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Diseases kill people by messing up with some mechanism that is necessary for life. This generally means that they have a progression - for respiratory diseases, you will have difficulty breathing for a while; Gastroenteric diseases will give you diarrhea, acidic reflux or malnourishment; Neural diseases will deteriorate your mind or reduce your coordination and so on.

Even heart conditions usually have symptoms that could be described to or by a doctor - you will usually have abnormal blood pressure or chest pains way before having a heart attack.

What I'm looking for is a mechanism that preferrably a virus, but also a bacteria, fungus or other microbe could use that would have no symptoms for weeks to months before causing sudden death. The disease would be infectious and if any symptoms do manifest, it should happen no sooner than a few minutes before death. I am ok with the microbe being detectable with a simple, 20th century blood exam (let's say developed countries, circa the 1990's), but there should be no other way to find out if you have it before perishing to it.

Is such a disease realistic, and if it is, how would it most probably work?


I did not initially mention this, but the mortality and lethality rates do not have to be 100%. It's ok to have people have the disease and never die, but those who do die should be asymptomatic until moments before their death.

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    $\begingroup$ This reported happened during the 1919: some victims just dropped dead in the streets, or at their jobs. $\endgroup$
    – jamesqf
    Nov 29, 2020 at 18:14
  • $\begingroup$ Please clarify whether or not the diagnostic tools are 2020, 1920, or 2120? @jamesqf is correct that people seemed to drop dead during the 1918 Spanish Flu epidemic... but there's a massive difference between 1918 medical and communication tech and today. What we have are the reports from then, but no medical data to back up the idea that they really did just "drop dead" vs. having had fevers, coughs, etc as would be normal. Almost all fatal diseases appear to kill instantly if you can't diagnose the problem. So... what year are we talking about? (And where, while you're at it.) $\endgroup$ Nov 30, 2020 at 1:00
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    $\begingroup$ @jbh let's say developed countries, circa the 90's. I'll add this info to the question. $\endgroup$ Nov 30, 2020 at 2:52

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Quite possible

To achieve this drop dead effect you need two factors: one is insidious progression of the disease and the second is an acute shift against a vital organ.

Insidious progression can be written off as a latent, incubation period of the pathogen with an unspecified threshold. Once reached, the acute shift occurs and well inevitably death follows. As a bonus I would have the virus shed during this entire period. That is true for some Herpes Zoster infections for example. The virus can chronically infect nerves and manifest as the Shingles rash in presence of triggering factors.
So I would suggest that your pathogen infect your target organ during the incubation/latent period to explain the targeted acute shift.

Next, the organ choice should be made. Keep in mind how flashy you want the death sequence to be.
A. I would personally go for a neurogenic shock caused by the virus destroying encephalic and spinal nerves. Some protein, a trigger would set off the bombs the virus was preparing all this time, destroying the entire neural network of the host. I can picture parts of the network being cut sequentially with the host losing control of one body part at a time every few seconds or minutes to make it more graphical.

B. Another equally graphical approach would be to target the heart. In essence, as long as there destruction of myocardium (heart muscle) some things can happen:

  1. Destroy a large enough part and the heart won't pump blood. The person faints, brain hypoxia follows and death.
  2. Destroy part of the neural network of the heart. This would have to destroy a part to create a malignant heart rate that would speed up really fast (200-300+ beats) and then either stop or keep going. The death sequence is similar to 1, aka no blood is pumped.
  3. Destroy many small tissue patches so that a malignant circuit is eventually formed, just like in a myocardial infarction. Make it so that a malignant rhythm develops and we're back to 1.

Another idea for this section is myocardial perforation.

