Evaluation of Enzyme-Linked Immunosorbent Assay for Diagnosis of Post-Kala-Azar Dermal Leishmaniasis with Crude or Recombinant k39 Antigen

Abstract

The diagnosis of post-kala-azar dermal leishmaniasis (PKDL), a dermatosis that provides the only known reservoir for the parasite Leishmania donovani in India, remains a problem. Timely recognition and treatment of PKDL would contribute significantly to the control of kala-azar. We evaluated here the potential of the enzyme-linked immunosorbent assay (ELISA) as a diagnostic tool for PKDL. Antigen prepared from promastigotes and axenic amastigotes with parasite isolates that were derived from skin lesions of a PKDL patient gave sensitivities of 86.36 and 92%, respectively, in the 88 PKDL cases examined. The specificity of the ELISA test was examined by testing groups of patients with other skin disorders (leprosy and vitiligo) or coendemic infections (malaria and tuberculosis), as well as healthy controls from areas where this disease is endemic or is not endemic. A false-positive reaction was obtained in 14 of 144 (9.8%) of the controls with the promastigote antigen and in 14 of 145 (9.7%) of the controls with the amastigote antigen. Evaluation of the serodiagnostic potential of recombinant k39 by ELISA revealed a higher sensitivity (94.5%) and specificity (93.7%) compared to the other two antigens used. The data demonstrate that ELISA with crude or recombinant antigen k39 provides a relatively simple and less-invasive test for the reliable diagnosis of PKDL.

LeishmaniaPromastigote Membrane Antigen-Based Enzyme-Linked Immunosorbent Assay and Immunoblotting for Differential Diagnosis of Indian Post-Kala-Azar Dermal Leishmaniasis

“…The sensitivity of the IgG ELISA for LAg observed in the present study for the diagnosis of PKDL (100%) was even higher than that reported for PCR in Sudan (82.7%) (34) and India (93.8%) (46). The specificity of the assay (96.7%), although lower than those of PCR and the strip test with rK39 (100%) (46,47), was higher than the specificities of ELISAs with promastigote and amastigote antigen extracts and rK39 (45).…”

“…Most serological tests for the diagnosis of PKDL are of limited value in areas of endemicity, as they are also positive for kala-azar for patients with active and past cases of kala-azar (3,18,20,41,44,45,56). Even rK39 ELISA titers remain positive for up to 2 years after treatment, with no decline in OD values (54).…”

“…The IgG ELISA conducted with LAg appeared to be more sensitive than serodiagnosis with whole cells by a direct agglutination test (35,57), an IgG ELISA with total parasite antigen extract (45), as well as a strip test and an IgG ELISA with recombinant K39 (rK39) antigen (47,54) and other specific antigens (13). The sensitivity of the IgG ELISA for LAg observed in the present study for the diagnosis of PKDL (100%) was even higher than that reported for PCR in Sudan (82.7%) (34) and India (93.8%) (46).…”

“…Serological tests, including direct agglutination tests and enzyme-linked immunosorbent assays (ELISAs) based on crude or recombinant antigens, are highly sensitive (Ͼ90%) for the diagnosis of VL (27,43,53). On the other hand, serological tests for the diagnosis of PKDL demonstrate various sensitivities and specificities (10,45). These tests are based on the detection of antileishmanial immunoglobulin G (IgG) antibodies, which may persist for years after recovery from VL (25,54).…”

Seroprevalence of anti-Leishmania spp. antibodies in rural dogs from the city of Monte Negro, State of Rondônia, Brazil

“…ELISA methods using crude antigens of L. chagasi are considered less specific than IFAT, and can result in false-positive and negative reactions (SALOTRA et al, 2002). ELISA and IFAT methods using crude antigens are recommended by Brazilian Ministry of Health, but they show highly variable effectiveness to detect canine L. chagasi infection, mainly due to cross-reactivity of samples from dogs infected with other trypanosomatids such as L. braziliensis and Trypanosoma cruzi and low ability to detect seropositivity in asymptomatic dogs (PALATNIK-DE-SOUSA et al 2001).…”