Something I just thought of. I thought of putting in the Coronavirus section. But it really doesn’t relate directly to that. So I put it here.
Could a virus, possibly some day, kill every human being? Every man, woman and child. Gone?
I know strangely even the worst plague always leaves some people behind. And I assume there is a reason for that (please enlighten me:)). But viruses also mutate. So why can’t they mutate to do what I just said?
I know the HIV virus is rather odd, in a way. Before the advent of anti-HIV drugs, it was always fatal. Eventually at least. So why not the above mentioned scenario?
(BTW, this is only hypothetical. I am sure no such thing will ever happen. Or will it…?:))
Probably not. A virus is, in a sense, a math problem. Its lethality prevents it from being spread; a virus that is incredibly deadly, like Ebola, struggles to be spread because dead people are not effective at carrying it. Rabies is similar - it is brutally fatal, but even before they had vaccines for it it didn’t kill everyone because it dispatches any person cor animal who gets it.
I think it is unlikely but possible if all the factors came together in just the right fashion. And it doesn’t always have to be direct, it could affect reproduction or cause sterility. I found this article about a study on a rat species that went extinct, ok I know it’s not all rats but still:
Perhaps theoretically you could have someone weld together the three properties of 1) incredibly contagious; 2) lingers in its host a while, asymptomatic, before causing death, and 3) has rabies-like fatality. Then you could get something that wipes out billions of people. But that might have to be created in a lab.
I read a theory that if the virus kills everyone then how will it survive itself if it needs humans to survive, so it will not give kill entire human race according to this theory
It’s TRUE that a virus that could kill everyone wouldnt be very successful, and a virus spreading through the population would tend to evolve to be less deadly over time because less deadly strains will outcompete deadlier strains. However, evolution is not a directed process, and species over consume their resources and go extinct all the time. That a virus would spread successfully but then wipe out its host and go extinct alongside it may not be in the “best interest” of a virus, but it’s not like theres a viral committee that enforces pro-virus behaviour. If the virus is too deadly for it’s own good, then that’s that.
I think that what you would have to have is something similar to an airborne HIV virus. Something that has a long lag time between time of infection and lethality, but is readily transmissible. So that by the time people start noticing it is a problem, everyone already has it. Even then, there are going to be lost tribes in the amazon that won’t be infected, and likely some people who for whatever reason are genetically immune.
It seems very, very unlikely that a virus that killed everyone else would kill the North Sentinelese. In practice, there would probably be other populations that could isolate themselves, at least in the short term, if they knew there was a virus that was killing everyone: people in places like Tristan da Cunha, for example, although I don’t know whether they could survive in the long term without connection to the outside world.
The deadliest diseases I’m aware of, Ebola and smallpox, and maybe the old bubonic plague, killed at most 50% of their victims. That’s a tremendous amount, but smallpox and bubonic plague (both very contagious, although in different ways) struck before people understood the germ theory of disease and later vaccinations. The biggest problem now with disease spreading is the current anti-science climate.
It’s at least theoretically possible to wipe humanity out but would require extreme amounts of “bad luck”. I think at most the human population could crash without being wiped out. The disease would probably have to be genetically engineered and based on something with a slow mutation rate (such as smallpox), because viruses usually mutate to become less lethal over time. The virus “wants” the victim sick, not dead, because sick victims spread the virus, whereas dead victims do not (people avoid corpses, mosquitoes don’t feed on corpses, etc). Measles is one of the most contagious viruses out there, but I suspect it mutates. Some viruses are able to “hide” their antigens except when they attack a cell, although I believe all such viruses are retroviruses that mutate quickly, so it’s unlikely they would remain 100% lethal.
Genetically engineered to be very lethal, not mutate (so it doesn’t become less lethal) and have a fairly long and symptom-free incubation period would be a start. It would need to “hide” away from the immune system, so perhaps a retrovirus (inserts itself into DNA) that does not spawn antigens on the cell membranes until it’s ready to emerge. However retroviruses mutate at a high rate. They attempt to insert themselves into the “right” part of the DNA and often fail. Replicating cells make mistakes, and this includes the inserted DNA.
Even so, some people would be immune due to “luck”. I haven’t taken a uni-level biology class in a long time, but in my recollection people can generate antibodies against antigens that cannot naturally develop. (This suggests that if aliens visited, their bacteria-equivalents would provoke an immune response, even if said bacteria don’t cause illness. Indeed a fatal allergic response to alien contact could become common, if that ever happens.) Furthermore the DNA regulating the immune system is extremely variable (almost artificially so), so literally anything that has antigens would provoke an immune response unless someone has a compromised immune system. As a result someone, somewhere, would be immune. Descendants would be more resistant.
Unless the virus hits everyone at once, some people would die before others. Doctors would notice the disease, start collecting antibodies (since there’s always some sort of immune response) or culture it in animals that don’t get sick or die and try to use this sort of serum to save people. Even efficient terrorist spreading would not get everyone at once. Also, unless the virus is programmed to come out after exactly X days some people will still get sick before others exposed at exactly the same time.
