The Department of Health says the child is from Sierra County and is the first confirmed case of measles since December 2014.
There have been measles outbreaks in 23 states.
The Centers for Disease Control and Prevention says it has confirmed more than 830 measles cases from Jan to May 10, the greatest number reported since 1994.
Measles was declared eliminated in 2000.
The infection is highly contagious and can be especially dangerous for young children.