Sensitivity of leishmanin skin test in patients of acute cutaneous leishmaniasis

Abstract

The leishmanin skin test (LST) is frequently used for clinical diagnosis of cutaneous leishmaniasis (CL). Although, LST is highly sensitive for CL, no definitive data exists as to how early in the disease does the test becomes positive. The study was aimed to evaluate the sensitivity of LST in early cases of CL. One hundred male patients with CL of not more than 2-weeks duration and having parasitologically proven diagnosis were enrolled in this study, carried out in a military hospital in Balochistan, Pakistan. LST was done by intradermal injection of 0.1 ml leishmanin on the volar surface of the forearm. The skin test reaction was read after 48 hours and then at 72 hours if the first reading was negative or marginal. If the initial test was negative, the LST was repeated after every 7 days until a positive reaction was produced. The total time from the onset of skin lesions until a positive LST was obtained was recorded for every patient. A positive LST was demonstrated in 78/100 patients with skin lesions of <or= 2 weeks duration, thus showing a sensitivity of 78 percent for this short duration. The sensitivity of LST increased to 94 percent and 98 percent for CL lesions of 4 and 6 weeks duration, respectively. LST is sensitive even in those CL patients who present with lesions of very recent onset. Thus the test can be employed with confidence, for the diagnosis of CL, even in early disease.