Kyle Harper

How do I get from one host to the next?

And how do I evade my host's immunity, which our immune systems are incredible, for long enough to multiply?

And so most pathogens, you know, this is clunky.

There's not like a perfect equilibrium, but they have to like explore the space where there are these various constraints.

And

And they find all sorts of weird ways around it.

And evolution is really, really good and really, really creative unfortunately for us.

And just like the tricks that they find to like hide inside your immune system or to like fake it out are really, really wild.

But –

So one of the – I think there's two reasons why plague is so weird and like we don't completely understand why plague is so weird.

But I think there's two basic reasons.

One is that it's vector-borne, which means that it's transmitted through another organism that is the intermediate.

Yeah.

Arthropod or insect vectors are really annoyingly helpful to certain pathogens.

And most – there's actually a relatively small number of diseases that are transmitted through a vector like this.

But they tend to be really, really nasty like malaria, typhus.

And they can kind of get away with it because even if like you're dying –

You know, a mosquito can come and bite you and transmit malaria to me.

Plague is a vector-borne disease, and it's very, very well adapted to transmit, particularly by fleas, but we think also maybe by lice and other biting organisms.

But really by fleas, it's really, really good at transmitting by fleas.