@kritiper I think maybe you don’t understand. Not everyone is going to have that necrotizing bacteria on their skin when they get a paper cut.
Airborne diseases are probably the scariest.
Remember, we are talking about the total destruction of the human race.
If you’re concerned about MRSA and necrotizing bacterias getting in through a break in our skin, only people who get cut and are exposed to that bacteria will die.
A disease that travels in a vector like mosquitoes is usually more of a risk in the tropics.
Diseases like TB, which has mutated and there are very resistant forms of TB now, are only contagious at certain stages, and we can contain reasonably contain (quarantine) it.
Diseases from unhealthy conditions usually are contained to the people who live in that locale.
I’m not saying what you said is impossible, I’m only saying a total wipe out of the human race through a disease is probably improbable. It might get the majority of us, but I don’t think it’s likely to get all of us.