Illnesses caused by bacteria can be held at bay by antibiotics, and some viruses can be fought with anti-viral medicine. However, I'd like to create a disease for use as a bioweapon that cannot be stopped.

Here are some things I'd like the disease to do:

  • Be transferrable through fluids
  • Be harmful only to humans
  • Cause death within 48 hours
  • Be untreatable
  • Be able to discreetly enter the body - the terrorists that use it don't want to simply stab someone with a needle and inject in the bacteria/virus
  • Be highly contagious, to the point where mild contact between humans will spread it

Is it possible to create a strain of bacteria or a virus that will create a disease that cannot be treated, cured, or even mildly inhibited by medicine?

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    $\begingroup$ A potential problem with your question is that it kills so quickly, which makes it self limiting. You are infected. The incubation window is really short. You start to feel bad, and a hours later you die. There would be a massive number of fatalities in the first 48 hours, more in the second 48 as people figure out what is going on. Everyone panics and stays home. Within a week everyone who had it is dead, and everyone else is self quarantining until officials get a handle on it. The closest to this was the Bubonic Plague, and that wouldn't be as bad if it happened now because of antibiotics. $\endgroup$
    – AndyD273
    Aug 3, 2015 at 16:24
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    $\begingroup$ This question seems to be the inverse of this question about the credibility of a global pandemic. worldbuilding.stackexchange.com/questions/19945/… $\endgroup$
    – Green
    Aug 3, 2015 at 16:51
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    $\begingroup$ With what tech level? If you want it to be highly resistant to treatment I'd say you best bet would be some kind of modified HIV but airborne and engineered to kill more quickly along with selecting the strains most resistant to modern anti-retrovirals, I'd guess we're still 10 years from a full HIV cure. If you want it to spread really well you'd want it to take a lot longer than 48 hours from infection. If you need the 48 hour window for drama you could have a long period when people can spread it and then a 48 hour window from developing symptoms till death. $\endgroup$
    – Murphy
    Aug 3, 2015 at 17:20
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    $\begingroup$ If you could, please don't. $\endgroup$
    – PyRulez
    Aug 3, 2015 at 20:31
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    $\begingroup$ Paranoid schizophrenia is a symptom, not an infection disease. $\endgroup$
    – jawo
    Aug 4, 2015 at 7:17

6 Answers 6


Basic Mechanism for Incurability: Biofilms

A significant problem in hospitals is how to combat bacteria the form biofilms. These biofilms provide effective protection against a great many decontamination techniques both inside and outside the body. Let's build a disease around that mechanism.

Metabolic Characteristics

The pathogen's metabolic pathways closely resemble those of a normal human cell.

Detection Prevention

Since the host immune system uses receptors on foreign bacteria to identify threats, our pathogen has considerable ability to mimic the host's receptor. (The pathogen mimics the extra-cellular receptors that the host uses to distinguish between self and not-self.) Since the immune system recognizes the pathogen as "friendly", it is not attacked. Theoretically, it would only take a very small amount of the pathogen to induce death in the host.

Spread within Host

Form plaques/biofilms in capillary blood vessels that chock off blood supply to periphery areas. Once blocked off, the bacteria goes into anaerobic mode and starts pumping out a nasty toxin similar to botulinum toxin and more plaque to coat the infected area. The toxin kills off the surrounding tissue then uses the dead tissue as raw material for building a plaque wall. Hiding behind the plaque prevents clean up by the immune system or the lymphatic system.

Bacteria that haven't lodged anywhere continue to reproduce as quickly as they can. As plaques build up in major arteries and veins, the body will start to experience overall decreased functionality. In some/many cases, plaques that form in the heart will duplicate symptoms of Atherosclerosis, though a thousand times faster.


  • Difficulty breathing
  • Irregular heartbeat
  • Black pustules in the extremities.
  • Loss of cognitive ability
  • Severe organ pain
  • Black phlegm in coughing
  • Extreme fatigue
  • Severe itching around pustules
  • Irritation to the lung lining causing severe coughing

Spread between Hosts

Given the pathogen's ability to create strong biofilms in all environments, they may be able to last for long periods outside a host. Strong coughing by the victim will spread the pathogen through the air and depositing it on all manner of surfaces. Once the pathogen lands, it forms a biofilm sufficient to preclude destruction by bleach or any other strong chemical sanitizers. This ability makes sterilization incredibly difficult and allows the bacteria to popup again at a later time to reinfect a host.

Being airborne dramatically increases the pathogen's ability to spread itself. A good cough or two by an infected person in a large, busy international airport such as JFK, Paris, Tokyo, or Heathrow would spread the pathogen across the globe in short order.

