Evaluation of urine sample for diagnosis of visceral leishmaniasis using rK-39 immunochromatographic test in Northwest Ethiopia

BACKGROUND

Visceral leishmaniasis is the most severe form of leishmaniasis which ranks second in mortality and fourth in morbidity. Parasitological diagnostic techniques with splenic aspirate remain the gold standard. However, sample collection is risky, painful, and difficult. Alternatively, serological techniques provide good diagnostic accuracy using serum sample that is difficult for applying on small children and in the field. So, finding alternative non-invasive and self-collected samples like urine is very important. Thus, the study aimed to evaluate the diagnostic performance of the rK-39 strip test using urine for diagnosis of visceral leishmaniasis.

METHODS

A multicenter institutional-based cross-sectional study was conducted from November 2019 to March 2021 at Northwest Ethiopia. Sociodemographic information was collected using a structured questionnaire. Blood sample and midstream urine sample were collected for rK-39 test. Data were entered into Epi-data version 4.2 and analyzed using SPSS version 24.0. Diagnostic performance parameters of urine-based rK-39 rapid test, i.e. sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios (LR+/-), and diagnostic accuracy were determined on contingency table by using serum-based rK-39 test result as a reference. An agreement between urine and serum-based rK-39 test was statistically determined by kappa value.

RESULT

In total, 300 subjects, age ranged between 7 and 60 years, were included in the study. The overall sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of urine-based rK-39 test were found to be 98.0% (95% CI: 93.0% - 99.8%), 95.5% (95% CI: 91.6% - 97.9%), 91.6% (95% CI: 85.2%- 95.4%), 98.9 (95% CI: 96.0%- 99.7%), and 96.33% (95% CI: 93.53-98.16%), respectively. Additionally, there was a strong agreement between the results obtained on rK-39 ICT using urine and serum samples (kappa = 0.92; P < 0.001).

CONCLUSION

Urine-based rK-39 ICT had an excellent high sensitivity, specificity and strong agreement with serum-based rK-39 ICT results. This indicates that urine sample would be a promising noninvasive and easy to collect sample for diagnosis of VL in field and rural settings.

Isolation and characterisation of Leishmania donovani protein antigens from urine of visceral leishmaniasis patients

Diagnosis of visceral leishmaniasis (VL) relies on invasive and risky aspirate procedures, and confirmation of cure after treatment is unreliable. Detection of Leishmania donovani antigens in urine has the potential to provide both a non-invasive diagnostic and a test of cure. We searched for L. donovani antigens in urine of VL patients from India and Sudan to contribute to the development of urine antigen capture immunoassays. VL urine samples were incubated with immobilised anti-L. donovani polyclonal antibodies and captured material was eluted. Sudanese eluted material and concentrated VL urine were analysed by western blot. Immunocaptured and immunoreactive material from Indian and Sudanese urine was submitted to mass spectrometry for protein identification. We identified six L. donovani proteins from VL urine. Named proteins were 40S ribosomal protein S9, kinases, and others were hypothetical. Thirty-three epitope regions were predicted with high specificity in the 6 proteins. Of these, 20 were highly specific to Leishmania spp. and are highly suitable for raising antibodies for the subsequent development of an antigen capture assay. We present all the identified proteins and analysed epitope regions in full so that they may contribute to the development of non-invasive immunoassays for this deadly disease.

Noninvasive Sweat-Based Diagnosis of Visceral Leishmaniasis and Post Kala-Azar Dermal Leishmaniasis

