A Sneeze Annihilates a Magical Civilization

"According to modern Earth medical research, a healthy human body carries at least 140,000 types of viruses, and the number of bacteria is even greater.

If such a person were to transmigrate to an unfamiliar magical world, and the bacteria and viruses within them mutated, then suddenly erupted without the person's knowledge, what kind of consequences would that unleash?

I'm not saying this to defend myself!

I just want to prove that the destruction of that magical civilization really wasn't intentional on my part!

It was just an accident, a terrible disaster.

And! Don't call me a 'walking natural disaster'!

That's slander!

It's rumor-mongering!

It's a blatant infringement of my reputation!

Also! All you followers of Talona, get lost!

I have absolutely nothing to do with your goddess!"

Zuo Si (Soth), the multiverse's renowned Planeswalker and the sole chosen one of the Goddess of Poison and Disease (a title he vehemently denies), issues a stern warning to his 'haters' and declares that if necessary, he will resort to extreme measures to defend his reputation.

These measures include, but are not limited to, 'humanitarian annihilation (physical)', forcibly converting them into undead or shadow thralls, extracting their souls to create animated parts for magical constructs, or directly teleporting people to the Nine Hells or the Abyss...