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I was wondering about that with the hantavirus, whereby if it's got a higher fatality rate then it's less likely to be easily transmitted. Is that like a gener

I was wondering about that with the hantavirus, whereby if it's got a higher fatality rate then it's less likely to be easily transmitted. Is that like a general rule, or pure bunk? (I'd probably assume the answer 'depends').

RobotToaster 5mo ago
I don't think it's just fatality rate, but also how long it takes to kill you. HIV is a great example of a disease that (untreated) has near 100% mortality rate, but can spread because it takes years to kill you.
- mlinhares 5mo ago
  The real issue with HIV is that you can easily spread it before being symptomatic, so far we haven’t seen hantavirus spreading before folks become symptomatic. The strain that spreads through humans has been active in south America for a while as well and hasn’t really gone anywhere yet.
alamortsubite 5mo ago
Definitely, but the hantavirus incubation period ranges from 1-8 weeks after exposure.
fpaf 5mo ago
From COVID-era discussions (when virologists were briefly the stars of every talk show) I remember one explaining that it was less about fatality rates per se and more about the length of time you could carry the virus around and be nearly asymptomatic while still able to infect others. I understand the jury is still out on whether a virus can be considered "alive" but, like us, it is capable of replicating itself and mutating. In that sense, it benefits from the same evolution strategies as more complex beings: a strain that gets its host very sick very quickly gets a lower chance to spread to a new host and multiply. This creates an evolutionary advantage for strains of that virus that are less aggressive or at least develop the worst symptoms more slowly and more covertly.
- bookofjoe 5mo ago
  >I understand the jury is still out on whether a virus can be considered "alive" I remember way back in med school in the mid-70s our infectious disease professor asking this same question, in a philosophical as much as a mechanistic sense.
  - jijijijij 5mo ago
    Here is the fun thing to think about: If viruses aren't alive, neither are men. Men, too, lack the biological means of reproduction. On the other hand, parthenogenesis may even rarely happen in female humans. https://en.wikipedia.org/wiki/Parthenogenesis https://en.wikipedia.org/wiki/Parthenogenesis
- cogman10 5mo ago
  Yeah. HIV is a good example of this. Without treatment, it is deadly pretty much 100% of the time. However, it takes a long time after the shut down of the immune system before a systematic infection takes over and kills you. That allowed for a deadly disease that's somewhat hard to spread (mostly just through sex) to ultimately go on a rampage.
  - AbstractH24 5mo ago
    I never thought about this. So without concern for the humans with HIV* there an argument to be made that treating symptoms without curing made it spread more? *obviously, this is just hypothetical. It’s important to care about the life of those with HIV. No banish them all to something like a leper-colony. Although it explains the logic for those at the time they existed better than a religious one did.
    - marcosdumay 5mo ago
      > So without concern for the humans with HIV* there an argument to be made that treating symptoms without curing made it spread more? No, because HIV treatment is about killing the virus, and we don't have any that only treats the symptoms. But there is an argument like that for the flu and colds.
jimberlage 5mo ago
Plague, Inc (an iOS game where you control the parameters of a pandemic and try to get a 100% infection rate) will give you a really good feel for the math behind this. The most successful strategy is to make a virus that spreads fast, with few visible symptoms until the late stages of the disease. A deadly virus, early will just cause borders to be locked and the international research community to swarm on a cure.
- leptons 5mo ago
  If AIDS were airborne, I think we'de have a fraction of the billions currently living today. It takes a while for symptoms to show up, there is still no real cure, and drugs to keep it supressed took many years to develop.
rolph 5mo ago
this is a case specific example of a dynamic that may exist dependent on the properties of the pathogen. https://en.wikipedia.org/wiki/Myxomatosis#Australia https://en.wikipedia.org/wiki/Myxomatosis#Australia there are ways to escape the dynamic, such as latency of deleterious symptoms
Jach 5mo ago
"It depends" is usually a safe (if not always helpful) answer. The older idea was that viruses always evolve to be less virulent/deadly, but that didn't match observations. The newer idea is simply that of a virulence-transmission trade-off. But there are various assumptions behind both ideas, and not all viruses follow those assumptions, so.. it depends. A decent review: https://pmc.ncbi.nlm.nih.gov/articles/PMC10066022/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10066022/