The diagnosis of visceral leishmaniasis (VL) is one of the foremost barriers in the control of this disease, as demonstration of the parasite by splenic/bone marrow aspiration is relatively difficult and requires expertise and laboratory support. The aim of the present study was to find a noninvasive diagnostic approach using the existing recombinant kinesine-39 (rK-39) immunochromatographic nitrocellulose strips test (ICT) with a human sweat specimen for the diagnosis of VL. The investigation was carried out on specimens (blood, sweat, and urine) collected from 58 confirmed VL, 50 confirmed post kala-azar dermal leishmaniasis (PKDL), 36 healthy control, and 35 patients from other diseases. The data obtained from this study reveal that 96.6% clinically confirmed active VL participants were found to be positive when tested against a sweat specimen. Interestingly, the scenario was similar when tested against a blood specimen (96.6% positive by rK-39). Moreover, a test of both sweats and blood specimens from 50 PKDL participants resulted in 100% positivity, whereas no healthy control participants were found to be rK-39 positive. The sensitivity of the rK-39 ICT in sweat specimen was 94.7%, whereas the specificity was 100% in healthy controls from endemic, nonendemic, and other infectious diseases, respectively. No difference was observed in sweat specimen of VL and PKDL cases which signifies its reliability. However, further evaluation of this method on a larger scale could enhance the reliability of the proposed model so that it could be used efficiently in VL management and eradication.

Noninvasive Diagnosis of Visceral Leishmaniasis: Development and Evaluation of Two Urine-Based Immunoassays for Detection of Leishmania donovani Infection in India

Background

Visceral Leishmaniasis (VL), a severe parasitic disease, could be fatal if diagnosis and treatment is delayed. Post kala-azar dermal leishmaniasis (PKDL), a skin related outcome, is a potential reservoir for the spread of VL. Diagnostic tests available for VL such as tissue aspiration are invasive and painful although they are capable of evaluating the treatment response. Serological tests although less invasive than tissue aspiration are incompetent to assess cure. Parasitological examination of slit-skin smear along with the clinical symptoms is routinely used for diagnosis of PKDL. Therefore, a noninvasive test with acceptable sensitivity and competency, additionally, to decide cure would be an asset in disease management and control.

Methodology/principal findings

We describe here, the development of antibody-capture ELISA and field adaptable dipstick test as noninvasive diagnostic tools for VL and PKDL and as a test of cure in VL treatment. Sensitivity and specificity of urine-ELISA were 97.94% (95/97) and 100% (75/75) respectively, for VL. Importantly, dipstick test demonstrated 100% sensitivity (97/97) and specificity (75/75) in VL diagnosis. Degree of agreement of the two methods with tissue aspiration was 98.83% (κ = 0.97) and 100% (κ = 1), for ELISA and dipstick test, respectively. Both the tests had 100% positivity for PKDL (14/14) cases. ELISA and dipstick test illustrated treatment efficacy in about 90% (16/18) VL cases when eventually turned negative after six months of treatment.

Conclusions/significance

ELISA and dipstick test found immensely effective for diagnosis of VL and PKDL through urine samples thus, may substitute the existing invasive diagnostics. Utility of these tests as indirect methods of monitoring parasite clearance can define infected versus cured. Urine-based dipstick test is simple, sensitive and above all noninvasive method that may help not only in active VL case detection but also to ascertain treatment response. It can therefore, be deployed widely for interventions in disease management of VL particularly in poor resource outskirts.

Visceral leishmaniasis (VL), one of the most prevalent parasitic diseases in the developing world causes serious health concerns. Post kala-azar dermal leishmaniasis (PKDL) is a skin disease which occurs after treatment as a sequel to VL. Parasitological diagnosis involves invasive tissue aspiration which is tedious and painful. Commercially available immunochromatographic rapid diagnostic test such as rK39-RDT is used for field diagnosis of VL, detects antibodies in serum samples. Urine sample is however, much easier in collection, storage and handling than serum and would be a better alternative where collection of tissue aspirate or blood is impractical. In this study, we have developed and evaluated the performance of two urine-based diagnostic assays, ELISA and dipstick test, and compared the results with serological rK39-RDT. Our study shows the capability of urine-based tests in detecting anti-Leishmania antibodies effectively for both VL and PKDL diagnosis. The ability of dipstick test to demonstrate negative results after six months in 90% of the VL cases after treatment could be useful as a test of clinical cure. Urine-based tests can therefore replace the need for invasive practices and ensure better diagnosis under filed settings.

