Detection of Leishmania Antigen from Buccal Swabs in Kala-azar Patients Using KATEX Method

Abstract

Visceral leishmaniasis (VL) or kala-azar is a chronic protozoan infection in humans that is fatal unless treated and is associated with significant global morbidity and mortality. Confirmation of visceral leishmaniasis (VL) diagnosis requires microscopic examination to visualize the causative agent Leishmania Donovani in spleen or bone marrow aspirate. Kala-azar latex agglutination based test (KATEX) antigen test for VL in buccal swabs has not been evaluated locally and could offer a significant advantage in screening patients suspected of VL. The study was conducted after approval from KEMRI Scientific Ethical Review Unit (SERU). Buccal swabs were obtained from VL cases and controls patients presenting at Kimalel Health Centre, Baringo County, Kenya. Latex agglutination based test (KATEX) was used to detect parasite antigen in buccal swabs. The study evaluated the ability to use KATEX, a simple non-invasive diagnostic test to detect leishmania antigens in buccal swabs, determine the ability of the kit to detect leishmania antigens in buccal cells of kala-azar patients and compare the sensitivity and specificity of KATEX - buccal assay using microscopy as the gold standard. Eighty eight samples were analyzed using statistics and data (STATA) software version 13.2 standard edition, including 44 VL and 44 non-VL patients. KATEX kit was able to detect visceral leishmaniasis antigens from buccal swabs giving a sensitivity of (81.8%; 95%CI: 67.3% to 91.8% and specificity of (79.5%; 95%CI: 64.7 –90.2%). Buccal swab test assay using KATEX is an easy test to perform and promising non-invasive based antigen detection test which may be useful for screening kala-azar patients and could be applied in the diagnosis of VL. It is a functional assay that warrants a larger study with a larger sample size for the purpose of evaluating the utility of the test in diagnosing visceral leishmaniasis.