Evaluation of IgG anti-L. tropica antibody response as a biomarker for cutaneous leishmaniasis using ELISA in endemic regions of Pakistan

Cutaneous leishmaniasis (CL) has diverse clinical manifestations that overlap with other skin conditions. Conventional diagnostic methods, such as microscopy, often lack sensitivity and make diagnosis a challenge due to varying sensitivity and specificity, highlighting the need for sensitive and cost-effective immunodiagnostic alternatives. The present study aimed to evaluate anti-leishmanial immunoglobulin G (IgG anti-L. tropica) antibody responses as a biomarker of CL. The lesional aspirate and serum samples from CL-infected individuals (n = 216) and healthy controls (n = 157) were collected from CL endemic regions of Punjab, Khyber Pakhtunkhwa (KPK) and Balochistan in Pakistan. Leishmania tropica (L. tropica) was identified as a dominant species via real-time ITS1 PCR. The soluble Leishmania antigen was prepared from cultured L. tropica and utilized to detect levels of Leishmania-specific IgG anti-L. tropica antibodies in sera employing enzyme-linked immunosorbent assay (ELISA). The ELISA demonstrated significantly higher IgG anti-L. tropica levels in CL patients (P < 0.0001) as compared to healthy controls. A cut-off value of 0.22 yielded a sensitivity of 79.35 % and specificity of 84.40 %, with an Area Under Curve (AUC) of 0.79. IgG anti-L. tropica levels. A significant difference in IgG anti-L. tropica levels of antibody was observed among CL patients with different lesion sizes and numbers. The developed ELISA highlighted the importance of employing reliable diagnostic techniques for CL. The serological approach may complement conventional diagnostics and contribute to better disease management in endemic settings.