Development of a latex agglutination test based on VH antibody fragment for detection of Streptococcus suis serotype 2.

Streptococcus suis serotype 2 (SS2) is an important porcine pathogen that causes diseases in both swine and human. For rapid SS2 identification, a novel latex agglutination test (LAT) based on heavy-chain variable domain antibody (VH) was developed. Firstly, the soluble 47B3 VH antibody fragment from a phage display library, in which cysteine residues were engineered at the C-terminus, was expressed in Escherichia coli. The purified protein was then gently reduced to form monomeric soluble 47B3 VH subsequently used to coat with latex beads by means of site-specific conjugation. The resulting VH-coated beads gave a good agglutination reaction with SS2. The LAT was able to distinguish S. suis serotype 2 from serotype 1/2, which shares some common sugar residues, and showed no cross-reaction with other serotypes of S. suis or other related bacteria. The detection sensitivity was found to be as high as 1.85x106 cells. The LAT was stable at 4°C for at least six months without loss of activity. To the best of our knowledge, this is the first LAT based on a VH antibody fragment that can be considered as an alternative for conventional antibody-based LAT where VHs are the most favored recombinant antibody.

Serum Helicobacter pylori antibody reactivity in seven Asian countries using an automated latex aggregation turbidity assay.

BACKGROUND AND AIM: To determine the application range of diagnostic kits utilizing anti-Helicobacter pylori antibody, we tested a newly developed latex aggregation turbidity assay (latex) and a conventional enzyme-linked immunosorbent assay (E-plate), both containing Japanese H. pylori protein lysates as antigens, using sera from seven Asian countries. METHODS: Serum samples (1797) were obtained, and standard H. pylori infection status and atrophy status were determined by culture and histology (immunohistochemistry) using gastric biopsy samples from the same individuals. The two tests (enzyme-linked immunosorbent assay and latex) were applied, and receiver operating characteristics analysis was performed. RESULTS: Area under the curve (AUC) from the receiver operating characteristic of E-plate and latex curves were almost the same and the highest in Vietnam. The latex AUC was slightly lower than the E-plate AUC in other countries, and the difference became statistically significant in Myanmar and then Bangladesh as the lowest. To consider past infection cases, atrophy was additionally evaluated. Most of the AUCs decreased using this atrophy-evaluated status; however, the difference between the two kits was not significant in each country, but the latex AUC was better using all samples. Practical cut-off values were 3.0 U/mL in the E-test and 3.5 U/mL in the latex test, to avoid missing gastric cancer patients to the greatest extent possible. CONCLUSIONS: The kits were applicable in all countries, but new kits using regional H. pylori strains are recommended for Myanmar and Bangladesh. Use of a cut-off value lower than the best cut-off value is essential for screening gastric cancer patients.

Evaluation of the diagnostic potential of recombinant leptospiral OMP A-like protein (Loa22) and transmembrane (OmpL37) protein in latex agglutination test for serodiagnosis of leptospirosis in animals.

Leptospirosis is a re-emerging zoonotic disease of animals and humans caused by pathogenic Leptospira, which has major public health concerns. The study is aimed to express the recombinant outer membrane protein (OMP) A-like protein (rLoa22) and transmembrane (rOmpL37) protein of Leptospira interrogans serovar Hardjo in the Escherichia coli and their evaluation as a diagnostic antigen in the latex agglutination test (LAT) to detect anti-leptospiral antibodies in the sera of animals. The Loa22 and OmpL37 genes lacking signal peptide coding sequences were individually amplified (522 and 963 bp), by polymerase chain reaction, and directionally cloned into a pETite N-His Kan vector for expression. The expressed purified proteins were characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblot, which confirmed leptospiral specific reactive protein with a molecular weight of ~19 and 36 kDa, respectively. The sensitized latex beads coated with these OM proteins separately were evaluated in LAT using cattle sera of microscopic agglutination test (MAT) confirmed positive (n = 53) and negative (n = 52) cases of leptospirosis. The rLoa22 LAT and rOmpL37 LAT revealed the relative diagnostic sensitivity of 94·34 and 96·23%, diagnostic specificity of 92·31 and 96·15% and accuracy of 93·33 and 96·19%, with the excellent agreement of Cohen's kappa value of 0·87 and 0·92, respectively. After extensive evaluation, this rapid recombinant protein-based field diagnostic test can be applied as a screening test for the detection of anti-leptospiral antibodies in the sera of animals in the field conditions.