Also, under certain atmospheric conditions the pathogen will form into spores and pop off the colony to float around and infect someone else. Consider how hard it is to contain a mildew or mold invasion. That's exactly how hard it is to clean up this pathogen.

Defeated Decontamination Mechanisms

Targeted viral infections - Won't work because you'd kill the host along with the pathogen.

Heat - In the food safety business, it's well known that you can't kill the spores that become bacteria. So even though a food may be sterilized after cooking at food safe temps, if the food is then left at room temperature then it will rapidly become contaminated again. Getting heat high enough to kill the spores usually means making the host into charcoal too.

UV - Biofilms take the brunt of this kind of ionizing damage. UV filters don't work against bacteria encased in UV blocking material.

Chemicals - Hospitals currently fight biofilms that evade such strong oxidizers as bleach. This pathogen has a similar biofilm capability.

Impossible to stop

By mimicking a host's receptors it forms a very difficult to hit target for the immune system. Any drugs that boost immune system function will not help here. By mimicking a host's metabolic pathways, any drug that targets them will also target the same pathways in the host, leading to death.

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    $\begingroup$ This one's pretty good. My only problem with the "impossible to stop" is that it burns to fast. The death toll would be huge in the first 3 days, and after that human contact would basically stop. If people went outside they'd do it gloved and masked. One reason the black death spread like it did was because people didn't know what was causing it, and fled the cities as far as they could go, taking the disease with them. Modern day, every news station would be telling everyone to stay inside, and the national guard would be out with blockades to stop anyone from traveling. No new hosts. $\endgroup$
    – AndyD273
    Aug 3, 2015 at 17:51
  • $\begingroup$ @AndyD273, I've noticed the same thing about the spread where if it "burns" too fast then it dies out. The inclusion of strong biofilm colonies outside the host was my way of getting around this. Maybe I should have them develop spores and become airborne afterwards. $\endgroup$
    – Green
    Aug 3, 2015 at 17:54
  • $\begingroup$ I like the biofilms. Hadn't considered it, and it might be enough to have pockets of infected material around to spread the disease, keep it going over the 10 years. You'd almost have to have it go in spurts (like the flu) or humanity would be extinct long before the 10 year mark. $\endgroup$
    – AndyD273
    Aug 3, 2015 at 18:00
  • $\begingroup$ Am I the only one slightly worried that any internet rando could read this and kill us all? $\endgroup$ Feb 23, 2019 at 5:04

Green gave me an idea, and I'm adapting this from a pretty good book I read recently...

Instead of bacteria or virus, I propose a fungus. Specifically, Ophiocordyceps unilateralis, engineered to work on humans instead of ants. Unlike the book, the fungus would work similar to how it works on ants, and not turn people in to zombies.

Once infected, Ophiocordyceps takes over the hosts brain, giving them an overwhelming compulsion to climb to the highest point they can find, then sit down and die. The fungus would then sprout, releasing spores to infect more people.

The fungus takes over it's victims by mimicking their own bodies chemistry, so it's impossible to block. Wind would distribute the spores over great distances, and then be breathed in, or could grow through the skin like it does with ants.

The spores can stay dormant for a long time, waiting for a host to come along, and it wouldn't work on animals because of differing brain chemistry.

If someone had walked through a cloud of spores, their skin would be covered with them, and so skin to skin transmission would be possible. Likewise, some spores would be shaken loose, attaching to other surfaces.

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    $\begingroup$ Ewww. . . but cool idea. $\endgroup$
    – HDE 226868
    Aug 3, 2015 at 18:21
  • $\begingroup$ @HDE226868 Ophiocordyceps would be a scary thing, but it's not much more Ewww than what ebola or the plague does to a person. Less liquefied internal organs to mop off the ceiling, walls, and floor... $\endgroup$
    – AndyD273
    Aug 3, 2015 at 19:00
  • $\begingroup$ This is basically the premise of the plague in The Last of Us. $\endgroup$ Aug 3, 2015 at 19:30
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    $\begingroup$ The timescale might be an issue here. How long does the fungus take to work? $\endgroup$
    – Tim B
    Aug 3, 2015 at 19:50
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    $\begingroup$ @TimB Great question. In the book it started as soon as it hit the blood stream, and took about 4 hours to take over the host. This is all guess work since it currently only targets ants. Also in the book the fungus was very slow to mature (to give a reason why they became zombies.) These would mature and grow fruiting bodies very quickly. So say they bore in through your pores, start pumping chemicals into your blood to start the compulsion, and start extracting nutrients to grow. after a day they are sprouting and growing the spores, and the host is dying from the buildup of toxins. $\endgroup$
    – AndyD273
    Aug 3, 2015 at 20:12

One type of infectious disease that is completely incurable is prions. The word prion comes from the words protein and infection. Proteins are large molecules composed of strings of smaller amino acid molecules. These strings of amino acids fold into specific configurations that then perform a role in the cell. A prion is a protein that has misfolded for some reason and has taken on a new form. What makes the prion a disease is that this new form is capable of causing other proteins of the same type to also misfold and take on this new configuration. Thus the prion is essentially able to reproduce itself by converting the normal, properly-folded, and functioning protein into the prion form. This can cause a number of problems for the infected host. First, the protein is misfolded and therefore no longer performing the action it is responsible for in the cell, and second the prion form gradually builds up and accumulates into plaques.

