ELISA based evaluation of antibody response to Leishmania in a region endemic for cutaneous leishmaniasis

Abstract

Aims: Leishmaniasis includes several clinical forms. While routine diagnosis of cutaneous leishmaniasis (CL) is by microscopy, an antibody response to CL has been reported in several recent studies. This study evaluated anti-leishmanial IgG antibody responses as a biomarker of active leishmaniasis and a measure of exposure to Leishmania. Methods and results: Sera from 50 untreated CL patients, 140 patients under treatment and 280 healthy individuals residing in endemic regions collected as part of an epidemiological survey, was analysed with an ELISA established in-house using receiver-operator-characteristic (ROC) curve at optimised cut-off value. The assay showed high performance as a diagnostic tool in identifying exposure in endemic individuals (sensitivity: 98%, specificity: 90.3%). All patients showed lower antibody levels over time since onset of lesion/s. Antibody levels were higher (p ˂ 0.01) and persisted for a longer period in untreated patients. In patients under treatment, the level of anti-IgG antibodies was negatively correlated with the total duration the patient had been on treatment. Conclusion: The anti-leishmanial IgG response in L. donovani induced CL is transient and is unlikely to confer protective immunity. Optimised serological assays may be useful in endemic settings for diagnosis and monitoring the treatment response in CL.