Urinary C reactive protein levels in dogs with leishmaniasis at different stages of renal damage

The objectives of the study were to validate a time-resolved immunofluorometric assay for C reactive protein (CRP) quantification in urine of dogs and to investigate the influence that the presence of proteinuria and azotemia could have on serum and urinary CRP (uCRP) values in dogs with leishmaniasis. Samples obtained from dogs naturally infected with Leishmania infantum were classified into four groups on the basis of the results of urinary protein/creatinine ratio and serum creatinine (sCr). In addition, 7 dogs were monitored at initial diagnosis and after a follow up visit. The assay showed good analytical performance based on precision, accuracy and limit of detection results. Results of the study suggested that CRP is present in urine of dogs with leishmaniasis and renal damage since uCRP/creatinine ratio was significantly increased in dogs with proteinuria, being the highest values observed in dogs with proteinuria and elevated sCr, and that the measurement of uCRP could be a tool to detect and evaluate the possible kidney damage associated with this disease.

Evaluation of rk39 immunochromatographic test with urine for diagnosis of visceral leishmaniasis

This study evaluates commercially available rK39 immunochromatographic strips using urine for diagnosis of visceral leishmaniasis (VL). Freshly collected urine and serum samples of 280 parasitologically confirmed VL patients and 66 endemic healthy controls (EHC), 48 nonendemic healthy controls (NEHC) and 45 different diseases were tested with rK39 strips. The sensitivity of rK39 in urine was 96.4% while the specificity was low varying from 66.7% in EHC, 77.08% in NEHC to 62.2% in different diseases. With serum, sensitivity was 100% whereas the specificity was 100%, 92.4% and 95.55% for the respective control groups. In the present format, the immunochromatographic strips cannot be used for the diagnosis of VL using urine samples.

Evaluation of latex agglutination test (KAtex) for early diagnosis of kala-azar

Kala-azar is one of the major public health problem in Bangladesh. But the diagnosis of the problem often is difficult, unusual and time consuming, a simple, noninvasive, easy to perform, reliable and rapid diagnostic test has been a long-felt need of the clinicians. Therefore, the present study was conducted to see the sensitivity and specificity of Latex Agglutination test (KAtex) to detect leishmanial antigen from urine of kala-azar cases. The study was carried out in the department of Paediatrics, Mymensingh Medical College and Hospital, Bangladesh during July to December, 2008. A total of 100 urine samples were collected of which 50 were confirmed kala-azar cases and 50 were age and sex matched controls. Out of 50 kala-azar cases 47 showed positive result of KAtex. The test was also positive in 01 out of 30 healthy controls. None of the febrile controls was positive by KAtex. The sensitivity, specificity, positive predictive value and negative predictive value of the test using presence of LD bodies in splenic and/or bone marrow aspirate as gold standard were 94%, 98%, 97.91% and 94.23% respectively. KAtex is simple, noninvasive, easy to perform, rapid and reliable test for diagnosing kala-azar in endemic area and useful for small, less equipped laboratories as well as for the laboratories with better facilities.

In search of an ideal test for diagnosis and prognosis of kala-azar

The latex agglutination test (KAtex), direct agglutination test (DAT), and the rK39 immuno-chromatographic strip test (dipstick test) were evaluated for their role in the diagnosis and prognosis of visceral leishmaniasis (kala-azar) in India. Sera and urine samples from 455 subjects--150 confirmed visceral leishmaniasis cases, 160 endemic controls, 100 non-endemic controls, and 45 other febrile diseases--were included in the study. The sensitivity of the KAtex, DAT, and rK39 strip test was 87% [95% confidence interval (CI) 80-96], 93.3% (95% CI 88-100), and 98% (95% CI 93-100) respectively. The specificity of these tests was 98% (95% CI 93-100), 93% (95% CI 87-100), and 89% (95% CI 82-97) for the KAtex, DAT, and rK39 strip test respectively. Fifty cases were followed up and subjected to the KAtex, DAT, and rK39 strip test after 30 days of successful treatment. The DAT and rK39 strip test showed positive results in all the 50 cases whereas the KAtex showed no positive reaction in any case. Based on the results, it is concluded that the sensitivity and specificity of the DAT and rK39 strip test are comparable but the greater convenience of use of the strip test makes it a better tool for the diagnosis of visceral leishmaniasis in the peripheral areas of endemic regions whereas the sensitivity of the KAtex needs to be improved to promote its use as a first-line diagnostic test in the field-setting. It may be used for the prognosis of the disease as antigen becomes undetectable in urine after 30 days of the completion of the treatment. Alternatively, it can be used as an adjunct with rK39 for sero-epidemiological surveys.

