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

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. Keywords: Kala-azar; Visceral Leishmaniasis; Diagnosis; KATEX; Latex; Buccal swab antigen detection

Antimicrobial properties and toxicity of Hagenia abyssinica (Bruce) J.F.Gmel, Fuerstia africana T.C.E. Fries, Asparagus racemosus (Willd.) and Ekebergia capensis Sparrm.

Background: The world health organization (WHO) estimates that 80% of population in Africa relies on traditional remedies for their healthcare. However, very few studies have been carried out to establish the therapeutic effects of these remedies. Objective: Four medicinal plants were investigated for antimicrobial activity and toxicity. Materials and Methods: Plants were collected from their natural habitat, dried, and extracted with organic and aqueous solvents. Antimicrobial activity was determined by the disc diffusion assay technique. In vitro cytotoxicity studies were carried out on extracts using MTT assay on Vero cell lines while acute toxicity in Swiss mice. Results: Extracts from H. abyssinica, F. africana and A. racemosus exhibited antibacterial activity with minimum inhibitory concentration of ≤ 6.25mg/ml against S. aureus, MRSA and P. aeruginosa. However, the plants studied had weak antifungal activity. H. abyssinica and F. africana extracts were found to be cytotoxic with CC50 of ˂ 90 µg/ml. These extracts were tested for acute toxicity and found to be safe at 5000 mg/kg body weight per day. Conclusion: The results of the study support the medicinal use of these plants and indicate that useful compounds from Hagenia abyssinica and Fuerstia africana can be isolated for further exploitation. Keywords: Medicinal plants, Antimicrobial activity, Cytotoxicity, Acute toxicit

A global comparative evaluation of commercial immunochromatographic rapid diagnostic tests for visceral leishmaniasis

Background: Poor access to diagnosis stymies control of visceral leishmaniasis (VL). Antibody-detecting rapid diagnostic tests (RDTs) can be performed in peripheral health settings. However, there are many brands available and published reports of variable accuracy. Methods: Commercial VL RDTs containing bound rK39 or rKE16 antigen were evaluated using archived human sera from confirmed VL cases (n = 750) and endemic non-VL controls (n = 754) in the Indian subcontinent (ISC), Brazil, and East Africa to assess sensitivity and specificity with 95% confidence intervals. A subset of RDTs were also evaluated after 60 days' heat incubation (37°C, 45°C). Interlot and interobserver variability was assessed. Results: All test brands performed well against ISC panels (sensitivity range, 92.8%-100%; specificity range, 96%-100%); however, sensitivity was lower against Brazil and East African panels (61.5%-91% and 36.8%-87.2%, respectively). Specificity was consistently > 95% in Brazil and ranged between 90.8% and 98% in East Africa. Performance of some products was adversely affected by high temperatures. Agreement between lots and readers was good to excellent (κ > 0.73-0.99). Conclusions: Diagnostic accuracy of VL RDTs varies between the major endemic regions. Many tests performed well and showed good heat stability in the ISC; however, reduced sensitivity against Brazilian and East African panels suggests that in these regions, used alone, several RDTs are inadequate for excluding a VL diagnosis. More research is needed to assess ease of use and to compare performance using whole blood instead of serum and in patients coinfected with human immunodeficiency virus