Heterogeneity of Leishmania donovani Parasites Complicates Diagnosis of Visceral Leishmaniasis: Comparison of Different Serological Tests in Three Endemic Regions

Abstract

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.

The use ofEscherichia colitotal antigens as a complementary approach to address seropositivity toLeishmaniaantigens in canine leishmaniosis

“…Still, regional differences in antigen performance have been already reported, the performance of rK39 (for the human visceral leishmaniasis) is known to be diminished in subSaharan Africa (Pattabhi et al 2010;Bezuneh et al 2014;Mukhtar et al 2015). Subtle genetic differences in Leishmania strains are sufficient to influence the performance of the recombinant antigens (Abass et al 2015).…”

Development and Validation of a PCR-ELISA for the Diagnosis of Symptomatic and Asymptomatic Infection byLeishmania (Leishmania) infantum

“…Some studies demonstrated that serological tests based on antigens of a single Leishmania sp. exhibited low diagnostic performance in regions with circulating heterologous parasites [5, 6]. The serological tests, with the exception of the Direct Agglutination Tests (DAT) and Western blotting, exhibit low sensitivity in VL patients coinfected with HIV [7–9] because of their insufficient immune humoral response.…”

Opportunistic Oral Infections

“…Additional challenges in diagnostic microbiology include heterogeneity in laboratory methodology, lack of universal standardization or harmonization, and microbial heterogeneity. 16,17 …”