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

Abstract

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.

Reference Values for Leishmania Infantum Parasitemia in Different Clinical Presentations: Quantitative Polymerase Chain Reaction for Therapeutic Monitoring and Patient Follow-Up

“…Other biologic assays have been proposed for diagnosis of relapses; however, qualitative analysis of specific antibodies is dependent on the sensitivity of immunoblotting and the immune status of the host, and antigen detection in urine during patient follow-up is not correlated with clinical symptoms. 24,25 In conclusion, quantification of L. infantum DNA in blood samples showed a dispersion of the results over 9 log values and determined a threshold between asymptomatic carriage and the acute phase of the disease. Sampling blood rather than bone marrow for initial diagnosis of the disease constitutes an additional advantage and a better approach for analyzing asymptomatic carriage of Leishmania in epidemiologic and genetic studies.…”

Diagnosing visceral leishmaniasis and HIV/AIDS co-infection: a case series study in Pernambuco, Brazil

“…However, it has been reported that antigenuria becomes negative after successful chemotherapy, suggesting that KAtex may be a useful tool for monitoring the efficacy of the treatment 2 . In another two studies of co-infected patients in Spain, KAtex had a sensitivity of 85.7% and 100%, respectively, when the parasite load was high 27,34 . ATTAR et al, 5 reported the potential use of this test to diagnose active infection, although the need still exists for additional studies in order to provide a better definition of the role of KAtex, both in investigating the infection and during post-therapy follow-up.…”

“…The present report of the use of KAtex in co-infected patients is the first publication on the Brazilian population. Whether the test is applicable to detecting asymptomatic or subclinical populations has still not been sufficiently clarified 5,13,27 .…”

Comparison of New Diagnostic Tools for Management of Pediatric Mediterranean Visceral Leishmaniasis

“…Several studies have demonstrated Leishmania antigens in the urine of VL patients and animals using different techniques including double countercurrent immunoelectrophoresis (22), ELISA (3,20,36), and Western blotting (13). Recently, a latex agglutination test (KAtex kit) to detect Leishmania antigen in urine showed 100% specificity and 47 to 100% sensitivity in different studies with immunocompetent patients (2,32) and 96 to 100% specificity and 85 to 100% sensitivity in immunodepressed patients (31,37).…”