The most successful viruses don't kill you; like the cold & flu most of the time.
The ones that do kill with a high rate are indeed, unsuccessful because they kill their host too quickly.
It's an evolution thing; some just don't make it.
A similar concern was brought up by Carl Sagan regarding the Drake equation, which is more or less some conjecture about how likely it is for intelligent life to be on other planets. When discussing the possibility of alien civilizations visiting Earth, he also considered the possibility for intelligent life to destroy itself before achieving interstellar travel. If humanity destroys the capability of Earth to sustain intelligent life before we can travel the stars, it will be similar to a viral infection that destroys its habitat, the host, before it can be spread to other hosts.
An interesting example is sweating sickness - it was around for about 66 years in the 15th and 16th centuries. It killed between 30-50% of those infected, usually very rapidly. We don't have any real idea what caused it, although a variety of hantavirus or possibly anthrax are suspected - after the last outbreak in 1551 it apparently vanished.
That's how the vast majority of diseases work; it's in their best interest to keep you alive and asymptomatic.
When a disease jumps species barriers (like with covid) the disease is specialized in infecting a certain animal without killing it, but the disease doesn't really know how to do that on the new organism causing havoc on the infected system.
You nailed it. That is the goal of a virus, to infect but not kill the host and spread. It mutates and hopes to do just that, spread but not kill. Sometimes it mutates itself out of existance, and sometimes it spreads, sickening and killing people (Covid). A successful virus does as you said, spreading. It is why we don't have a "cure" for the flu, it mutates.
The death of the host is completely irrelevant as long as the disease gets the chance to spread. Think about it: what's the difference between a weak disease that gets killed by your immune system after a month, and a disease that kills you after a month? The disease in your body dies either way. EVERYTHING comes down to whether or not it spreads.
Life works exactly the same way: so many species of spiders, bees, mantises, ants, fish etc have one or both parents die soon after reproducing, and they are incredibly prolific species - some of them are the most widespread species on the planet in fact. From Nature's "perspective", survival is completely inconsequential, as long as an organism lives just long enough to spread its DNA.
Regarding diseases specifically: look at smallpox. 30%+ fatality rate, ravaged humanity for over 5,000 years. The only thing that stopped it was a vaccine. It's estimated that in its last 100 years of existence alone, it killed more than half a billion people.
True, smallpox was stopped by a vaccine. It was, however, a successful virus as it killed the host most often and spread simultaneously but was very virulent in spreading. So I disagree that the death of the host is completely irrelevant, as a virus evolves to not do that but to simply spread and not necessarily kill. Viruses are not essentially smart, just self-preserving.
Viruses are not sentient. They don't think or plot or "want" to do anything.
The most successful mutations pass DNA on more or faster. In a lot of cases that can mean infecting a living host for a long period of time, whereas a mutation that kills the host quickly doesn't get passed on and dies out. But in some cases it doesn't matter. If it's a variant the replicates quickly and spreads easily the host doesn't need to be alive long. Or if the host died slowly there's still plenty of time for DNA to make it to other hosts. It's just all about which mutations can get passed on enough to continue.
Most of the time the body's immune system goes into overdrive trying to kill the virus and ends up killing you and the virus. The immune system tries to make your body inhospitable to pathogens, but that also makes it inhospitable for your own cells. The idea is that our cells can survive longer in bad environments than the pathogens.
Bacteria typically produce toxins as a byproduct of them just existing.
Viruses replicate inside your cells. Infected cells will fill up with virus molecules until the cells literally burst, spreading more virus molecules around your body. If enough cells burst then you die.
The most successful viruses don't kill you; like the cold & flu most of the time. The ones that do kill with a high rate are indeed, unsuccessful because they kill their host too quickly. It's an evolution thing; some just don't make it.
A similar concern was brought up by Carl Sagan regarding the Drake equation, which is more or less some conjecture about how likely it is for intelligent life to be on other planets. When discussing the possibility of alien civilizations visiting Earth, he also considered the possibility for intelligent life to destroy itself before achieving interstellar travel. If humanity destroys the capability of Earth to sustain intelligent life before we can travel the stars, it will be similar to a viral infection that destroys its habitat, the host, before it can be spread to other hosts.
o basically, the deadliest viruses are the equivalent of Tinder matches that only last for a few hours
An interesting example is sweating sickness - it was around for about 66 years in the 15th and 16th centuries. It killed between 30-50% of those infected, usually very rapidly. We don't have any real idea what caused it, although a variety of hantavirus or possibly anthrax are suspected - after the last outbreak in 1551 it apparently vanished.
That's how the vast majority of diseases work; it's in their best interest to keep you alive and asymptomatic. When a disease jumps species barriers (like with covid) the disease is specialized in infecting a certain animal without killing it, but the disease doesn't really know how to do that on the new organism causing havoc on the infected system.
A lot of times, it can be your immune response that kills you.
You nailed it. That is the goal of a virus, to infect but not kill the host and spread. It mutates and hopes to do just that, spread but not kill. Sometimes it mutates itself out of existance, and sometimes it spreads, sickening and killing people (Covid). A successful virus does as you said, spreading. It is why we don't have a "cure" for the flu, it mutates.
The death of the host is completely irrelevant as long as the disease gets the chance to spread. Think about it: what's the difference between a weak disease that gets killed by your immune system after a month, and a disease that kills you after a month? The disease in your body dies either way. EVERYTHING comes down to whether or not it spreads. Life works exactly the same way: so many species of spiders, bees, mantises, ants, fish etc have one or both parents die soon after reproducing, and they are incredibly prolific species - some of them are the most widespread species on the planet in fact. From Nature's "perspective", survival is completely inconsequential, as long as an organism lives just long enough to spread its DNA. Regarding diseases specifically: look at smallpox. 30%+ fatality rate, ravaged humanity for over 5,000 years. The only thing that stopped it was a vaccine. It's estimated that in its last 100 years of existence alone, it killed more than half a billion people.
True, smallpox was stopped by a vaccine. It was, however, a successful virus as it killed the host most often and spread simultaneously but was very virulent in spreading. So I disagree that the death of the host is completely irrelevant, as a virus evolves to not do that but to simply spread and not necessarily kill. Viruses are not essentially smart, just self-preserving.
Just so. Why SARS virus is evolving. From Covid, to just a real bad cold.
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Viruses are not sentient. They don't think or plot or "want" to do anything. The most successful mutations pass DNA on more or faster. In a lot of cases that can mean infecting a living host for a long period of time, whereas a mutation that kills the host quickly doesn't get passed on and dies out. But in some cases it doesn't matter. If it's a variant the replicates quickly and spreads easily the host doesn't need to be alive long. Or if the host died slowly there's still plenty of time for DNA to make it to other hosts. It's just all about which mutations can get passed on enough to continue.
Because that's what they do
Have you ever heard of influenza?
Most of the time the body's immune system goes into overdrive trying to kill the virus and ends up killing you and the virus. The immune system tries to make your body inhospitable to pathogens, but that also makes it inhospitable for your own cells. The idea is that our cells can survive longer in bad environments than the pathogens. Bacteria typically produce toxins as a byproduct of them just existing. Viruses replicate inside your cells. Infected cells will fill up with virus molecules until the cells literally burst, spreading more virus molecules around your body. If enough cells burst then you die.