A novel site-specific chemical conjugation of IgG antibodies by affinity peptide for immunoassays.

Recently, there has been an increasing interest in site-specific modifications of antibodies used in immunoassays for disease diagnosis and as antibody therapeutics, such as antibody-drug conjugates. Previously, we established a site-specific chemical conjugation system using an IgG-Fc binding chemical conjugation affinity peptide (CCAP). CCAP could be used only for the modification of human IgG owing to the lack of affinity of CCAP to rodent IgG molecules. In this study, novel CCAP reagents are proposed, which can be used for both human and mouse IgG, based on the Staphylococcus aureus protein A domain-derived affinity peptides Z34C and Z33. Compared with the activity of a conventional randomly modified antibody, mouse IgG modified using this method had favourable features in two immunoassays, demonstrating the advantages of the proposed CCAP method in preserving antibody functionality during conjugation.

Comparison of the specificity of rheumatoid factor detected by latex fixation with that of regulatory rheumatoid factor.

BACKGROUND: Rheumatoid factor (RF), originally defined as pathological autoantibodies to IgG that are detected in rheumatoid arthritis, turned out to be multi-specific antibodies, some of which exhibit immunoregulatory properties. Recently, we identified a RF, the production of which confers resistance to experimental autoimmune diseases and is associated with the remission of autoimmune diseases. To differentiate the RF, we discovered from the one associated with rheumatic disease onset or progression and to reflect its immunoregulatory properties, we named it regulatory rheumatoid factor (regRF). Immunization with conformers of Fc fragments that expose regRF neoepitopes reduces collagen-induced arthritis in rats. Certain information about the specificity of classical RF and regRF indicates that these populations may be one and the same. Therefore, the aim of this study was to determine whether there is a difference between the classical RF and regRF. METHODS: Classical RF was measured in diseased blood by the latex fixation method, and regRF was detected by the agglutination of human IgG-loaded tanned erythrocytes. Competitive analysis was used to determine the specificity of rheumatoid factors. RESULTS: It was found that regRF and pathology-associated RF constitute different antibody populations. Pathology-associated RF is specific for lyophilized IgG. RegRF does not interact with IgG. RegRF is specific to conformers of IgG Fc fragments that have a reduced hinge. In latex-positive rheumatoid arthritis sera, regRF may be present in addition to pathology-associated RF. The latex fixation method detects both rheumatoid factor populations. CONCLUSION: RegRF and classical pathology-associated RF have different specificity.

Contrasting Results from Two Commercial Kits Testing for the Presence of Clostridium perfringens Enterotoxin in Feces from Norovirus-Infected Human Patients.

BACKGROUND: Detection of Clostridium perfringens enterotoxin (CPE) is critical for disease surveillance; however, commercial testing kits produce contrasting results. METHODS: We examined the cause of the differing results from a reversed passive latex agglutination (RPLA) assay (PET-RPLA Toxin Detection Kit) and an enzyme-linked immunosorbent assay (C. perfringens Enterotoxin ELISA Kit) using 73 human norovirus-positive fecal samples from gastroenteritis patients across 22 episodes in Japan. RESULTS: CPE was detected in 39/73 samples using the RPLA method; however, ELISA-based examination of 10 RPLA-positive samples produced negative results. Moreover, cpe was not detected in any of the RPLA-positive (n = 32) or -negative (n = 5) samples, and C. perfringens was only isolated from one RPLA-positive sample. CONCLUSIONS: An ELISA-based testing approach may be more reliable than RPLA assays for CPE detection from human fecal samples. These findings may also be applicable to the detection of other foodborne diseases.

Comparison of two new in-house Latex Agglutination Tests (LATs), based on the DnaK and Com1 synthetic peptides of Coxiella burnetii, with a commercial indirect-ELISA, for sero-screening of coxiellosis in bovines.

The in-house developed DnaK and Com1 synthetic peptide-based Latex Agglutination Tests (LATs) were comparatively evaluated with commercial indirect-ELISA kit, to provide a rapid, economical and onsite field applicable test for seroscreening of coxiellosis in bovines.

Evaluation of a commercial latex agglutination test for detecting rotavirus A and human adenovirus in children's stool specimens.