Some viruses cause cancer (because anything that damages DNA could cause cancer). PPV, which causes cervical cancer, is probably the best known. However, cancer is treatable, or at least most types are. (Retinoblastoma is not treatable and is 100% lethal, but that’s a purely genetic cancer that arises in unborn embryos. For obvious reasons it has trouble spreading.)
You need a virus that “hides” itself from the immune system, does not mutate into something less lethal, is as infectious as the measles and is as deadly as Ebola or smallpox, infects without killing for a long time (so it can be “silently” spread) and somehow emerges at the exact right time (which would require human intervention). Said virus would need to trigger multiple systems (eg cause an allergic overreaction in addition to the usual causes) and would need to somehow bypass the kind of genetic/immune system “luck” some people have. Furthermore doctors and scientists would have to fail to culture antibodies and the disease would have to wipe us out before vaccines could come online. Even the hiding wouldn’t necessarily work because some unluckly immune compromised person would catch the disease and get sick ahead of schedule, revealing the nefarious plot to science. The likelihood of all of these things happening simultaneously is basically nil.
Probably the closest analogue would be European colonization of the New World. In each case the natives were introduced to multiple diseases, none of which were likely more than 50% lethal, but if you survived smallpox, now you have to survive dysentery, and if you survive that now you have to survive bubonic plague, and so forth. This resulted in tremendous population losses but the descendants of these natives still survive.
Edit: I recall reading a plot (in a novel, not real life) where a virus that sterilized the victims was spread. Fortunately the plot was stopped. I believe such a virus would fail to wipe out the population, but would seriously reduce the size of the next generation.
How many people right now are serving on active-duty naval vessels? Assuming they get the word in a reasonable amount of time and isolate themselves while the landlubbers are all dying, that might be enough to restart human civilization, even assuming 99% of the crews are male. The U.S. has, what, 50,000 personnel on its carriers (*Nimitz *and *Wasp *class) right now? How long could they stay at sea if they had to?
Those vessels have to be resupplied. I suppose if they approach the shore they could be supplied by drones. Even a nuclear submarine would need to go up at some point (they are specifically designed to go very long periods between supplies).
Two of my sons are in the Navy atm, and both had their ships put to sea about a month ago. They are currently not allowing any leave, and when they are in port no one is allowed to leave the ship. Neither is on a carrier, though. I know of one infection on one of our carriers and it’s been pretty bad from what I recall. If it does get on a ship, it’s going to potentially spread rapidly.
Not sure how long a ship with zero support could really stay at sea. The trouble would be if they did come in for supplies, or meet up with fleet oilers, there would be potential for spread, and eventually they are going to need to come in. I don’t know that the Navy is still doing the long duration sub patrols they used to…I think the max is maybe 3 months, but my WAG (been a long time for me) is it’s a lot less. A few weeks to a month these days.
I doubt even a 100% fatal virus with all of the ideal aspects (long incubation while people are asymptomatic yet carriers, etc) would kill the population fast enough that ships could be at sea and come back when everyone is dead. I think it would catch everyone with any sort of interaction if it had the right attributes. But it wouldn’t get all the humans, as there as still uncontacted human groups out there, and humans in remote enough locations that they would have a chance to not be infected from the outside.
But would it be possible for a virus to spread without making people ill for a long time? As far as I understand it, viruses multiply by using their hosts cell; only by having massess of viruses produced in a human body is there a significant chance of being spread to others. This would require at least the start of an active infection. In other words, once you become contagious, you are also having a serious infection, which I would suppose will only become worse: why would the virus suddenly stop multiplying, it is not as if it has a consciousness which makes it hide.
So, given the lifecycle of all viruses it seems as if there should be clear symptoms in a reasonably short while. Particularly if it is deadly. If the virus would simply wait it out, that would give the immune system time to catch up.
A large leap in design would generally be necessary. Evolution just tweaks things a little by a little and that, in turn, allows all of the other organisms to also be tweaked little by little to keep the status quo more-or-less as it is.
Consider that the Old and New Worlds were almost completely isolated from one another for thousands of years. Once they met each other again, disease ravaged both regions (particularly in the New World) because a large amount of evolutionary change had occurred in both places without a matching counter-evolution among the humans in the opposite place.
Global transportation, to some extent, protects us from catastrophic disease since we’re all evolving together and pockets can’t fester for thousands of years.
At some point, humanity will be able to engineer diseases. At that point, we’re really all screwed unless a) we have eradicated mental illness from the populace, or b) we have good screening procedures to find disease among the populace within minutes and hours of something being released.
An antibiotic resistant plague would be terrifying. The pneumatic variant kills in 12-18 hours, can use fleas as a reservoir, and spreads through the air between human hosts.