Performance of latex agglutination test (KAtex) in diagnosis of visceral leishmaniasis in Iran

BACKGROUND

Visceral leishmaniasis (VL) is an endemic disease in some parts of Iran. Many techniques have been used for diagnosis of VL, among which the urine based latex agglutination test (KAtex) is a promising one.

OBJECTIVE

To compare three diagnostic tests of VL including KAtex, ELISA and Direct Agglutination Test (DAT) in VL patients and healthy controls in the south west of Iran.

METHODS

Serum (n = 29) and urine samples (n = 31) were collected from parasitologically confirmed VL patients. Control samples were obtained from healthy individuals (n = 61) and also from patients with infectious diseases other than VL. The collected serum samples were tested by DAT and ELISA using crude antigen from promastigotes of Leishmania infantum and the urine samples were tested by KAtex.

RESULTS

Sensitivity and specificity of KAtex for diagnosis of VL was found to be 83.9% and 100%, respectively. Sensitivities of DAT and ELISA were 93.1% and 86.2% and their specificities were 100% and 90.5%, respectively.

CONCLUSION

KAtex yielded a satisfactory sensitivity and specificity in diagnosis of VL in Iran and can be recommended as a rapid, field applicable and reliable test for diagnosis of VL in this region.

A comparative study of antigen and antibody detection in visceral leishmaniasis using serum and urine-based ELISA

An antigen-based ELISA system was evaluated for diagnosis of visceral leishmaniasis (VL). Urine samples from confirmed VL cases were tested by the system in comparison with urine samples from patients with non-VL infectious disease and patients with non-infectious diseases. Antigen was detected in urine of 21 out of 35 (60%) of VL cases. No cross reaction was found with samples from healthy individuals except in 3 samples from non-VL infectious diseases. Two samples from cutaneous leishmaniasis patient and one from patient with toxoplasmosis. The results obtained with the antigen-based ELISA were compared to those obtained with direct agglutination test (DAT), an antibody-based ELISA and indirect immunofluorescent antibody (IFA) revealed that the antigen-based ELISA is comparable in terms of specificity (91.2%; 95% CI=75.2-97.7%) but with a lower sensitivity (60%; 95% CI=42.2-75.6%). These results suggest that the antigen detection in urine by the noninvasive antigen-based ELISA system might offer a useful method for diagnosis of VL.

Leishmania infantum DNA detection in urine from patients with visceral leishmaniasis and after treatment control

A urine-polymerase chain reaction (PCR) assay was validated for diagnosis of human visceral leishmaniasis (VL), taking advantage of the accessibility of urine samples. Leishmania infantum DNA presence was examined in 17 urine samples from 17 patients with VL during a clinical episode and in 55 urine samples from 17 patients with VL monitored after treatment at different intervals. Fifty-nine urine samples from 59 controls with no history of VL were also studied. The urine-PCR test was positive in 15/17 samples obtained during the episode (sensitivity, 88%). None of the controls tested were urine-PCR positive (specificity, 100%). During the monitoring period, 25% of the samples gave a positive urine-PCR. Results were compared with other diagnostic methods, such as urine antigen detection and peripheral blood-PCR and culture, with good concordance during the clinical episode and differences in the follow-up period. This study suggests that urine-PCR is sensitive for diagnosis and may be useful to monitor treatment efficacy.

Antigen detection from urine of Kala-azar cases by latex agglutination test

A recently developed Latex agglutination method known as "KATEX" for detecting leishmanial antigen in urine of Kala-azar patients was evaluated on 97 Kala-azar cases and 35 controls in the department of Microbiology, Mymensingh Medical College during the period from March' 2004 to February' 2005. The method yielded sensitivity as 100% and 82.8% in 33 confirmed and 64 ICT positive cases respectively. Since 8.6% controls showed antigen positive results, so specificity of KATEX was calculated as 91.4%. KATEX methods for antigen detection in urine should be used as an early immuno-diagnostic test as it has yielded high sensitivity. But interpretation of a positive test must be made cautiously having correlation with clinical findings as because it becomes false positive in Kala-azar free person. Further elucidation of KATEX method including larger population from community giving particular emphasis on its prognostic use was strongly recommended.