OBJECTIVES: Rotavirus A and human adenovirus are the two most common causes of infantile diarrhea; thus, it is of great importance to find out a rapid and accurate diagnostic method. This study aimed to evaluate the diagnostic significance of latex agglutination test for detection of rotavirus A and human adenovirus. METHODS: A prospective study was conducted on 214 diarrhea children from September 2018 to March 2019 in our hospital. Fresh stool samples were collected for detection of rotavirus A and human adenovirus by latex agglutination test and quantitative reverse transcription polymerase chain reaction (RT-qPCR). Then, the consistency of results detected by these two methods was analyzed． RESULTS: With performing the latex agglutination test, it was revealed that positive rates for detecting rotavirus A virus and human adenovirus were 23.83% (51/214) and 25.24% (54/214), respectively. Meanwhile, results of RT-qPCR showed that positive rates for detecting rotavirus A virus and human adenovirus were 58 (27.10%) and 59 (27.57%), respectively. Using RT-qPCR as the gold standard, the sensitivity and specificity of the latex agglutination test for detecting rotavirus A were 81.03% and 97.44%, and the corresponding values for detecting human adenovirus were 76.27% and 94.19%, respectively. CONCLUSION: This latex agglutination test showed a satisfactory consistency with RT-qPCR for detecting rotavirus A and human adenovirus. The mentioned commercial assay may be highly appropriate for rapid screening of rotavirus A and human adenovirus.

Point of care testing evaluation of lateral flow immunoassay for diagnosis of cryptococcus meningitis in HIV-positive patients at an urban hospital in Nairobi, Kenya, 2017.

OBJECTIVES: The objective of this study was to evaluate the performance of lateral flow immunoassay (LFA) against latex agglutination (LA), India ink and culture in point-of-care diagnosis of cryptococcus meningitis (CM). We conducted cross-sectional study among HIV-positive patients with suspected CM at Mbagathi Hospital, Nairobi, April-July 2017. RESULTS: Of 124 capillary blood and serum and 99 cerebrospinal fluid (CSF) samples, LFA and LA had a concurrence on serum of 94.4%, kappa (0.88), sensitivity (100%) and specificity (91%). LFA and LA on CSF, was 97.9%, kappa (0.96), sensitivity (100%) and specificity (96%). LFA and India ink was 96.9%, kappa (0.94), sensitivity (100%) and specificity (94.1%). On CSF culture, concurrence was 72.7%, kappa (0.43), sensitivity (100%) and specificity (64%) and of LFA on capillary blood, serum and CSF was 100% with kappa (1.00), sensitivity and specificity of 100%.

Comparison of performance characteristics between high-performance liquid chromatography and latex agglutination turbidimetric immunoassay for therapeutic drug monitoring of zonisamide.

BACKGROUND: Recently, the Nanopia® TDM Zonisamide reagent using the latex particle-enhanced turbidimetric immunoassay (LTIA) method was developed. The aim of this study was to compare the differences in serum zonisamide (ZNS) concentrations quantified by the high-performance liquid chromatography (HPLC) method and the LTIA method using a TBA-25FR analyzer. METHODS: A total of 78 samples from 33 patients were quantified by both HPLC and LTIA methods. Deproteinization was used as pretreatment for the HPLC method. The ZNS concentrations quantified by two methods were compared. RESULTS: The HPLC method had intra- and inter-day precision lower than 1.86% and 9.00%, and accuracy better than 2.44% and 6.33%, respectively. The LTIA method showed intra- and inter-day precision lower than 2.50% and 5.20%, and accuracy better than 15.80% and 10.60%, respectively. The lower limits of quantification for the HPLC and LTIA methods were 1.0 and 5.0 µg/mL, respectively. The ZNS concentration quantified by the HPLC method correlated strongly with that by the LTIA method (r = 0.953, P < 0.001). A Bland-Altman plot suggested no systematic error between ZNS concentrations quantified by HPLC and LTIA methods. CONCLUSION: This study confirmed no differences between the concentrations quantified by the HPLC and LTIA methods at both high and low concentrations, demonstrating the confidence of measurement by the LTIA method.

Diagnosis of bacterial meningitis in Ghana: Polymerase chain reaction versus latex agglutination methods.

