Data shows a record number of confirmed Acute Flaccid Myelitis cases were reported in 2018.
The Centers for Disease Control said there were 193 confirmed cases of the polio-like illness reported in 2018 alone.
Four of those cases were in Arizona, according to the CDC.
Health experts are investigating 349 AFM cases nationwide.
Researchers are still trying to determine what causes the paralyzing condition which mainly impacts children.