Performance of serological tests available in Brazil for the diagnosis of human visceral leishmaniasis

Background Visceral leishmaniasis (VL) is the most severe form of leishmaniasis and is potentially fatal if not diagnosed and treated. Accurate and timely diagnosis is considered one of the pillars needed for the reduction in disease-related lethality. Brazil is currently one of the three eco-epidemiological hotspots for this disease. Several serological tests are commercially available in this country for VL diagnosis, although information on the performance of these tests is fragmented and insufficient. The aim of this study was to directly compare the performance of six commercial kits: three enzyme-linked immunosorbent assays (ELISAs), two immunofluorescence antibody tests (IFATs), one immunochromatographic test (ICT), besides one ICT, currently not commercially available in Brazil and one in-house direct agglutination test (DAT-LPC), not yet marketed. Methodology/Principal findings A panel of 236 stored samples from patients with clinically suspected VL, including 77 HIV-infected patients, was tested. IT-LEISH and DAT-LPC showed the highest accuracy rate among the non-HIV-infected patients, 96.2% [CI95%: 92.8-99.7%] and 95.6% [CI95%: 91.9-99.3%], respectively. For the ELISA tests evaluated, the maximum accuracy was 91.2%, and in the inter HIV-status group analysis, no significant differences were observed. For both IFATs evaluated, the maximum accuracy was 84.3%, and a lower accuracy rate was observed among the HIV-infected patients (p = 0.039) than among the non-HIV-infected patients. The DAT-LPC was the most accurate test in the HIV-infected patients (p <= 0.115). In general, no significant difference in accuracy was observed among the VL-suspected patients stratified by age. Conclusions/Significance In summary, the differences in the performance of the tests available for VL in Brazil confirm the need for local studies before defining the diagnostic strategy. Author summary Visceral leishmaniasis (VL) is a tropical disease distributed worldwide. In the Americas, Brazil reports about 96% of VL cases, which has been highlighted by the increase in lethality in last years. Accurate VL diagnosis is of utmost importance. Despite this, the performance of some commercial tests currently available in Brazil is unknown, especially for HIV-infected patients. Accordingly, in this study we present a comparative performance analysis of six commercial kits available in Brazil for the diagnosis of VL in non-HIV and HIV-infected patients, besides one immunochromatographic test (ICT) and one in-house direct agglutination test (DAT-LPC) currently not commercially available in Brazil. ICTs and DAT-LPC showed better performance among non-HIV infected patients. Despite the known limitation of serological tests for the diagnosis of patients with HIV, the direct agglutination test was more accurate in this specific group of patients. Our results demonstrate significant differences in the performance of different serological tests and confirm that the use of serology should be qualified with previous information on the performance of the tests.