I was on my horse and I seen an orc mining a clay deposit. I went over to him and he wanted to sell some skooma and stuff, so I chose the intimidate option and we started fighting. After about 10 hits I saw a disease effect. He 'DID NOT' use a potion. I know this because I checked his inventory before killing him and after killing him. I was using a dragonbone greatsword.
I never knew this could happen.

Did your weapon have an Absorb or Damage enchant?

It is unenchanted.

Obviously he has an allergic reaction to dragon bone.

THIS.

Allergies don't cause diseases.

It's not like you clean your sword anyway.

You just go around sticking it into everything.

Wow you really do get the weirdest bugs don't you?! I wish I can give npc's diseases in skyrim. I can do that in real life though......

This begs the question of user error...though I wouldn't be surprised if something like this happened. Considering that previous games have had spells like "weakness to disease," I wouldn't be surprised if Bethesda had at least thought about putting something like that in. Thing is, there's nothing in the Wiki about it and nobody (that I have noticed) has reported this before (and I know I certainly haven't experienced it). This makes me believe that this was just a bizarre glitch. Likely, considering that dragon-bone weapons are a relatively new addition to the game.

This poor girl got an STD from me licking her eyeball.

Were there any animals around? Animals can transmit diseases to npcs and even other animals/creatures with their melee attacks.

Nothing was nearby.

You really need to clean your sword. You cant go around infecting ppl with diseases... You'll be responsible for an epidemic

Blame Peryite.

That's a cool idea for a Daedric artifact of Peryite for future TES games. A weapon that inflicts random diseases. Could be interesting. Fits with his sphere and all that.

Brilliant.

Peryite's Greatsword of the Plague

He took more than 10 hits with a dragonbone greatsword? All the skooma dealers I come across are poorly equipped, I can't see them taking that much punishment. Then again, I never fight them.

Skooma dealers can't feel that they are about to die.. they just keep fighting. Too much drugs in their system

That feel when you'll never have a corprus tainted sword.

I have a request:

Could you continue to go around sticking your sword into a large number of people to see if they get any diseases? It's certainly worth a thrust of effort.

This might be reproducible.

If Guards attempt arrest claim it's in the name of science.

You sure you checked his stock closely?

They usually quaff a Sleeping Tree Sap (they normally have two) and was probably going to before you killed him. The visual effect probably showed up but the potion wasn't consumed. At least, that's my guess.

He prolly drank one of his sleeping tree sap potions.

Possibly he had the disease beforehand and you just didn't notice?

I like this. I was always angry that one couldn't vanillaly acquire the vomit shout. Don't question my adverb usage.