Yes, some California ticks carry Lyme Disease. If you want to be scared, read the blog of Kathryn Ely, who had to give up her plans for a 2011 thru hike--and just about everything else--after contracting LD last spring in SoCal. http://www.lemminlyme.blogspot.com/ She'll be at ADZPCTKO to educate hikers about LD.