What would happen if a virus could not be cured or contained?
I would like to know what would happen if a new virus arose which could not be cured and which managed to escape the infected areas (and any quarantine zones). In order to scope this question I'm not interested in how humanity would adapt I want to know about how the infected rates/death tolls over time based on patterns from historical epidemics.
- Let's assume the virus is spread through body fluids (seems common enough)
- No human doctor can treat it
I want to know
- Assuming there was no medical cure would everyone die?
- Or is it likely some people would be naturally immune/recover?
- What would happen once the virus infected everyone? Would the entire population die off? Would it subside (like a predator) then reassert itself when humanity has rebuilt itself?
The answer I'm looking for will look at major outbreaks from the past and extrapolate what would happen if something similar happened today. Just to repeat myself I'm not looking for humanity's response to a global contagion, I'm looking for the patterns the virus would follow.
This post was sourced from https://worldbuilding.stackexchange.com/q/3235. It is licensed under CC BY-SA 3.0.
2 answers
First and foremost, everyone would not be infected, let alone die. Look at Brazil and Peru and the tribes of the Amazon, many of whom still haven't been contacted. Since they have no human contact, they won't get non-airborne diseases from outside. Since you say it is fluid-borne, they won't be affected. This can also be demonstrated by the fact that when new tribes are contacted, two-thirds of them die out within the year (Tribes of the Amazon documentary, BBC Four). This is because they have not had any diseases from outside, so are not immune to them.
It is unlikely to abate then resume. Many viruses have a life of just a few minutes outside the human body; even the more deadly viruses like Ebola and anthrax (though not technically a virus) have a lifetime of a few hours. For example, the Plague did this: killed off a load of people, then died out. Admittedly it was helped in London by the Great Fire in 1666, but in many other places it just died out.
In the end, it's likely that a significant proportion of humanity would be killed; modern communication and travel makes spreading disease much faster than in the past so an epidemic can become more deadly. However, some isolated humans would survive and might be able to make use of the remaining technology and machinery to survive.
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First, the deadliness of a virus can vary widely from mostly harmless (Herpes) to very deadly (Ebola). However, note that even for Ebola, there are people who survive without treatment. Indeed, Ebola cannot be cured; all the treatment does is to try to keep the patient alive for long enough that the body can fight the virus by itself.
An important question is how quickly the virus mutates. Most viruses mutate slowly, and therefore if you survived once (or got vaccinated, if a vaccine can be developed) you're immune to the virus for the rest of your life, or at least for many years. Other viruses, like Influenza or HIV, mutate more frequently, which means that even if you're immunized against one strain, you'll still be unprotected to another strain (this is why Influenza vaccination is repeated every year: It's always a new strain that becomes prevalent).
Note that there's also an evolutionary force on the virus: As soon as it spreads too violently, it will have a harder time to spread further, since all potential hosts are already dead or immunized, and moreover will put the more effort into avoiding the infection, the more deadly it is. Therefore there's a selective pressure on the virus to become less deadly, or less infectious. Probably as long as there's no cure, ultimately an equilibrium would be reached like for measles or mumps in the middle ages, where it is common, but not as common to threaten humanity as a whole.
Of course, as soon as a cure of an effective vaccine is developed, the equilibrium will change to less ill people, if the virus will not be eradicated completely (as happened with smallpox).
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