Abstract:
Background: 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 usually in spleen or bone marrow aspirate. Tissue aspiration is invasive, potentially risky and require
skilled personnel. KATEX (Kalon biologicals) antigen test for VL in buccal swabs has not been evaluated
locally and could offer a significant advantage in screening patients suspected of VL. Method: A cross sectional
study was conducted after receiving approval from KEMRI SERU. We obtained buccal swabs from patients
presenting at Kimalel Health Centre, Baringo County, Kenya from VL cases and controls. VL was defined as
patients meeting VL case definition with positive splenic aspirate microscopy while endemic controls were
defined as patients presenting to the health center with no fever and no prior history of Kala azar but living in VL
endemic. Latex agglutination based test (KATEX) was used to detect parasite antigen in buccal swabs. It was a
proof of principle study carried out to explore 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. Results: 88 patients were analyzed, including 44 VL and 44 non-VL patients.
The median age of VL patients was 18 years with predominance of males (68.2%). None of the tested VL
patients were co-infected with HIV. KATEX kit was able to detect visceral leishmaniasis antigens from the
buccal swabs giving a sensitivity of (81.8%; 95%CI: 67.3% to 91.8%, specificity of (79.5%; 95%CI: 64.7 –
90.2%), Positive predictive value n= 36(80.0%); 95%CI: 65.4% to 90.4% and Negative predictive values n =
35(81.4%); 95% CI: 66.6% to 91.6%. Conclusion and Recommendation: 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. There is dire need to identify non-invasive, less risky and field adapted point of care diagnostics
for VL
