Disease Origin

[Orlong]

So we all know that many diseases/viruses are passed on from one person to another (Tuberculosis, Mono, Herpes, Measles, etc...). My question is, if you can only get a disease from another person, how did the very first person that got the disease get it?

[Simulacrum]

From an animal that would itself not be as severely harmed by the disease, usually.

[Deleted]

From licking a tube station escalate hand rail, then having it mutate into a variation that can easily pass between humans. I am 100% certain that this is how the zombie Apocalypse will start.

Seriously though ?
Disease Origin can come from anything, from stagnant water, to decomposing bodies. it only needs a human carrier to come into contact with it to being to breed.

[Vanyali]

Random mutations in helpful bacteria. Other organisms specifically evolving to reproduce via other organisms (ie, a disease that does well reproducing in birds but lives outside them infecting rats first).

All the symptoms a disease gives is actually your body fighting against it - none are caused by the disease itself so much as the way your body is reacting to where it prefers. So if you have a gut bacteria go rogue all of a sudden you have mass vomiting and diarrhea to get rid of it (which is actually a go-to response by the body to get rid of a lot of things). Something that prefers lungs prompts you to cough to dislodge/ remove it. And so on.

Then, of course, just the reaction of the body to something foreign interfering with bacteria already present, such as one that might feast on gut bacteria that's not harmful... or take it over and change behavior, as a virus would.

[OzoAndIndi]

Mutations, changes that make them transferable to humans.. Figure, in some limited way they're organisms of some sort, and ones that have to evolve very quickly to keep up... like the darn flu, if it didn't keep evolving new strains the flu shots would prob be able to wipe the damn thing out.

[Darsithis]

Disease Origin can come from anything, from stagnant water, to decomposing bodies. it only needs a human carrier to come into contact with it to being to breed.

Doesn't even need that. Many diseases jumped hosts. What was completely innocuous in a cat or dog isn't quite so harmless for us.

[Rukentuts]

So we all know that many diseases/viruses are passed on from one person to another (Tuberculosis, Mono, Herpes, Measles, etc...). My question is, if you can only get a disease from another person, how did the very first person that got the disease get it?

Mutation that jumps species.

[dextersmith]

Diseases can also be caused by dna, genes or cells mutating while duplicating.

[Grimfrost]

All first humans had brown eyes yet now we have all shades of blue, grey and the rarest : green.

[klaps_05]

keep in mind you are in contact with millions of different bacteria every day. the reason you don't get sick or feel any effects is because you have an immune system to fight them off. usually you can have a bacteria affect a wounded animal, use it as a host to mutate and then attack a stronger organism like a human. if the human can't find off the strain he will become the new host where the bacteria will further mutate and that is when you should start worrying.

[belfpala]

From an animal that would itself not be as severely harmed by the disease, usually.

Then the pedantic: so how did that first animal get that disease? yada yada, I'm not going there.

Answer: Microbial/Virus things mutate very quickly.

[Deleted]

From an animal that would itself not be as severely harmed by the disease, usually.

I agree with you.

[Deleted]

Google it

[Masark]

how did the very first person that got the disease get it?

https://en.wikipedia.org/wiki/Zoonosis

[Afrospinach]

So we all know that many diseases/viruses are passed on from one person to another (Tuberculosis, Mono, Herpes, Measles, etc...). My question is, if you can only get a disease from another person, how did the very first person that got the disease get it?

Track down BBC horizon S48E09. It has a lot of eye opening info about virii, they are everywhere, even in a glass of sea water. Most do not react with us in any way but they are constantly evolving as we know - see swine flu or bird flu. Paradoxically they assert life cannot exist without virii, they are one of the most simple forms of "life"(not technically alive)