Other questions about this are on this meta post.

Context (Updated with new information based on Q1)
In an act of war, an advanced, extraterrestrial species has designed the machina plague - an infectious nanobot pathogen - to wipe out the human race. They will release 10,000 nanobots on January 1st, 2017. Every bot will be located inside one nondescript, human host in Haneda Airport, Tokyo. Release will be at local time.


  • Bots do not effect the host directly after infection in order to reproduce.
  • Health effects occur gradually after required number of bots is reached. Reaching this number may take between 8 and 24 hours after infection. Symptoms reach a sustained peak approx. 30 minutes after the first symptoms occur.
  • Plague is both waterborne and airborne, but bots will only reproduce in human blood
  • Outside of the bloodstream they will survive for up to 48 hours before losing power and shutting down; they may be revived if re-introduced
  • Bots can permeate flesh to reach capillaries
  • Bots reproduce using iron, manganese, lead
  • Hosts infect the bloodstreams of other humans using fangs
  • Hosts may also come in contact with other hosts' skin, or release bots into the air through respiration
  • Only humans can be infected, but other animals may be prey to hosts
  • Bots coordinate with other hosts' bots in proximity; no attempts to infect hosts occur.

Host Changes:

  • Bots lobotomize the host brain; preserve feral instincts and locomotion
  • Bots reroute nutrients inside the body to form fangs, tubes
  • Hosts prey on animals for food
  • Bots repair host if injuries are deadly or life span is exceeded


  • Decapitation separates brain from body, meaning no acquiring food; bots eventually become dormant
  • Stake through the heart stops blood flow; organs die before bots remove stake, causing eventual death
  • Hosts hide from sunlight, which reveals the structures beneath their skin
  • Nanobot communication signals can be detected - identifying a host
  • Signals can be jammed, making hosts attack each other thinking they're more humans
  • Strong EMPS may quarantine large areas as a last resort

The second question in this series:
Assuming the scenario provided in the context is feasible, what negative health effects will the host contract that may inhibit the spread of the plague? Would things such as reduced blood iron, reduced red blood cells, brain alterations, etc. be enough to severely inhibit the hosts, and thus the plague itself?
How would you fix the information in the context so the hosts can be maintained?


4 Answers 4


My biggest concern is what happens to all of the host blood cells that the nanobots destroy in order to reproduce? Does the host body continue to produce new blood cells to replace the ones that were destroyed?

Most importantly: how does the new system handle providing oxygen to the host cells throughout the body?

As far as health risks for the host... unless the nanobots REPLACE the functionality of the blood cells and carry oxygen throughout the body, the body would suffer from hypoxemia to start, and eventually the biological components in the body would start to shut down.


Nanobots should act faster in adults, slower in kids. Kids are unlikely to think of a cure or isolation strategy. They can be disease vector for a long time without being a threat. Adults are more of a risk.

The bots are more intelligent than viruses... they could listen to the speech of a host... as soon as a host sounds like they know anything about virology or tactics, accelerate takeover of that host, or even sacrifice that one host so it doesn't create defense for the rest of the humans.

  • $\begingroup$ This is helpful information but it's more relevant to the first question in the series - it does not address health effects as this question asks. $\endgroup$
    – Zxyrra
    Commented Nov 23, 2016 at 23:34

This is not a virus evolved to reproduce itself as efficiently and quickly as possible, this nanomachinery is designed to spread and infect, meaning it's alien creator would have wanted to avoid the host realising he/she is sick before becoming feral and starts infecting others. Strong symptoms are a giveaway of serious sickness and compels us humans to seek assistance, so the nano machines would probably cause the least amount of damage to the host's metabolism to avoid symptoms more serious than a common cold before they multiply enough to take over the brain. Then, they would numb pain receptors and such to make the feral host keep going as strong as possible for as long as posible.

  • 4
    $\begingroup$ Sometimes I worry about alien invaders posting on these forums to learn how to take us down. $\endgroup$
    – SRM
    Commented Nov 23, 2016 at 5:50
  • 2
    $\begingroup$ "Sorry your supreme alienness, the internet trolls think your plan will not work without a major change, and our scientist predict it will take us 100 years to master the new technology needed." "oh, then I guess we ought to go back home" stackexchage saves the world. $\endgroup$
    – user25818
    Commented Nov 23, 2016 at 17:25


• Bots reproduce using iron, manganese, lead

emphasis mine, and

...but bots will only reproduce in human blood

I would say requiring lead in your blood to reproduce would slow the rate of spread as lead has some pretty well known negative health effects.

While you might see outbreaks in some areas of the world with poorly maintained water systems, or in factory workers who work with lead containing products (paints, batteries, etc.), most healthy people would seem to be poor hosts to this techno-disease.

Of course if people start shooting the un-symptomatic infected, this could have the unintended consequence of providing a source of available lead and might trigger a number of rapid transformations to fully symptomatic carriers.


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