There have been 20 cases reported now in California.
The family of 2-year-old Lucian Olivera has been battling the mysterious illness for nearly two-years.
They say it all started with a fever and an ear ache and then Lucian lost feeling in his leg.
After months of testing and misdiagnosing, researchers linked it to California polio-like syndrome which is what they're calling the mystery outbreak.
Doctors say the damage to Lucian's legs is permanent, but rehab therapy is helping him to learn to stand and eventually walk with a cane.