Molecular detection of Mycobacterium leprae using RLEP-PCR in post elimination era of leprosy

Leprosy is considered as a contagious disease and is still a health problem in several countries including India. Diagnosis of leprosy is based either on clinical findings or on acid fast bacilli staining. Due to low sensitivity of acid fast bacilli staining most of the leprosy cases were remained undetected. The present study aims to assess the efficacy of RLEP-PCR in the field condition where majority of the patients are acid fast bacilli negative and have early disease. A total of 80 suspected leprosy cases were recruited. Slit skin smear samples were taken for microscopy and molecular experimentation. DNA was extracted and RLEP-PCR was executed for all the 80 samples. To establish the statistical correlation χ² test and Fisher's exact test were made. To elucidate the sensitivity of the test Receiver Operating Characteristic (ROC) was drawn. These 80 leprosy patients comprised of 38 paucibacillary and 42 multibacillary leprosy cases. Of 80 leprosy patients 18 (22.5%) were AFB positive while 53 (66.25%) leprosy cases were RLEP-PCR positive. The results of test of significance (P=0.0001) and Cohen's kappa coefficient (κ) (0.614) indicated that the RLEP-PCR is a better diagnostic tool over AFB microscopy in case detection of leprosy. From the findings we concluded that RLEP-PCR could be used for the definitive detection of leprosy cases in accordance with the clinical findings in the field condition in the post elimination era of leprosy.