Evaluation of Real Time PCR Detection of the 47 kDa Gene for Reliable Diagnosis of Pediatric Scrub Typhus

Abstract

Objective: Diagnosis of scrub typhus is difficult, because of its non-specific clinical features and a lack of reliable serological assays. This study assessed real time PCR detection of the 47 kDa gene along with routine IgM ELISA for confirmatory diagnosis of scrub typhus. Methods: This observational study was conducted between March 2021 and February 2023. Real time PCR detection of the 47 kDa gene was used as a diagnostic assay. Confirmed scrub typhus cases were defined by IgM ELISA and/or real time PCR positivity. Results: A total of 105 children (0–18 years of age) were enrolled, 30 (28.57%) of whom were confirmed to have scrub typhus, according to IgM ELISA and/or real time PCR positivity. The clinical symptoms of scrub typhus positive children included fever, diarrhea, abdominal pain, breathing difficulties, lymphadenopathy, rash, headache, edema, seizure, and poor intake. Good statistical correlations were observed among real time scrub positivity, high grade fever of 8.2 days’ duration, the presence of eschar and thrombocytopenia. Non-specific respiratory symptoms; cough, and cold were more severe in patients with scrub typhus. The real time PCR test showed good specificity in discriminating scrub typhus from enteric fever, a common pediatric disease. Conclusion: Detection of the 47 kDa gene with real time PCR has good sensitivity and specificity. The number of days between fever onset and sampling, as well as the administration of antibiotics before sampling, influence the performance of real-time PCR.