Detection of Anti-Leishmanial Antibodies in Patients' Sera

Diagnostic method using chemiluminescence and optical fiber immunosensor (OFIS) assays were evaluated for detecting anti-leishmanial antibodies in patients' sera. Leishmaniasis is a vector-borne disease caused by a flagellated protozoan parasite of the genus Leishmania, which affects both humans and animals.

Several serological tests are available for leishmaniasis including the indirect fluorescent antibody test (IFA), and enzyme-linked immunosorbant assay (ELISA), but each has limited sensitivity and specificity. Early infection with cutaneous leishmaniasis (CL) is associated with such a low level of antibody activity that it is sometimes undetectable.

Scientists from the Shraga Segal department of microbiology and immunology, the Ben Gurion University of the Negev (Beer Sheba, Israel) compared the efficacy of a chemiluminescence-enzyme-linked immunosorbant assay and an optical fiber immunosensor (OFIS) based on chemiluminesce, for the diagnosis of leishmaniasis, using highly sensitive and specific Leishmania antigens.

They found that the chemiluminescence-ELISA was 30 times more sensitive than the colorimetric-ELISA. The highest sensitivity (x60) was observed with the OFIS. However, high cross-reactivity was observed with sera from diseases such as malaria, toxocarosis, and strongyloidiasis patients. No cross- reactivity was demonstrated with sera from patients suffering from amoebiasis, toxoplasmosis, echinococosis, enterobiasis, and schistosomiasis.

The study suggested that the OFIS technique is very sensitive for the detection of anti-leishmanial antibodies in humans. Further studies using highly purified antigens are required to clarify the usefulness of the OFIS technique for diagnosis of the disease.

The study was presented by Lilach Eliyahu at the annual meeting of the Israel Society of Parasitology, Protozoology, and Tropical Medicine, which was held in Ramat Gan, Israel on December 17, 2008.

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Ben Gurion University of the Negev