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

Sarfaraz Ahmad Ejazi,Md Asjad Karim Bakhteyar,Pradeep Das,Rama Prosad Goswami,Pradyot Bhattacharya,Nahid Ali,Aquil Ahmad Mumtaz,Krishna Pandey,Mehebubar Rahaman,Vidya Nand Ravi Das

doi:10.1371/journal.pntd.0005035

Abstract

BackgroundVisceral 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 findingsWe 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/significanceELISA 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.

Highlights

Visceral Leishmaniasis (VL) is a vector-borne fatal infectious disease disseminated in 88 countries of the world, in remote areas of India, Bangladesh, Sudan, Brazil, Ethiopia and South Sudan where 90% of the cases occur [1]
Post kala-azar dermal leishmaniasis (PKDL) is a skin disease which occurs after treatment as a sequel to VL
Available immunochromatographic rapid diagnostic test such as rK39-RDT is used for field diagnosis of VL, detects antibodies in serum samples

Summary

Introduction

Visceral Leishmaniasis (VL) is a vector-borne fatal infectious disease disseminated in 88 countries of the world, in remote areas of India, Bangladesh, Sudan, Brazil, Ethiopia and South Sudan where 90% of the cases occur [1]. Antigen rk (39 amino acid kinesin-related protein) based RDTs are the most commonly used rapid test for sero-diagnosis of VL, especially in the Indian subcontinent where it gave sensitivity and specificity estimates of 97% and 90.2%, respectively [7]. Their diagnostic performance varies from moderate in Latin America to even low in East African region [8]. Diagnostic tests available for VL such as tissue aspiration are invasive and painful they are capable of evaluating the treatment response. Serological tests less invasive than tissue aspiration are incompetent to assess cure. A noninvasive test with acceptable sensitivity and competency, to decide cure would be an asset in disease management and control

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