Use of purified parasite proteins from Leishmania donovani for the rapid serodiagnosis of visceral leishmaniasis

Serodiagnosis of visceral leishmaniasis (VL) due to Leishmania donovani by using crude parasite antigen is complicated in many endemic areas because of cross-reactions with sera from humans with Chagas' disease. We used affinity-purified parasite proteins to develop a direct dot-blot assay for VL. Double-blind tests were carried out on sera from 40 patients with well-documented VL, from controls in endemic areas, and from patients with other diseases. Using gp70-2, 36 (90.0%) of 40 sera from patients with kala azar were correctly diagnosed; 1 (1.2%) of 86 sera from patients without kala azar was misdiagnosed. With dp72, 21 (100%) of 21 sera from patients with VL were correctly identified; 5 (7.0%) of 71 negative sera were misdiagnosed. None of the 18 sera from patients with Chagas' disease reacted positively against gp70-2. Our assay is rapid, simple, and specific and represents a new method for reliably diagnosing and monitoring VL.