Cutaneous leishmaniasis in Bikaner, India: Clinicoepidemiological profile; parasite identification using conventional, molecular methods and CL Detect™ rapid test, a new Food and Drug Administration-approved test

BACKGROUND AND OBJECTIVE: Cutaneous Leishmaniasis (CL) is a dermal manifestation caused by various species of Leishmania. This is the most common Leishmanial syndrome seen worldwide and is emerging as and threatens to become an uncontrollable disease. The present study was planned to understand the current epidemiology of CL in the conventionally endemic area of Bikaner, Rajasthan. Species characterization was also done. MATERIAL AND METHODS: The diagnostic modalities used in the study were microscopy, histopathologic examination, antigen testing and confirmation and species characterization by PCR. Field evaluation of the new antigen detection kit approved by FDA in 2016 CL Detect™ IC-RDT was done and its results compared with other available diagnostic tests. RESULTS: A total of 14 cases with 25 skin lesions presented to the Skin OPD during the six month study period (January to June 2018). Out of these, 5 were males and 9 were females, average age being 32 yrs. Students and housewives of poor socio economic group were the most frequently affected groups. Lesions were found on the exposed areas of the body, mainly on the upper limbs and facial region. Majority of them were ulcerated plaques. Out of 14 cases under study, antigen test confirmed 7 positives; thereby yielding a positive rate of 50% against 71.4% for microscopy, 72.7% for PCR and a mere 38.5% for histopathology. Species characterization revealed Leishmania tropica as the causative organism. INTERPRETATION AND CONCLUSION: The study indicates that the number of cases have declined substantially over the past decade in Bikaner. Despite being the oldest technique used, microscopy still is a good option for diagnosis. Combined with PCR, diagnostic accuracy and hence utility is increased multifold. In its current form, IC-RDT may not be very useful.