Evaluation of renal function in human visceral leishmaniasis (kala-azar): a prospective study on 50 patients from Brazil

BACKGROUND

There are few studies of renal function evaluation in visceral leishmaniasis (kala-azar). The aim of this study was to evaluate glomerular filtration rate (GFR) and tubular function as urinary acidification capacity and maximal urinary concentration, in patients with the chronic form of kala-azar.

PATIENTS AND METHODS

This is a cross-sectional study of 50 consecutive patients with kala-azar. GFR was calculated by 24-hour creatinine clearance. Urinary pH, titratable acidity and urinary ammonia excretion were measured after acid-loading with NH4Cl. Urine to plasma osmolality ratio (U/Posm) was evaluated after water withdrawal and vasopressin administration. All parameters were also measured in 20 healthy volunteers (control group).

RESULTS

GFR was normal in 44% of the patients, elevated in one third, and decreased in the remaining 28%. Decreased GFR was attributed to fluid loss, hypotension and immunological glomerular disease. Urinary concentrating capacity was abnormal in 68% of the patients with kala-azar after pitressin administration. A urinary pH higher than 5.5 was seen in 64% of cases after ammonium chloride acidification test. There was decreased formation of titratable acidity in 64% and low formation of ammonia urinary excretion in 30% of cases. Complete distal renal tubular acidosis was observed in 30% of patients and an incomplete form was found in 34%.

CONCLUSION

Abnormalities in glomerular filtration, urinary concentration and acidification are consistently associated to the chronic form of kala-azar and can be a consequence of the immunological system dysregulation that occurs in this disease.

Detection of Leishmania infantum DNA by fret-based real-time PCR in urine from dogs with natural clinical leishmaniosis

The aim of this study was to detect Leishmania infantum DNA by real-time PCR in urine from different groups of dogs with clinical leishmaniosis. Urine from 10 clinically healthy dogs and 43 dogs with clinical leishmaniosis diagnosed by positive serology and/or bone marrow PCR were studied. The group of 43 dogs with clinical leishmaniosis was divided into three subgroups: 13 dogs with renal insufficiency and proteinuria (urine protein-creatinine ratio greater than one), 13 dogs with only proteinuria, and 17 dogs with neither renal insufficiency nor proteinuria. The detection of Leishmania DNA was performed by light cycler real-time PCR using hybridization probes in each urine sample. Leishmania positive PCR was found in 47% (20/43) of the urine from leishmaniotic dogs, while all urine from clinically healthy dogs were negative. The percentages of positive Leishmania PCR were 85% (11/13) in dogs with renal insufficiency and proteinuria, 23% (3/13) in dogs with proteinuria and 35% (6/17) in dogs with neither renal insufficiency nor proteinuria. Dogs with renal insufficiency and proteinuria presented a statistical significant greater percentage of positive Leishmania PCR in urine when compared with the other subgroups (P<0.02). This study demonstrates the presence of Leishmania DNA in urine of dogs with leishmaniosis. Those dogs with severe renal damage present a greater number of Leishmania parasites in urine.

Evaluation of a latex agglutination test (KAtex) for detection of Leishmania antigen in urine of patients with HIV-Leishmania coinfection: value in diagnosis and post-treatment follow-up

