I'll give the unlearned magician a quick rundown.

Smallpox, the disease that we're fighting here, starts displaying symptoms 1-2 weeks after infection.

At that point, you get a fever as high as 40 °C.

It goes away in a few days, but...

Your whole body is covered in a rash instead, and that rash starts to fester.

Then, a few days later, another high fever. From there, you'll start to recover in about a week...

But about 3 out of 10 people are dead by then.

Not just that, it's so infectious

that it could be a catastrophe in this cramped little village.

Understand?

Thank you for the second-hand explanation.

But yeah, wow. That bad, huh?