Bonesaw turned away from her patient.  She spoke to the man, pushing him away.  She might have said something like ‘run’.

The man stumbled five or six steps before his body began to swell.  His right arm bloated up to three or four times the usual size, turning crimson, before it exploded violently, sending shards of bone and a spray of blood into the people nearest him.  He screamed, only for his cries to grow shorter and more frantic, as the rest of him reached that critical mass.  In another ten seconds, the remainder of his body detonated.

...

Behind the child tinker, those in the crowd who had been struck by the blood and flying bone of her first victim were starting to scream as their bodies swelled as well.

Jack frowned.  “Bonesaw.  You know my rule about epidemics.  You have to play fair with the rest of the group.”

“No epidemic!  I promise!”  She said, drawing a little ‘x’ over her heart, “Four or five cycles.  No more.  Each transition is going to have only about half the catalyst of the last, and eventually they’ll be able to fight it off.”

Wildbow, Worm, 12.x (Jack)