Sofia Jarvis is four-years-old and lives in Berkeley with her parents and two older brothers. She's the first known patient.
Two years ago, her parents took her to the hospital because she was wheezing. Doctors thought it was asthma. But, it's the mystery illness that has changed her life.
Jarvis twirls like a princess and torments her brothers like a little sister. And, her left arm is limp and paralyzed.
"When we go to the park and you just can see, you know, like a little kid goes to the park and she loves to climb and there's certain things she can't do when she's there," said Sofia's father Jeff Jarvis.
Doctors say Sofia's condition is likely permanent.
"Most of the children we have seen have not recovered use of their arm or leg," said Pediatric Neurologist Keith Van Haren, MD.
A University of California, San Francisco neurologist says two of the children tested positive for Enterovirus-68, a rare virus in the polio family. Samples from the other three local children were not collected or tested soon enough to yield conclusive results.
The average age of the affected children is 12-years-old. Their symptoms set on within days; some of the kids first show signs of a common cold. All of them are unable to move some, or all, of their limbs. Each of them did have the polio vaccine.
Neurologists say paralysis is extremely rare, but they want doctors and parents to be on alert.
"If you think you have a patient with sudden onset of weakness, in one or more limbs, we recommend prompt evaluation with a medical and neurologic specialist," said Van Haren.
Sofia's parents have had two years to adjust and they're looking on the bright side.
"I was with her in the ER, when she was having trouble breathing; I know that we are so lucky that she's here. And I know that many families go through losing a child, so we're so grateful that Sofia's with us today and she's going to do amazing things," said Sofia's mother Jessica Tomei.
Doctors do not want people to panic; they say this is not in any way a widespread outbreak.
The Center for Disease Control is monitoring the situation.