Most, but not all cases have been linked to several dozen people exposed to the measles at Disneyland.
So far in Arizona there have been seven confirmed measles cases, but there is the potential that a thousand more have been exposed.
Some parents have chosen not to vaccinate their children.
"Probably the biggest reason that people give is religious reasons, real medical exemptions would include kids that have egg allergies... or those who are immuno-compromised such as those who might have leukemia or lymphoma, that are undergoing chemotherapy and their immune system is suppressed," said Dr. Fred Shulski Jr. with MVP Kids Care.
FOX 10 asked Dr. Shulski what he hears as to why they don't want to get their kids vaccinated.
"The biggest thing in the past 12 years is the autism scare, which has totally been rebuked and refuted on thousands of scientific trials," he said.
As to what the doctor suggests to parents who don't want to get their kids vaccinated due to a personal belief, the doctor says.
"I ask them a lot of times, are you going to put your kid in a carseat when you leave the office? And most of them give me a strange look like, I want to keep my child safe. And that's the whole idea with vaccines, why wouldn't you want to do something that is proven to keep your child safe," said Shulski.
Measles is highly contagious officials say it can cause deafness, blindness, or even death.