Diagnostic utility of PCR in detection of clinical cases and carriers of leprosy: A cross sectional study at a tertiary care teaching hospital in central India

Purpose: Since ancient era leprosy is existing across the world. India, Indonesia and Brazil still harbour major proportion of global cases. Child leprosy and Grade II disability indicate delayed diagnosis and persistence of transmission in community. So, this study was conducted with aim to evaluate the diagnostic efficacy of PCR in comparison to SSS (Slit Skin Smear) microscopy for detection of leprosy in early stages in both cases and carriers (contacts). Methods: A cross sectional observational study was conducted on 100 subjects including 50 clinically diagnosed new cases of leprosy and their 50 contacts. Each group was subjected to SSS (Slit Skin Smear) microscopy and PCR using RLEP gene as target. Results: The overall male: female ratio was 2.44. The Slit Skin smear (SSS) microscopy positivity was 34% (n = 17/ 50) among cases while it was 0% (n = 0/50) among contacts. The overall positivity for PCR was 42% (n = 42/ 100) being 66% (n = 33/50) in cases and 18% (n = 9/50) in contacts. About 30% (n = 25/83) of all the microscopically negative subjects were found to be positive by PCR. Conclusions: PCR was found to be a better diagnostic tool both among cases and their contacts. It should be used for screening contacts for early diagnosis and treatment and thus preventing transmission in community. Key message: To diagnose case and contacts of leprosy in early stages even in very low bacterial density using PCR.