Comparison of Different Serological Tests in Three Endemic Regions

Diagnostic tests for visceral leishmaniasis that are based on antigens of a single Leishmania strain can have low diagnostic performance in regions where heterologous parasites predominate. The aim of this study was to investigate and compare the performance of five serological tests, based on different Leishmania antigens, in three endemic countries for visceral leishmaniasis. A total number of 231 sera of symptomatic and asymptomatic cases and controls from three endemic regions of visceral leishmaniasis in East Sudan, North India and South France were evaluated by following serological tests: rKLO8- and rK39 ELISA, DAT (ITMA-DAT) and two rapid tests of rK39 (IT LEISH) and rKE16 (Signal-KA). Overall, rKLO8- and rK39 ELISA were most sensitive in immunocompetent patients from all endemic regions (96–100%) and the sensitivity was reduced to 81.8% in HIV co-infected patients from France. Sera of patients from India demonstrated significantly higher antibody responses to rKLO8 and rK39 compared with sera from Sudan (p<0.0001) and France (p<0.0037). Further, some Indian and Sudanese patients reacted better with rKLO8 than rK39. Sensitivity of DAT (ITMA-DAT) was high in Sudan (94%) and India (92.3%) but low in France being 88.5% and 54.5% for VL and VL/HIV patients, respectively. In contrast, rapid tests displayed high sensitivity only in patients from India (96.2%) but not Sudan (64–88%) and France (73.1–88.5% and 63.6–81.8% in VL and VL/HIV patients, respectively). While the sensitivity varied, all tests showed high specificity in Sudan (96.7–100%) and India (96.6%).Heterogeneity of Leishmania parasites which is common in many endemic regions complicates the diagnosis of visceral leishmaniasis. Therefore, tests based on homologous Leishmania antigens are required for particular endemic regions to detect cases which are difficult to be diagnosed with currently available tests

Development of a Dipstick Assay for Detection of Leishmania-Specific Canine Antibodies

A dipstick assay, based on Leishmania infantum antigen, for the rapid detection of Leishmania-specific antibodies in canine serum samples was developed and evaluated. After determination of optimal dipstick test conditions, test performance was compared with two existing serological tests, i.e., the direct agglutination test (DAT) and the fast agglutination screening test (FAST). In the present study the dipstick test had a sensitivity of 99.2% and a specificity of 87.9%. The DAT had a sensitivity of 97.7% and a specificity of 95.2%, whereas the FAST had also a sensitivity of 97.7% and a specificity of 93.0%. High degrees of agreement were observed between the dipstick test and DAT (93.7%; κ value, 0.86), between the dipstick test and FAST (91.8%; κ value, 0.82), and between the DAT and FAST (95.2%; κ value, 0.90). The high sensitivity and ease of performance make the dipstick test very suitable for surveillance surveys

Heterogeneity of Leishmania donovani parasites complicates diagnosis of visceral leishmaniasis: comparison of different serological tests in three endemic regions.

Diagnostic tests for visceral leishmaniasis that are based on antigens of a single Leishmania strain can have low diagnostic performance in regions where heterologous parasites predominate. The aim of this study was to investigate and compare the performance of five serological tests, based on different Leishmania antigens, in three endemic countries for visceral leishmaniasis. A total number of 231 sera of symptomatic and asymptomatic cases and controls from three endemic regions of visceral leishmaniasis in East Sudan, North India and South France were evaluated by following serological tests: rKLO8- and rK39 ELISA, DAT (ITMA-DAT) and two rapid tests of rK39 (IT LEISH) and rKE16 (Signal-KA). Overall, rKLO8- and rK39 ELISA were most sensitive in immunocompetent patients from all endemic regions (96-100%) and the sensitivity was reduced to 81.8% in HIV co-infected patients from France. Sera of patients from India demonstrated significantly higher antibody responses to rKLO8 and rK39 compared with sera from Sudan (p<0.0001) and France (p<0.0037). Further, some Indian and Sudanese patients reacted better with rKLO8 than rK39. Sensitivity of DAT (ITMA-DAT) was high in Sudan (94%) and India (92.3%) but low in France being 88.5% and 54.5% for VL and VL/HIV patients, respectively. In contrast, rapid tests displayed high sensitivity only in patients from India (96.2%) but not Sudan (64-88%) and France (73.1-88.5% and 63.6-81.8% in VL and VL/HIV patients, respectively). While the sensitivity varied, all tests showed high specificity in Sudan (96.7-100%) and India (96.6%).Heterogeneity of Leishmania parasites which is common in many endemic regions complicates the diagnosis of visceral leishmaniasis. Therefore, tests based on homologous Leishmania antigens are required for particular endemic regions to detect cases which are difficult to be diagnosed with currently available tests

Reactivity of VL sera from different endemic regions in rKLO8- and rK39 ELISA.

<p>OD values of VL sera from Sudan (n = 50), India (n = 26) and France with negative (HIV-, n = 26) or positive (HIV+, n = 11) HIV were tested in rKLO8- or rK39 ELISA at dilutions of 1:800. Means ODs of VL sera from the different regions were compared. Dots represent values for individual sera and horizontal line represents cut-off values (0.12). Significance was determined by unpaired Student's <i>t</i> test at 95% confidence intervals and P-values < 0.05 indicate statistically significant differences; ns indicates no significant differences.</p

Comparison of anti-<i>Leishmania</i> antibody responses in rKLO8- and rK39 ELISA using patient and control sera from three endemic regions.

<p>Protein concentrations of 5ng/100μl rKLO8 or rK39 were tested with sera of patients and controls from Sudan (A), India (B) and France (C). Sera were tested at dilutions of 1:800. A cut off value of 0.12 was established as means + 3 SD of 30 healthy controls. VL, visceral leishmaniasis; VLS, VL suspects; HC, healthy control; MA, malaria; TP, toxoplasmosis; VL/HIV, VL and HIV, ASC, asymptomatic cases. The black horizontal lines represent cut off values. OD values of 0.6 (5 fold of cut off) and 2.15 are shown in dotted lines.</p