Real-Time RT-PCR Detection of Rickettsia species -- PanR6/Total Nucleic Acid Assay with High Sensitivity and Specificity

Rickettsial infections are caused by bacteria from the Rickettsia genus which are often spread by biting ticks, fleas, mites or lice. Rickettsia can cause mild to severe illness and Rickettsia species can be found worldwide. Early stage, nonspecific symptoms of infections can make clinical diagnosis difficult. Rickettsial infection symptoms, if present, typically develop within 1 -2 weeks of exposure and include fever, headache, malaise, rash, nausea, and vomiting. Some rickettsial diseases such as Rocky Mountain spotted fever (RMSF), Mediterranean spotted fever, and typhus fever, can be life threatening and even fatal in 20% - 60% of untreated cases. Prompt identification of rickettsioses and treatment are essential. No vaccine is available for preventing rickettsial infections.

CDC scientists have developed a Pan-Rickettsia genus (PanR6) real-time reverse transcriptase PCR (real-time RT PCR) assay targeting both rRNA and rDNA in total nucleic acid (TNA). With high specificity, PanR6 detects 16 Rickettsia species and excludes 15 near neighbors (similar species). Increased sensitivity and accuracy of Rickettsia genus real-time RT PCR detection in clinical samples provides an important step towards early and more effective diagnosis of rickettsial infections. In patient sample testing, the sensitivity of the new PanR6/TNA assay increases diagnostic accuracy by increasing detection sensitivity 100 to 1000 times over current molecular DNA, southern blot, and serological tests which depend upon the specimen collected. A mock clinical specimen panel is being assembled for additional PanR6/TNA assay precision and accuracy validation.