Beyond serology: using molecular methods for the detection of Rickettsia and Orientia in clinical samples

Background Serological assays and conventional PCR used for detecting Rickettsia and Orientia are time-consuming. Given that therapeutic approaches for these infections overlap, early molecular detection significantly enhances timely clinical management. This study evaluates the utility of real-time PCR for the detection of Rickettsia and Orientia compared with ELISA and the Weil–Felix test. Methods A total of 243 patients (92 females and 151 males) were enrolled. The Weil–Felix test and ELISA were performed to detect the spotted fever group, the typhus group and Orientia. Molecular testing included Pan-Rickettsial PCR targeting Pan antigen and real-time PCR for Orientia targeting 47 kDa. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated. Results Real-time PCR exhibited a sensitivity, specificity, PPV, NPV and accuracy of 88.5–95.0%, 83.25–96.0%, 81.91–96.0%, 89.42–95.0% and 85.68–95.0%, respectively. The ELISA showed a sensitivity, specificity, PPV, NPV and accuracy of 81.05–96.0%, 89.45–95.0%, 88–95.0%, 83.18–96.0% and 85.68–95.8%, respectively. The Weil–Felix test demonstrated a sensitivity, specificity, PPV, NPV and accuracy of 20.3–28%, 71–96.6%, 13–57%, 76.3–89% and 65–67%, respectively. Serological tests showed a positivity of 30–75% in convalescent-phase samples, whereas real-time PCR proved superior during the acute phase with a detection rate of 66.7–72.4%. Conclusions This study highlights the utility of real-time PCR as a rapid and effective tool for detecting Rickettsia and Orientia, reducing the turnaround time and simplifying the workflow.