart. I don't know how they reproduce, probably similar to tape/ring/worms or leeches. I always imagined the worm thingies just burrowing into people's skin. Zombification should probably only take about five minutes. $\endgroup$ Mar 13, 2016 at 5:26
  • $\begingroup$ If you're going to doe vote, at least tell me why. I mean, just give me a reason. Just a little bit's enough. $\endgroup$ Mar 13, 2016 at 23:27
  • $\begingroup$ So, you are going to create Micro-Goua'uld? Anyway, that does remind me of an episode from X-files. That project purity stuff... the black oil alien creatures... sorry, can't recall the episodes name, but there where little black worm like creatures that attached themselfes to that part of the brain that creates these hormones that cause anger... wait, it must had been one from the first or second season, where they went to a science ice drill lab. Ah... "Ice", episode 8, season 1. That might be of interest for you. $\endgroup$ Mar 14, 2016 at 9:17
  • $\begingroup$ I got the idea from goma worms in the book series Beyonders by Brandon Mull. Because who doesn't love worms that make zombies? $\endgroup$ Mar 14, 2016 at 13:45

3 Answers 3


I get stuck on your "super smart leech" requirement. Having the leech wired into the brain and running the human by remote control is more Puppet Masters than Zombie.

Instead, just have your leech hiding inside its host's living body, secreting chemicals to induce extreme rage and perhaps ravenous hunger. If you want to chemically lobotomize the host in the process, that is fine; and messing with muscle control (for slow zombies) or adrenaline levels (for fast zombies) could also help you stay true to the myth.

As for keeping the lethality of smashing in the skull, that is just a side effect of keeping the human host alive. As long as the leech is feeding off of its host's living blood, then they are both in trouble when the hosts skull gets destroyed.

  • $\begingroup$ That is definitely better than simply a smart worm. But would it be biologically feasible to have a leech, genetically engineered or otherwise, to have creatures that do these things? (This definitely takes less worms.) $\endgroup$ Mar 13, 2016 at 14:28
  • $\begingroup$ I'm not a geneticist so I cannot speak to our deliberately creating these worms using current science, but there is lots of chemicals which induce rage; pcp for example. In a book, with the proper setting and back story, I think this is a perfectly acceptable way to create zombies. $\endgroup$ Mar 13, 2016 at 22:27

Given the question i would answer like this
Feeding on human blood
The feeding on human blood requirement can be met. The size should also be ok.
They could use animals as a means of transport without infecting the host (or do they?). So humans can stay "primary host" for (zombification by) the leeches. Much like toxoplasma gondii

"...is capable of infecting virtually all warm-blooded animals, but felids ... are the only known definitive hosts in which the parasite can undergo sexual reproduction..."

They could alter the hosts behaviour by secreting enzymes (as leeches do) and a bunch of other stuff (like compounds from an endosymbiotic bacteria?) into the bloodstream. This wouldn't allow a leech to gain full control over a human (probably no leech controlled movements), but it could be able to "adjust" the behaviour in a way supporting it's needs (as Henry Taylor mentioned).
Another way could be secreting superleech salvia containing ingredients triggering a higher hormone output, while another ingredient inhibits the hormons resumption.

As to the stereotypical zombie and his zombification.
The leeches would need to ensure the hosts survival as they feed from blood and as soon as the human is dead blood will become a limited resource and the heart stops beating. Sure one leech won’t need that much blood, but no new blood and a bunch of blood-sucking super leeches will render the host useless (after some time). The leeches would need a way to prevent this but since these are superleeches they may have found a way to kill their host maintaining "basic" functions. Like heartbeat or some other way to let the blood flow.
A zombies mindset doesn’t include a rotten body.
This (more optical) feature/requirement of a zombie could be obtained by the leeches fecies, which (might) include a wide variety of microorganisms feeding on/poisoning living tissue. Nonetheless, this would also render the host useless and can't be in the leeches interest (unless they found a way to maintain a dead body functioning).

And one last to adress reproduction, leeches are hermaphrodites, and since these specific leeches are superleeches, they could either still need a second leech to reproduce or simply fertilize themselves. The eggs could be released into the hosts bloodstream (think of metastases in cancer) and hatch somewhere in the body (superleeches hatch superfast). Some of the leeches might release their eggs into the hosts saliva so every bite would be infectious.

open questions to me

  1. how do they approach their host
  2. how do they infect their host primarily? (infecting one host who infects other humans or tsunamiwaves of leeches swapping over cities)
  3. are those zombies the stereotypical rotten living dead?
    3.1 if they are living dead,
    how do the leeches maintain the dead bodies functions? (this would require them to heavily modify the hosts body)
    3.2 if they are not,
    what makes them to zombies and not just humans behaving strange
  4. do those zombies eat because they are "hungry" or are they on a killing spree as long as the body lasts?
  5. ...


super(zombificating)leeches could be possible but there are still a lot of questions to answer to make this work

and the five minute zombification requirement, superleeches have to be superfast (with whatever they do), otherwise this won’t work

imho leeches as hosts for a zombificating bacteria or virus would make more sense.
nonetheless i like dem little leeches....i thought there were five of 'em not just one..grahhh

  • $\begingroup$ I like your solunions, but would it be possible to have a creature like I described? $\endgroup$ Mar 13, 2016 at 23:27
  • $\begingroup$ @XandarTheZenon edited this in a way to suit your question $\endgroup$
    – chris
    Mar 14, 2016 at 16:52

There are parasites known to alter the behavior of creatures (for example fungus that makes ants climb, bacteria that make mice less scared of cats, etc) so that side of it is certainly theoretically possible. There are substances (alcohol for example) that have drastic effects on human cognitive functions so again that aspect is plausible even if we don't know of anything that does exactly what you are looking for there is no reason it could not exist.

The creature burrowing through to the brain is even sort of plausible, for example the African dragon worm which is a pretty horrific little beast. In fact that would be a better starting point than your leaches since it already gets inside people and burrows around.

Physical damage from the burrowing combined with release of chemicals could explain the "zombification". The life cycle of the creature would probably also involve it extending egg layers through into the mouth of the victim so that when they bite people it injects eggs into them. The real reason to make them hungry is so they bite people.

The main weakness though isn't the creatures themselves. It's the fact that humans are smart. We'll find them, we'll work them out, and we'll develop the means to stop them spreading.


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