Subsequent to the appearance of chapters on North American California (CAL) group virus infections in the first edition of this handbook, ^{37 , 47} several comprehensive reviews were published. The proceedings of the 1982 International Symposium on California Serogroup Viruses included more than 30 summary papers. ⁷ More recent reviews have been presented by LeDuc ³⁴ and Grimstad; ²² important early reviews of the CAL group predating the first edition of this handbook were noted in the latter review. In keeping with the editorial policy of the second edition reference will be made to review articles and other important information summaries as much as possible throughout this chapter.