I Imagine A Few Other Humans Got Bit And Turned Into Little Baby Men - Tumblr Posts
Little Baby Man Disease
Based on this post.
TLDR at the bottom.
So, Danny ends up turning into Little Baby Man(TM). Except it turns out that becoming this incredibly small and feral version of his ghost form is actually because of what amounts to Ghost Rabies.
Dani/Ellie ends up finding Little Baby Danny and brings him to the rest of Team Phantom. Only, once she's done explaining how she found him, he bites her, and she turns into Little Baby Ellie.
As Team Phantom is freaking out, another ghost attacks, only for the two feral Phantoms to immediately bite them, causing them to also turn into a Little Baby Man/Woman version of themselves.
The Team believes for a bit that it just affects Ghosts and do their best to keep the steadily growing number of Little Baby Men from going out of control while they try to figure out a cure. Only Sam and Tucker get bitten. Cue the two turning into Little Baby Men (Tucker looks like a Pharaoh and Sam looks like when Overgrowth controlled her). It turns out that Ghost Rabies can also affect people who are Ecto-contaminated.
Cue Jazz having to avoid an army of feral ghosts in order to get a message to Frostbite so he and the rest of the Far Frozen can work on a cure. She manages to get a message out before eventually falling victim to the disease as well.
Do they eventually make a cure? Yes, but not without a lot of chaos in both the Zone and Amity Park as the Little Baby Man Army grows everyday.
TL:DR: Little Baby Man is born from Ghost Rabies. Ghosts and Ecto-contaminated people turn into a feral army.