Bacterial meningitis is a public health crisis in the northern part of Ghana, where it contributes to very high mortality and morbidity rates. Early detection of the causative organism will lead to better management and effective treatment. Our aim was to evaluate the diagnostic accuracy of Pastorex and Wellcogen latex agglutination tests for the detection of bacterial meningitis in a resource-limited setting. CSF samples from 330 suspected meningitis patients within the northern zone of Ghana were analysed for bacterial agents at the zonal Public Health Reference Laboratory in Tamale using polymerase chain reaction (PCR) and two latex agglutination test kits; Pastorex and Wellcogen. The overall positivity rate of samples tested for bacterial meningitis was 46.4%. Streptococcus pneumoniae was the most common cause of bacterial meningitis within the sub-region, with positivity rate of 25.2%, 28.2% and 28.8% when diagnosed using Wellcogen, Pastorex and PCR respectively. The Pastorex method was 97.4% sensitive while the Wellcogen technique was 87.6% sensitive. Both techniques however produced the same specificity of 99.4%. Our study revealed that the Pastorex method has a better diagnostic value for bacterial meningitis than the Wellcogen method and should be the method of choice in the absence of PCR.

Evaluation of new algorithm using TPLA as an initial syphilis screening test.

We retrospectively compared the performance of an existing syphilis diagnostic algorithm with a new algorithm that analyzes the results of Treponema pallidum latex agglutination (TPLA) tests. Of the 100 clinical blood samples, 51 were classified as positive through both Mediace TPLA and ESPLINE TP; 2/51 were classified as negative by Architect Syphilis TP, whereas 1/51 was negative as per LUMIPULSE Presto TP. The false positive rate when the results of Mediace TPLA and ESPLINE TP were combined was 1.96% versus 0% for both Architect Syphilis TP and LUMIPULSE Presto TP. The sensitivity of Mediace TPLA (98%) was comparable to that of Architect Syphilis TP (98%) but lower than that of LUMIPULSE Presto TP (100%). The specificity of Mediace TPLA was 98.0% versus 100% for Architect Syphilis TP, and versus 100% for LUMIPULSE Presto TP. We conclude that the performance of Mediace TPLA in combination with a reverse algorithm is nearly equal to that of enzyme immunoassay (EIA) or chemiluminescence immunoassay (CIA). Because TPLA is low cost, highly sensitive method for IgM detection, and is easy to operate, we have recommended its adoption for initial syphilis screening tests.

Evaluation of hetero-multivalent lectin binding using a turbidity-based emulsion agglutination assay.

Lectin hetero-multivalency, binding to two or more different types of ligands, has been demonstrated to play a role in case of both LecA (a Pseudomonas aeruginosa adhesin) and Cholera Toxin subunit B (a Vibrio cholerae toxin). In order to screen the ligand candidates that involve in hetero-multivalent binding from large molecular libraries, we present a turbidity-based emulsion agglutination (TEA) assay that can be conducted in a high-throughput format using the standard laboratory instruments and reagents. The benefit of this assay is that it relies on the use of emulsions that can be formed using ultrasonication, minimizing the bottleneck of substrate surface functionalization. By measuring the change in turbidity, we could quantify the lectin-induced aggregation rate of oil droplets to determine the relative binding strength between different ligand combinations. The TEA results are consistent with our prior binding results using a nanocube sensor. The developed TEA assay can serve as a high-throughput and customizable tool to screen the potential ligands involved in hetero-multivalent binding.

Antigen Detection in Urine for Noninvasive Diagnosis and Treatment Monitoring of Visceral Leishmaniasis in Human Immunodeficiency Virus Coinfected Patients: An Exploratory Analysis from Ethiopia.

Diagnosis of visceral leishmaniasis (VL) and assessment of treatment response in human immunodeficiency virus (HIV)-coinfected patients still relies on invasive tissue aspiration. This hampers scale-up and decentralization of care in resource-limited settings. Noninvasive diagnostics are urgently needed. KATEX is a frequently used latex agglutination test for Leishmania antigen in urine that has never been evaluated in HIV-coinfected individuals from Leishmania donovani-endemic areas. This was an exploratory sub-study embedded within the screening phase of a trial in highly endemic northwestern Ethiopia. All patients were HIV-positive and aspirate-confirmed VL cases. We assessed diagnostic accuracy of KATEX for VL diagnosis and as test of cure at end of treatment, using tissue aspirate parasite load as reference methods. We also described the evolution of weekly antigen levels during treatment. Most of the 87 included patients were male (84, 97%), young (median age 31 years), and had poor immune status (median cluster of differentiation type 4 count 56 cells/µL). KATEX had moderate sensitivity (84%) for VL diagnosis. KATEX had moderate sensitivity (82%) and a moderate negative predictive value (87%) but only low specificity (49%) and a low positive predictive value (40%) for the assessment of treatment outcomes. Weekly antigen levels showed characteristic patterns during treatment of patients with different initial parasite loads and treatment outcomes. Antigen detection in urine using KATEX can contribute to improved VL diagnosis in HIV-coinfected patients but has limited use for monitoring of treatment response. Better noninvasive diagnostics are needed to reduce reliance on invasive methods and thus to expand and improve clinical care for VL in resource-limited settings.