C. Some other organs that would quickly lead to death if destroyed fast enough are:

  1. Kidneys (25% of all blood goes through them every few minutes, bleeding to death is easy)
  2. Lungs (hypoxia, simple and deadly or tension pneumothorax or bilateral pneumothorax, fancier and more graphical due to asphyxiation)
  3. Large vessels: Aorta/Vena Cava (rupture them and death is guaranteed in mere minutes)

A few considerations

From an evolutionary perspective, this seems rather improbable to occur because the pathogen could achieve absolute mortality once triggered, meaning it always kills its hosts. With no hosts, it won't be able to reproduce so its ultimate purpose is lost. No pathogen aims for death, but reproduction.

There should be cases where the pathogen is chronically infecting the host without it triggering a reaction. Also keep in mind that this pathogen would have to be able, to some extent, mimic, trick or suppress the immune system.

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    $\begingroup$ Great answer, but I have to nitpick two things: renal stop kills in days, not minutes (my father had it and survived). Also the goal here is to remain infectious for weeks to months, so there is time for the virus or bacteria to spread. $\endgroup$ Nov 30, 2020 at 3:11
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    $\begingroup$ Thank you! To clarify: I was referring to a form of kidney rupture which is life threatening (but still manageable in cases through surgery). Yes, renal failure can be addressed to an extent as you pointed out, so this obviously doesn’t work. For your goal regarding infection, it is possible for the virus to be transmitted however you like in this answer (is it after all, made up) so you have no limitations. Keep in mind however, that for viruses to actually do something they absolutely must be in a cell. They are defined as obligate intercellular parasites. Hope this explains my thoughts! $\endgroup$
    – Lae
    Nov 30, 2020 at 3:20
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Totally realistic.

All you need is a disease (bacteria or virus or fungus or prion or parasite or... For convenience lets just call them "bugs") that disables a vital life system of its victim.
There are many pathways this can occur:

  • The bug excretes a toxin that weakens arterial walls. No symptoms until an artery ruptures, causing embolism or stroke or aneurysm.
  • The bug proliferates throughout your nervous system, then only once fully established changes its diet and starts eating myelin, promptly paralyzing nerves. Including ones controlling autonomous functions like heatbeat.
  • The bug has a cellwall that structurally resembles your neurotransmitters. As soon as you develop a real immune response to it, your immune system eats your own brain chemicals, shutting it down.

I'm sure there are many ways to kill the victim quickly and without obvious warning. The only real requirement is that the bug starts out being non-damaging, gains a solid foothold in the person, and then change mode to kill. This mode change could be as simple as a chemical trigger that each bug excretes. When the concentration in the blood reaches a suitable level, it triggers the change in the bug.

Such a bug is very believable. The only reason we are not swamped by such things is that it is a counter-evolutionary characteristic for the bug to have. Bugs use sick humans to reproduce and spread. If it kills its victim too quickly, then that bug fails to spread as widely as when it maintains a mobile but sick and infectious victim.

But remove the evolutionary aspect from its development, i.e. make the bug in a lab? Yes, that is very doable and realistic. You just need a lab that is suitably advanced, and an experimenter with a suitable lack of morals & common sense.

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    $\begingroup$ "counter-evolutionary characteristic for the bug to have" - perhaps the health markers that it used in its original host to self-regulate don't exist in humans, but the bug still manages to go on for long enough to wreak significant havoc anyways? (in fact, every self-respecting disease jumps to humans from another host - if it mutated from a different human disease, it would be a strain, not a separate disease). $\endgroup$ Nov 29, 2020 at 8:13
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Rabies is very close to fitting the bill. You have no symptoms for 1-3 months after you catch it, and then you die within 3 days. The virus crosses the blood-brain barrier by traveling through your peripheral nerves to the central nervous system, which is what makes the incubation period so long.

So, the only difference is that it's 3 days from onset of symptoms, not minutes. Is it plausible we could have a strain that makes it minutes? I would guess so, why not? The only problem is that a few minutes is too little to transmit virus to someone, so, either the person has to become infectious while asymptomatic, or human-to-human transmission is not the main mechanism - e. g., you could have an animal host for which the disease behaves differently.

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