The usefulness of antigen detection in urine as an alternative tool for diagnosis of leishmaniasis and post-treatment follow-up in patients with Leishmania-HIV coinfection was evaluated with a latex agglutination test (KAtex; Kalon Biological, UK). Forty-nine HIV-infected patients with visceral leishmaniasis were included in the study. Antigen detection in urine (ADU) was positive in 42 of 49 (sensitivity, 85.7%) samples obtained during a primary episode. After treatment, a follow-up study in 23 patients was performed by simultaneous ADU and culture of peripheral blood mononuclear cells in 148 determinations. The two methods gave concordant results in 94 cases, 38 of which were positive and 56 negative. In five cases, ADU was negative and culture of peripheral blood mononuclear cells was positive: two of these cases corresponded to clinical relapses. In 49 cases, culture of peripheral blood mononuclear cells was negative and ADU was positive. In the absence of clinical symptoms, the detection of parasite antigens in 71 of 130 (54.6%) urine samples was not associated with clinical disease. The Kaplan-Meier estimates of the probability of relapse at 6, 12, 18, and 24 months were 16% (95%CI, 15-17%), 20% (95%CI, 18-22%), 31% (95%CI, 27-35%), and 71% (95%CI, 52-89%), respectively, in patients with a positive ADU result. In contrast, when ADU was negative, the probability of relapse was 5% at 6 months (95%CI, 2-8%) (only 2 of 11 patients who relapsed had a negative test). ADU by KAtex is appropriate for primary diagnosis of visceral leishmaniasis, for monitoring the efficacy of treatment, and for detection of subclinical infection.

Free light-chain proteinuria and normal renal histopathology and function in 11 dogs exposed to Lleishmania infantum, Ehrlichia canis, and Bbabesia canis

The purpose of this retrospective study was to investigate the relationship among proteinuria consisting of immunoglobulin free light chains (FLCs), renal histopathologic findings, and routine markers of renal function in 11 dogs exposed to Leishmania infantum (n = 8), Ehrlichia canis (n = 2), and Babesia canis (n = 1). FLC proteinuria was suspected based on identification of a 22- to 27-kDa band by sodium dodecyl sulfate-agarose gel electrophoresis (SDS-AGE) and later confirmed by immunofixation electrophoresis. SDS-AGE identified an isolated band of 22-27 kDa in 8 dogs, whereas the remaining 3 had a 22- to 27-kDa band and an additional band of 67-72 kDa. The median urine protein-to-urine creatinine ratio was 0.37 (range, 0.11-2.24) and increased ratios were found in 6 dogs (54.5%) (reference value, <0.7). All dogs underwent histologic examination of renal percutaneous biopsy specimens and determination of serum creatinine and urea concentrations. Tissue samples for light microscopy were stained with hematoxylin-eosin, periodic acid-Schiff, Goldners trichrome, and methenamine silver. In the study group, the glomerular tufts, mesangium, tubulointerstitium, and vessels appeared unaffected. The median serum creatinine concentration in these 11 dogs was 1.3 mg/dL (range, 0.8-1.5 mg/dL; reference range, 0.6-1.5 mg/dL), whereas the concentration for urea was 28 mg/dL (range, 22-52 mg/dL; reference range, 20-50 mg/dL). All dogs had normal renal morphology and had normal serum creatinine and urea concentrations, suggesting that immunoglobulin FLC may be detected in the urine of dogs exposed to L. infantum, E. canis, and B. canis without any apparent structural or functional renal derangement.

Evaluation of a urinary antigen-based latex agglutination test in the diagnosis of kala-azar in eastern Nepal

BACKGROUND

We evaluated the diagnostic accuracy as well as the reproducibility of the urine latex agglutination test 'KAtex' in the diagnosis of kala-azar in patients recruited at a tertiary care centre in Dharan, Nepal, between November 2000 and January 2002.

METHODS

All patients presenting with fever of 2 weeks or more and splenomegaly were consecutively enrolled. Bone marrow and--if negative--spleen aspirates were examined for Leishmania donovani. Serum and urine samples were taken in duplicate for the Direct Agglutination Test (DAT) and KAtex. The reference laboratory determined sensitivity and specificity of KAtex. Reproducibility between both laboratories was assessed.

RESULTS

KAtex was performed on urine from 155 parasitologically confirmed kala-azar and 77 non-kala-azar cases (parasitology and DAT-negative). KAtex showed a sensitivity of 47.7% (74/155, 95% CI: 39.7-55.9) and a specificity of 98.7% (76/77, 95% CI: 93.0-100.0). Reproducibility of KAtex showed a kappa of 0.684 (P < 0.001, n = 232).

