One of my local friends (coastal San Diego) who is young and fit and a mountain biker, got valley fever a few years ago and nearly died. He looked like a ghost of himself for a long time. It is an illness to be taken seriously.
The US Centers for Disease Control and Prevention has a very informative webpage,
link, which includes "Print-N-Go Factsheets" for California and for the Southwest. These fact sheets include info on statistics (number of cases).