This volume contains the proceedings of the 5th International Conference on Rickettsiae and Rickettsial Diseases, in which an effort is made to address and clarify issues from clinical, diagnostic, epidemiologic, and molecular perspectives that have remained unsolved in the past. NOTE: Annals volumes are available for sale as individual books or as a journal. For information on institutional journal subscriptions, please visit www.blackwellpublishing.com/nyas. ACADEMY MEMBERS: Please contact the New York Academy of Sciences directly to place your order (www.nyas.org). Members of the New York Academy of Science receive full-text access to the Annals online and discounts on print volumes. Please visit http://www.nyas.org/MemberCenter/Join.aspx for more information about becoming a member.