TY - JOUR
T1 - Application of an improved method for the recombinant K39 enzyme-linked immunosorbent assay to detect visceral leishmaniasis disease and infection in Bangladesh
AU - Kurkjian, K. M.
AU - Vaz, L. E.
AU - Haque, R.
AU - Cetre-Sossah, C.
AU - Akhter, S.
AU - Roy, S.
AU - Steurer, F.
AU - Amann, J.
AU - Ali, M.
AU - Chowdhury, R.
AU - Wagatsuma, Y.
AU - Williamson, J.
AU - Crawford, S.
AU - Breiman, R. F.
AU - Maguire, J. H.
AU - Bern, C.
AU - Secor, W. E.
PY - 2005/12
Y1 - 2005/12
N2 - Several serology-based immunoassays are used to diagnose visceral leishmaniasis (VL), a chronic protozoan parasitic disease caused by the Leishmania donovani complex. These tests are primarily designed to diagnose the most severe clinical form of VL, known as kala-azar. However, leishmanial infection is frequently asymptomatic and may manifest only as a positive serologic response or positive leishmanin skin test. We modified a previously described enzyme-linked immunosorbent assay (ELISA) that detects patient antibodies reactive with the recombinant Leishmania protein K39 (rK39) to confirm suspected kala-azar and to detect asymptomatic infection in a community study in Bangladesh. With the inclusion of a standard curve on each ELISA plate, the rK39 ELISA was more repeatable (kappa coefficient of agreement = 0.970) and more reliable compared to the original method (kappa = 0.587, P < 0.001). The cutoff point for a positive antibody response was chosen based on the 99th percentile of the ELISA distribution for the negative-control sera. However, we found that sera from all patients with active kala-azar yielded values more than twice the magnitude of this cutoff. Using receiver-operator characteristic curves, we determined a second cutoff value predictive of kala-azar. Using these criteria, the sensitivity and specificity of the modified ELISA for kala-azar were 97.0% and 98.9%, respectively, for sera from our study population. We hypothesize that individuals with antibody levels greater than the 99th percentile of the negative controls but less than the cutoff point for kala-azar have asymptomatic leishmanial infections.
AB - Several serology-based immunoassays are used to diagnose visceral leishmaniasis (VL), a chronic protozoan parasitic disease caused by the Leishmania donovani complex. These tests are primarily designed to diagnose the most severe clinical form of VL, known as kala-azar. However, leishmanial infection is frequently asymptomatic and may manifest only as a positive serologic response or positive leishmanin skin test. We modified a previously described enzyme-linked immunosorbent assay (ELISA) that detects patient antibodies reactive with the recombinant Leishmania protein K39 (rK39) to confirm suspected kala-azar and to detect asymptomatic infection in a community study in Bangladesh. With the inclusion of a standard curve on each ELISA plate, the rK39 ELISA was more repeatable (kappa coefficient of agreement = 0.970) and more reliable compared to the original method (kappa = 0.587, P < 0.001). The cutoff point for a positive antibody response was chosen based on the 99th percentile of the ELISA distribution for the negative-control sera. However, we found that sera from all patients with active kala-azar yielded values more than twice the magnitude of this cutoff. Using receiver-operator characteristic curves, we determined a second cutoff value predictive of kala-azar. Using these criteria, the sensitivity and specificity of the modified ELISA for kala-azar were 97.0% and 98.9%, respectively, for sera from our study population. We hypothesize that individuals with antibody levels greater than the 99th percentile of the negative controls but less than the cutoff point for kala-azar have asymptomatic leishmanial infections.
UR - http://www.scopus.com/inward/record.url?scp=29144512352&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=29144512352&partnerID=8YFLogxK
U2 - 10.1128/CDLI.12.12.1410-1415.2005
DO - 10.1128/CDLI.12.12.1410-1415.2005
M3 - Article
C2 - 16339064
AN - SCOPUS:29144512352
SN - 1071-412X
VL - 12
SP - 1410
EP - 1415
JO - Clinical and Diagnostic Laboratory Immunology
JF - Clinical and Diagnostic Laboratory Immunology
IS - 12
ER -