Evaluation of leishmanin skin test in Indian visceral leishmaniasis

We evaluated the performance of the leishmanin skin test (LST) in 50 patients with visceral leishmaniasis (VL), 124 cured VL patients at different time intervals, 125 healthy controls from an endemic region (HEC), and 14 healthy controls from a non-endemic region (NEHC). The leishmanin antigen used was based on Leishmania major and was obtained from the Pasteur Institute (Iran). A positive LST was found in 14.0% of patients with active VL, 40.3% of cured patients, 21.6% of HECs, and 0% in NEHCs. The 14% positivity in patients with active VL conflicts with the widely held opinion that such patients should be negative because of anergy. Also, a lack of sensitivity of the LST was observed in cured VL patients. An LST antigen produced from L. donovani strains from India should be explored.