Diagnosis of acute typhus infection using the polymerase chain reaction.

The first use of the polymerase chain reaction (PCR) for the diagnosis of an acute rickettsial infection is described. A primer pair derived from the 17-kDa antigen sequence of Rickettsia rickettsii gave specific amplification of a 434-base pair DNA fragment from the genome of Rocky Mountain spotted fever and endemic and epidemic typhus. The assay could detect as few as 30 rickettsiae. Detection of PCR-amplified DNA with a nonradioactive DNA probe confirmed an acute infection with Rickettsia prowazekii.