Demon Pox, also known as astriola, is a disease contracted through sexual relations with demons.
Initially dormant, the infected would, according to Will Herondale, soon turn green and yellow. Swelling will then follow. A shield-shaped rash will then appear on their back, and once the disease spreads, cracks and fissures on the skin will begin to appear. The demon pox would then aggravate and lead to insanity, and in Benedict Lightwood's case, he turned into a giant worm.
Will Herondale was shown to have had an immense interest in demon pox and had always been passionate about proving its existence. When it was proven to be a real disease, Will is ecstatic and made up a song about it.  He later taught the song to his children and grandchildren.
Just how is it acquired?
One must go down to the bad part of town
Until one is very tired.
Demon pox, oh, demon pox
I had it all along—
No, not the pox, you foolish blocks,
I mean this very song—
For I was right, and you were wrong!”
To prove that demon pox warps the brain.
So though 'tis pity, it's not in vain
That the pox-ridden worm was slain:
For to believe in me, you all must deign.”
Known Victims Edit
- Benedict Lightwood - Benedict's condition was severe that he needed the medication supplied to him by Axel Mortmain. This eventually failed and lead to Benedict's death. He then turned into a gigantic worm and went on a rampage around the Lightwood estate, killing Rupert Blackthorn.
- Barbara Pangborn - contracted the pox from her husband, Benedict. She committed suicide out of shame and humiliation after discovering she had contracted the disease from her husband.