CONCLUSION

KAtex evaluation showed high specificity, low sensitivity and moderate reproducibility. A urine test for kala-azar could become a real breakthrough in kala-azar management if its reproducibility and sensitivity could be further improved.

Direct agglutination test with urine samples for the diagnosis of visceral leishmaniasis

A new direct agglutination test (DAT) for use with urine samples for the diagnosis of visceral leishmaniasis (VL) has been developed and compared with the conventional DAT with serum samples and our previously reported enzyme-linked immunosorbent assay (ELISA) with urine samples (urine ELISA). The new DAT, in which anti-human IgG was used as enhancing antibody, was tested with urine samples from 75 VL patients and 225 non-VL patients and healthy people. The sensitivity of the new DAT (90.7%), was almost the same as that of the conventional DAT (91.0%) and the urine ELISA (93.3%). The specificity of the new DAT (96.4%) was nearly identical with that of the urine ELISA (97.3%). A urine-based DAT has several advantages over the conventional DAT: sample collection is non-invasive and it can process larger numbers of samples with smaller amounts of antigen.

Field evaluation of latex agglutination test for detecting urinary antigens in visceral leishmaniasis in Sudan

A latex agglutination test to detect urinary antigens for visceral leishmaniasis (VL) was studied. In 204 patients with suspected VL, KAtex had a sensitivity of 95.2% with good agreement with microscopy smears but poor agreement with 4 different serology tests. It was also positive in 2 confirmed VL cases co-infected with HIV. In all K4tex-positive confirmed cases actively followed up after treatment, the test became negative 1 month after completion of treatment. While IC4tex had a specificity of 100% in healthy endemic and non-endemic controls, the direct agglutination test (DAT) was positive in 14% of the KAtex-negative healthy endemic controls. KAtex is a simple addition to the diagnostics of VL particularly at field level and as a complementary test for the diagnosis of VL in smear-negative cases with positive DAT results.

Diagnosis of visceral leishmaniasis by enzyme-linked immunosorbent assay using urine samples

A diagnostic method has been developed to detect anti-Leishmania donovani immunoglobulin G (IgG) in urine by enzyme-linked immunosorbent assay (ELISA). In measuring anti-L. donovani IgG, IgA, and IgM in urine, the method performed best in the detection of IgG. The sensitivity and specificity of the assay were determined with panels of urine samples from 62 visceral leishmaniasis (VL) patients, 59 healthy controls from areas of endemicity, 53 healthy controls from areas of nonendemicity, 59 malaria patients, 13 tuberculosis patients, 23 cutaneous leishmaniasis patients, and 7 patients with other diseases. Using L. donovani promastigote crude antigen, the test had 93.5% sensitivity (58 positives of 62 VL patient samples) and 89.3% specificity (191 negatives of 214 non-VL patient samples). The ELISA with acetone-treated L. donovani promastigote antigen raised the sensitivity and specificity to 95.0 and 95.3%, respectively. Western blot analysis revealed that most of the samples that cross-reacted with crude antigen in ELISA did not recognize any antigenic component of L. donovani crude antigen. We also checked 40 serum samples from the same group of VL patients for anti-L. donovani IgG and got 90.0% sensitivity with both crude and acetone-treated antigens. As collection of urine is much easier than collection of serum, the detection of anti-L. donovani IgG in urine with acetone-treated antigen will be useful in epidemiological studies. It could be an adjunct of laboratory diagnosis.

Antigenuria in visceral leishmaniasis: detection and partial characterisation of a carbohydrate antigen