Método de aglutinación en látex para el diagnóstico rápido del síndrome de Guillain-Barré / Latex agglutination method for fast Guillain-Barré syndromes diagnosis

El síndrome de Guillain-Barré es una polirradiculoneuropatía aguda, en la cual está involucrado un componente autoinmunitario, posterior a un proceso infeccioso en pacientes no vacunados o vacunados. A partir de la aparición del virus del dengue y del Zika en el continente americano es de esperar que exista una mayor probabilidad de encontrar pacientes con este síndrome post-infeccioso. Por tanto, poder contar con un método diagnóstico rápido pudiera ser de utilidad en los centros de asistencia que reciben casos de urgencias. Se procede a modificar un método para cuantificar albuminuria por aglutinación con partículas de látex sensibilizados, para la detección de este analito en el líquido cefalorraquídeo de aquellos pacientes con sospecha de esta enfermedad. Se comprueba que el método puede ser utilizado como método de diagnóstico rápido del síndrome de Guillain-Barré(AU)

Guillain-Barré Syndrome is an acute poliradiculoneuropathy with an autoimmune component, subsequent to an infectious process in vaccinated or non-vaccinated patients. From the spreading of dengue and Zika infections in the American continent it is expected a greater probability of finding patients with this post-infectious syndrome. Therefore, a rapid diagnostic test could be useful in emergency assistance centers. A quantitative latex agglutination test to detect albuminuria was modified to be used in cerebrospinal fluid of patients with presumptive diagnosis of this disease. It has been proved that the developed test can be used for diagnostic rapid of Guillain-Barré syndrome(AU)

Epidemiology, clinical profile and role of rapid tests in the diagnosis of acute bacterial meningitis in children (aged 1-59 months).

OBJECTIVES: To study the epidemiology, clinical profile, and the role of rapid tests in the diagnosis of acute bacterial meningitis (ABM) in children (1-59 months). MATERIALS AND METHODS: A total of 250 cerebrospinal fluid (CSF) and 187 blood samples received from clinically suspected cases of ABM were processed based on standard microbiological protocols. CSF samples were also subjected to antigen and nucleic acid detection. Antibiotic susceptibility testing was done according to the Clinical Laboratory Standards Institute guidelines. Children were also evaluated for outcomes and were followed up until 6 months after discharge. RESULTS: Eighty one cases were reported to be having clinically confirmed ABM, out of which group B Streptococcus was the most common pathogen detected in 49.3% (40) patients followed by Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae type b, Escherichia coli, Klebsiella pneumoniae, and Neisseria meningitidis ACYW135 in 23.4% (19), 7.4% (6), 6.1% (5), 6.1% (5), 6.1% (5), and in 1.2% (1) patients, respectively. Complications were observed in 54.3% of the children. A follow-up of 6 months after discharge was possible in 39.5% (32) patients among whom sequelae were recorded in 93.7% (30) patients. CONCLUSION: ABM remains a major cause of neurological sequelae worldwide. Although culture is the gold standard test for its detection, the investigation takes a longer time and the results are influenced by prior antimicrobial therapy. In such cases, rapid tests aid in the early diagnosis of ABM for instituting appropriate management.

Development and Evaluation of a Latex Agglutination Test for the Identification of Francisella tularensis Subspecies Pathogenic for Human.

Francisella tularensis are highly infectious bacteria causing a zoonotic disease called tularemia. Identification of this bacterium is based on antigen detection or PCR. The paper presents a latex agglutination test (LAT) for rapid identification of clinically relevant F. tularensis subspecies. The test can be performed within three minutes with live or inactivated bacteria. The possibility to test the inactivated samples reduces the risk of laboratory acquired infection and allows performing the test under BSL-2 conditions.

