Girl Genius XXV: It needs work! BUT THE CONCEPT IS SOUND!

[Scarlet Knight]

...

Even if we assume sparks are only 0.1% of the human population and that the constant war and instability has kept the human population down to only half a billion (both numbers I've pulled out of thin air, but they seem reasonable minima), Othar would have to kill 500,000 people in the ~40 years he has left before old age reaches him (assuming that nothing kills him off first in his incredibly dangerous dual professions of hero and spark-killer). That's 12,500 sparks a year, or a little over 34 per day...

Well, he IS a spark-killing spark. I don't think we've ever seen Othar in the "madness place", have we? If he comes up with an fast spreading fatal spark virus, a pandemic may do it in over a year or two & his work may continue after his death.