Serodiagnosis of Visceral Leishmaniasis in Northeastern Italy: Evaluation of Seven Serological Tests

Abstract

This study compares the performance of seven assays, including two ELISA (Leishmania ELISA IgG + IgM, Vircell Microbiologists; Leishmania infantum IgG ELISA, NovaTec), three rK39-based immunochromatographic tests (rK39-ICTs) (Leishmania Dipstick Rapydtest, Apacor; On Site Leishmania IgG/IgM Combo Rapid Test, CTK Biotech; LEISHMANIA Strip quick Test, Cypress Diagnostic), one indirect immunofluorescent antibody test (IFAT) (Leishmania-Spot IF, BioMérieux), and one western blot (WB) (Leishmania WESTERN BLOT IgG, LDBio Diagnostics) for serodiagnosis of visceral leishmaniasis (VL). Serum samples from 27 VL patients living in northeastern Italy were analyzed, as well as the serum samples from 50 individuals in whom VL diagnosis was excluded. The WB and the IFAT had 96% sensitivity, followed by the ELISA (63% and 74%, respectively). The rK39-ICT exhibited the worst performance among the serological tests, with sensitivities ranging from 52% to 70%. By combining selected ELISA/ICT, the sensitivity of VL detection reached 89%. IFAT and WB outperformed ELISA and rK39-ICT by possessing optimal sensitivity, but their high cost and complexity of execution would not allow their employment as screening tests. In conclusion, the combination of easy-to-perform tests, such as ICT and ELISA, could improve sensitivity in the serodiagnosis of Mediterranean VL.

Laboratory diagnostics for human Leishmania infections: a polymerase chain reaction-focussed review of detection and identification methods

“…The antigen load may not be sufficient in early infection for detection; conversely, because antigen-specific antibodies persist long after cure, active relapsed disease cannot always be discerned [ 61 , 103 ]. Furthermore, these tests are less accurate for immunocompromised patients, and cross-reactivity is reported with other diseases endemic to Leishmania -affected areas, including Chagas disease [ 53 , 88 , 104 – 108 ]. Simplified assays have been introduced, such as the rK39 immunochromatographic assay (ICT), the direct agglutination test, the indirect fluorescent antibody test and latex agglutination testing [ 109 ].…”

Test combination to detect latent Leishmania infection: A prevalence study in a newly endemic area for L. infantum, northeastern Italy

“…The strength of this study was to select three sensitive assays to detect Leishmania infection (kDNA Real-Time PCR, WB and WBA) and ensuring that a case with a positive result of any test within the combination was counted as positive. By selecting the most sensitive methods that are available for the diagnosis of VL [ 20 , 21 , 25 , 33 ] and for the detection of anti-leishmanial cell mediated response [ 11 , 24 ], we believe that the sensitivity of our test combination in detecting latent leishmaniasis is high.…”

“…A number of studies have used serological tests to identify this asymptomatic infection; Leishmania -specific antibodies have been detected by rk39 immunochromatographic tests, immunoenzymatic tests, direct agglutination tests and immunofluorescent antibody titration [ 17 , 18 , 19 ]; nevertheless these tests may exhibit scarce sensitivity in identification of latent leishmaniasis [ 20 ].…”

Urine-Based Molecular Diagnostic Tests for Leishmaniasis Infection in Human and Canine Populations: A Meta-Analysis

“…Specialized lab equipment and expert staff are mandatory, the sensitivity is rather low, and the procedure poses discomfort and risk to both subjects and health professionals [33]. An approach to surpass the above issues is the use of serological tests which show improved sensitivity and specificity and are less risky (for subjects and staff), however co-infections or past infections can mislead health professional to treatment strategy decisions [2,34]. In the 21st century, urine samples have gradually been used for the detection of cell-free circulating DNA (cfDNA) spanning 150 to 250 bp coming from apoptotic, cancerous, or infected cells [9,35].…”