The detection of antigen in the urine is increasingly being used for diagnosis of parasitic infections. A urinary antigen has recently been demonstrated in visceral leishmaniasis (VL), using a latex agglutination test. The results of our study show that the detected antigen is: heat-stable, precipitates with acetone and ethanol but not TCA, is sensitive to periodate and acid hydrolysis but not to pronase E, lipase, or neuraminidase. The antigen is a low molecular weight glycoconjugate that can be extracted by phenol-water, partitions into the aqueous phase when extracted with Triton X-114 or chloroform/methanol, and can be labelled by biotin hydrazide. Since this urinary antigen cannot be characterised by conventional SDS-PAGE and Western blotting, we used an affinity transfer blotting system in which antigens were captured onto nitro-cellulose paper previously coated with a specific antibody. Using this system a low molecular weight antigen (LMWA) spanning an area of the nitro-cellulose membrane corresponding to molecular weight of 5-20 kDa was detected in the urine of VL patients (from Nepal, Sudan, Brazil, Yemen and Spain) and of experimentally infected animals. No LMWA was detected in the urine of patients with malaria, schistosomiasis, or other nonparasitic diseases including typhoid and brucellosis. Immunoprecipitation, using antibody-coated latex, followed by immunoblotting showed that the LMWA is the target antigen in the previously described latex agglutination test ('KATEX'). The antigen is detectable in both the promastigote and amastigote stages of the parasite. Monoclonal antibodies (mAbs) against Leishmania glycoconjugates strongly react with this molecule. These results suggest that the detected antigen is highly specific and diagnostic for VL.

Latex agglutination test for the detection of urinary antigens in visceral leishmaniasis

This paper describes a new latex agglutination test ('KATEX') for the detection of leishmanial antigen in the urine of patients with visceral leishmaniasis. In preliminary laboratory trials, using urine collected from well-defined cases and controls from Brazil, Yemen and Nepal, the test had 100% specificity and a sensitivity between 68 and 100%. When used in a time-course experiment in cotton rats infected with Leishmania donovani, the test became positive 1 week after inoculation and antigen levels in urine declined rapidly after chemotherapy (the test was negative before the end of the course of treatment). Finally, in an integrated study performed in Sudan, KATEX was compared to microscopy and four different serological tests in a group of 73 patients having presented with clinical manifestations suggestive of visceral leishmaniasis. Compared to microscopy, KATEX performed better than any single serological test in predicting positivity and a particularly good result was obtained by combining KATEX and the direct agglutination test (DAT).

Antimony excretion in a patient with renal impairment during meglumine antimoniate therapy

Meglumine antimoniate was administered to a patient with visceral leishmaniasis with normal renal function. Soon after the first intramuscular administration of meglumine antimoniate 20 mg/kg, equivalent to 510 mg antimony (Sb), the patient developed septic shock with oliguria. Creatinine clearance decreased to 23 ml/minute. Treatment was discontinued, and Sb urinary excretion was measured. After the initial dose, 500.25 mg Sb was recovered in urine over 8 days, corresponding to 98% of the amount of Sb given intramuscularly (66% eliminated within first 48 hrs). Nine days after the dose, meglumine antimoniate was reintroduced at a dosage of 11.7 mg/kg (equivalent to 300 mg Sb) every 48 hours with good tolerance. At that time creatinine clearance had returned to 87.8 ml/minute. By day 14 of therapy the interval was reduced to daily administration of the same dose; the dosage was increased to 16.6 mg/kg/day (equivalent to 425 mg Sb) from day 17 to day 31. The patient eventually completely recovered and was discharged with normal renal function. Although no specific guidelines exist for dosage adjustment in renal failure, monitoring of Sb urinary excretion indicates that the kidneys are the almost exclusive route of elimination.

Short report: detection of 72-75-kD and 123-kD fractions of Leishmania antigen in urine of patients with visceral leishmaniasis

Two polypeptide fractions of 72-75 kD were detected in the urine of 14 of 15 patients with visceral leishmaniasis (VL) and another fraction of 123 kD was found in 10 of the 15 patients by using a Western blot technique. None of these fractions was detected in the urine of 20 controls. These results suggest that antigen detection in urine could be a powerful, noninvasive method for VL diagnosis.

Detection of Leishmania donovani soluble antigen and antibody in the urine of visceral leishmaniasis patients

Urine samples from 21 patients with visceral leishmaniasis were examined for the presence of Leishmania donovani soluble antigen and antibody by double counter-current immunoelectrophoresis. 19 samples revealed both antigen and antibody (IgM in 5 and IgG in all samples). 2 urine samples collected 10 and 13 days after Glucantime treatment revealed only antibody (IgG), not soluble antigen.