Prions are responsible for many diseases in humans and other animals and are collectively known as transmissable spongiform encephalopathies. This is because all known prion diseases kill their hosts quite slowly. They mostly affect the brain where the prion builds up over months or years and results in the death of the neural tissue. This doesn't necessarily have to be the case though. A prion capable of converting normal proteins into more prions more efficiently could theoretically spread through the body incredibly rapidly and cause sudden death.

Prion diseases are entirely untreatable. Hypothetically a vaccine of some sort could be devised, but there are no extant treatments. All it would take to be infected would be the inhalation or ingestion of a single prion molecule. The infectivity would be very high if the prion protein was found in blood or mucus or other bodily fluids, both because the prion would begin to replicate immediately upon contact and because any coughing sneezing or hemorrhaging would release it. Potentially it could even replicate outside a host body. Prions are also extremely hard to kill. To render them ineffective you have to denature the protein, getting it to unfold from its infectious form. This requires both extreme heat and some potent chemicals making proper sterilization incredibly hard. Even a long run through an autoclave is considered insufficient. A prion could still be infectious long after its host died. The cooked meat of an animal that had eaten a prion infected corpse could be infectious even if the prion doesn't effect that creature. The prion would be species specific if the infectious protein were sufficiently divergent from its homologs in other animals.

  • $\begingroup$ I was thinking about answering prions too when I read the question, but you got here almost one year before I did. Have my upvote. $\endgroup$ Jun 22, 2016 at 16:49

Old solutions aren't fun

It was already discussed in the question

Is non-manmade pandemic a realistic threat to modern first world?

that bacteria are quite limited due to antibiotics. They could be made resistant, but that kind of a pain to organise, and maybe stronger antibiotics could be developed to counter.

Viruses are somewhat limited, as once one of more people managed to survive it, a vaccine can be made. Recently there was news of a vaccine for Ebola being tested. HIV was one of the worst due to its propensity to metamorphose. But even that one seems to be receding against new treatments.

All that make it frustrating for your wanabe terrorists. Plus, the trend of viruses to be either very infectious OR very lethal makes it kind of hard.


No, probably, if you allow a bit of time for the science to evolve... Nano-robots is already an emerging technology. For example, some will be aiming to kill cancer cells.

Giving it a bit more time, bio-technologies, should allow to build your nano-robots from biologic materials. And you "program" them to aim at destroying vital organs: like liver. Much like computer viruses, your robots should try to convert the internal body parts to reproduce themselves. They should be designed to circulate in body fluids. If the reproduction rate is well adjusted, you could have an easily infectious disease. Depending on the tuning of your robots, you can limit to certain organs, in order to limit the spread to other animals.

There is of course, the limit of treatment. Once they have been identified, some means will be deployed to fight them. Probably inhibitors, or defensive nano-robots.

But again, experience in computer viruses tell you that the best is to try to simulate an evolution. That the robots appear to change, while keeping the same functions. You take the risk of an evolution which could spread to other animals, but you gain a safety against counter measures.

  • $\begingroup$ Very similar to this: Cowboy Bebop: The Movie. The virus is a biological nano machine which starts off disguised as a lymphocyte. $\endgroup$
    – AndyD273
    Aug 3, 2015 at 20:17

A disease like this appears in the last two books of the Time Riders series by Alex Scarrow, although I forget its name.

Despite killing its host in mere minutes (by liquifying the flesh) it doesn't self limit because as soon as it reaches a host it begins releasing spores (I think this would make it a fungus). It also continues to use resources from the host long after they are dead.

The horrifying way in which it kills it victims causes widespread panic, so qauruntines are largely inneffective.

Because it is so infectious and kills so quickly, it is not safe to seek (and there is no time for) treatment, and researching or developing a cure becomes impossible.


You need the disease to take time, maybe make it kill in a week so it has time before it gets noticed. And the symptoms shouldn't be noticeable. You need something that can be linked to different diseases, or the government will make a vaccine sooner. And you shouldn't do through fluids it should be airborne.


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