RobotToaster 5mo ago

I don't think it's just fatality rate, but also how long it takes to kill you. HIV is a great example of a disease that (untreated) has near 100% mortality rate, but can spread because it takes years to kill you.

mlinhares 5mo ago
The real issue with HIV is that you can easily spread it before being symptomatic, so far we haven’t seen hantavirus spreading before folks become symptomatic. The strain that spreads through humans has been active in south America for a while as well and hasn’t really gone anywhere yet.

alamortsubite 5mo ago

Definitely, but the hantavirus incubation period ranges from 1-8 weeks after exposure.

fpaf 5mo ago

From COVID-era discussions (when virologists were briefly the stars of every talk show) I remember one explaining that it was less about fatality rates per se and more about the length of time you could carry the virus around and be nearly asymptomatic while still able to infect others. I understand the jury is still out on whether a virus can be considered "alive" but, like us, it is capable of replicating itself and mutating. In that sense, it benefits from the same evolution strategies as more complex beings: a strain that gets its host very sick very quickly gets a lower chance to spread to a new host and multiply. This creates an evolutionary advantage for strains of that virus that are less aggressive or at least develop the worst symptoms more slowly and more covertly.

bookofjoe 5mo ago
>I understand the jury is still out on whether a virus can be considered "alive" I remember way back in med school in the mid-70s our infectious disease professor asking this same question, in a philosophical as much as a mechanistic sense.
- jijijijij 5mo ago
  Here is the fun thing to think about: If viruses aren't alive, neither are men. Men, too, lack the biological means of reproduction. On the other hand, parthenogenesis may even rarely happen in female humans. https://en.wikipedia.org/wiki/Parthenogenesis https://en.wikipedia.org/wiki/Parthenogenesis
cogman10 5mo ago
Yeah. HIV is a good example of this. Without treatment, it is deadly pretty much 100% of the time. However, it takes a long time after the shut down of the immune system before a systematic infection takes over and kills you. That allowed for a deadly disease that's somewhat hard to spread (mostly just through sex) to ultimately go on a rampage.
- AbstractH24 5mo ago
  I never thought about this. So without concern for the humans with HIV* there an argument to be made that treating symptoms without curing made it spread more? *obviously, this is just hypothetical. It’s important to care about the life of those with HIV. No banish them all to something like a leper-colony. Although it explains the logic for those at the time they existed better than a religious one did.
  - marcosdumay 5mo ago
    > So without concern for the humans with HIV* there an argument to be made that treating symptoms without curing made it spread more? No, because HIV treatment is about killing the virus, and we don't have any that only treats the symptoms. But there is an argument like that for the flu and colds.

jimberlage 5mo ago

Plague, Inc (an iOS game where you control the parameters of a pandemic and try to get a 100% infection rate) will give you a really good feel for the math behind this. The most successful strategy is to make a virus that spreads fast, with few visible symptoms until the late stages of the disease. A deadly virus, early will just cause borders to be locked and the international research community to swarm on a cure.

leptons 5mo ago
If AIDS were airborne, I think we'de have a fraction of the billions currently living today. It takes a while for symptoms to show up, there is still no real cure, and drugs to keep it supressed took many years to develop.

rolph 5mo ago

this is a case specific example of a dynamic that may exist dependent on the properties of the pathogen. https://en.wikipedia.org/wiki/Myxomatosis#Australia https://en.wikipedia.org/wiki/Myxomatosis#Australia there are ways to escape the dynamic, such as latency of deleterious symptoms

Jach 5mo ago

"It depends" is usually a safe (if not always helpful) answer. The older idea was that viruses always evolve to be less virulent/deadly, but that didn't match observations. The newer idea is simply that of a virulence-transmission trade-off. But there are various assumptions behind both ideas, and not all viruses follow those assumptions, so.. it depends. A decent review: https://pmc.ncbi.nlm.nih.gov/articles/PMC10066022/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10066022/