Diagnostic Accuracy of Latex Agglutination Turbidimetric Immunoassay in Screening Adolescents for Helicobacter pylori Infection in Japan.

BACKGROUND/AIMS: Serologic tests are commonly used for screening Helicobacter pylori infection because they not only provide quick results but also are inexpensive. A new latex agglutination serum antibody assay (LZ test) has been developed and it is expected to be as effective as conventional assays. This study aimed to calculate a reliable cutoff value for the LZ test and to estimate the sensitivity and specificity of the cutoff value in screening adolescents for H. pylori infection in Japan. METHODS: We screened junior high school students in Akita Prefecture, Japan, for H. pylori infection. We used the data of 213 such students who underwent H. pylori stool antigen (HpSA) tests in 2016. The students who had positive results with HpSA tests were diagnosed with H. pylori infection. Of the 213 students, 209 underwent the LZ test. RESULTS: The prevalence rate of H. pylori infection was 3.8% (8/209). The area under the curve for the LZ test was 0.88. The cutoff value of the LZ test was determined to be 3.1 U/mL. At this value, the sensitivity and specificity were 87.5 and 91.5%, respectively. CONCLUSION: The accuracy of the LZ test in adolescents was well balanced for sensitivity and specificity as well as for tolerable results.

Secondary Syphilis with Tonsillar and Cervical Lymphadenopathy and a Pulmonary Lesion Mimicking Malignant Lymphoma.

BACKGROUND Syphilis is a sexually transmitted disease caused by the pathogen Treponema pallidum. Prevalence continues to rise, especially among men who have sex with men (MSM). Due to changes in patterns of sexual activity, manifestations of the disease are highly variable. CASE REPORT A 27-year-old male visited the hospital for a low-grade fever and tender 5-cm mass in the right side of his neck. His right tonsil was swollen and covered with a white coating. Levofloxacin was prescribed, but ineffective. The patient's levels of liver function enzymes increased gradually. Systemic magnetic resonance imaging (MRI) revealed bilateral cervical lymphadenopathy with right predominance, a right pulmonary nodule, and a periportal lymph node, suggestive of malignant lymphoma. However, a biopsy of the right cervical lymph node showed nonspecific inflammation. Preoperative rapid plasma reagin (RPR) and T. pallidum latex agglutination (TPLA) tests were positive. The patient was MSM and reported oral sex with many sexual partners. A diagnosis of secondary syphilis was made. Oral amoxicillin was effective, and all symptoms other than periportal lymph node resolved. CONCLUSIONS Tonsillitis, cervical lymphadenopathy, and lung lesions can be manifestations of secondary syphilis. A detailed history, pathology, and serology are crucial for diagnosis.

Diagnostic accuracy of urinary latex agglutination test (KAtex) for the diagnosis of visceral leishmaniasis: A meta-analysis.

Latex agglutination test (KAtex) has been used in the last two decades for the diagnosis of visceral leishmaniasis (VL) in different VL-endemic areas. Here, we present a meta-analysis of studies which evaluated the KAtex for the diagnosis of VL to find out its overall diagnostic performance. A database search was performed on PubMed, Scopus, ISI Web of Science, Iranmedex and Google Scholar. The search of databases found 57 papers, of which 17 articles fulfilled our eligibility criteria. Meta-analysis of diagnostic accuracy (MADA) and Hierarchical Summary Receiver Operating Curve (HSROC) packages were used to do the meta-analysis and to obtain pooled estimates of sensitivity and specificity. Fixed effect bivariate analysis was conducted, using Mantel-Haenszel estimator, to measure the performance and diagnosis odds ratio (DOR) of the test. Heterogeneity of the test results was assessed by Chi-squared test. The sensitivity of individual studies ranged from 39.8 to 100%, and the specificity ranged from 64 to100%. The combined sensitivity and specificity estimates of KAtex were 77% (95% CI, 70-83%), and 97% (95% CI, 93-97%), respectively. Comparing the performance of the test by region suggests a significant difference where the lowest and highest sensitivities are reported from Nepal/Tunisia and Europe/Middle East respectively (p < 0.05). On the other hand, the lowest and highest rates of specificity were reported from Sudan and America/Middle East respectively. The overall specificity of KAtex is satisfactory. However, KAtex suffers from low sensitivity and this shortcoming should be improved. The test provides a rapid and simple diagnosis of VL and improvement of its sensitivity deserve further studies.