Diagnostic tests for Rocky Mountain spotted fever and other rickettsial diseases.

Rickettsial diseases continue to confound physicians because of their usually sporadic occurrence and nonspecific clinical presentation. In past years, diagnosis was confirmed only during convalescence; however, newer, more widely available methods, such as antigen detection and improved in vitro cultivation, have enabled a diagnosis at a time when therapeutic decisions are made. Molecular nucleic acid-based techniques have also expanded the spectrum of etiologic agents and illnesses caused by rickettsiae.