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Disease/health condition -
Neglected tropical diseases, Visceral leishmaniasis (Kala-azar)
Direct agglutination test (DAT) for visceral leishmaniasis (VL)
Assay format
Tube agglutination test
Information History
First added in 2020
Changed in 2024
Purpose type
Aid to diagnosis
Purpose
To aid in the diagnosis of clinically suspected visceral leishmaniasis (Kala-azar).
Specimen types
Serum, Dried blood spots (DBS)
WHO prequalified or recommended products
N/A
WHO supporting publications
WHO Expert Committee on the Control of the Leishmaniases & World Health Organization. (2010). Control of the leishmaniases: report of a meeting of the WHO Expert Commitee on the Control of Leishmaniases, Geneva, 22-26 March 2010. World Health Organization. https://iris.who.int/handle/10665/44412 ; Comité de Expertos de la OMS sobre el Control de las Leishmaniasis & Organización Mundial de la Salud. (2012). Control de las leishmaniasis: informe de una reunión del Comité de Expertos de la OMS sobre el Control de las Leishmaniasis, Ginebra, 22 a 26 de marzo de 2010. Organización Mundial de la Salud. https://iris.who.int/handle/10665/82766
Technical specifications
N/A
Related Medical Devices in MeDevIS
SAGE IVD recommended including the visceral leishmaniasis (VL) direct agglutination test (DAT) in the third EDL:
• as a disease-specific IVD for use in clinical laboratories (EDL 3, Section II.b, Neglected tropical diseases);
• in an agglutination assay format;
• to aid in the diagnosis of clinically suspected visceral leishmaniasis. The group noted the need to ensure that the entry for this test category in EDL 3 is clearly linked to WHO guidelines stating that the VL DAT must be used in combination with a clinical definition.
• as a disease-specific IVD for use in clinical laboratories (EDL 3, Section II.b, Neglected tropical diseases);
• in an agglutination assay format;
• to aid in the diagnosis of clinically suspected visceral leishmaniasis. The group noted the need to ensure that the entry for this test category in EDL 3 is clearly linked to WHO guidelines stating that the VL DAT must be used in combination with a clinical definition.
As well as being supported by WHO guidelines for the diagnosis of visceral leishmaniasis (VL), the direct agglutination test (DAT) is a non-invasive, cost-effective test compared with alternative tests based on microscopy of bone marrow or lymph node aspirates or spleen puncture. It has a higher diagnostic accuracy compared with rK39 RDT in eastern Africa; and a higher sensitivity, negative predictive value (NPV) and positive predictive value (PPV) compared with rK39 antigen test for screening and diagnosis among HIV-infected patients. Its higher NPV among HIV-infected patients could help avoid unnecessary treatment with toxic medications in non-infected people.
Importantly, the DAT can be used in test-and-treat strategies targeting VL in LMICs, where the disease is often endemic, because it is easy to perform and requires minimum laboratory skills; it can be done on dried blood spots (DBS) that are collected in primary care settings and sent to higher care levels.
There is evidence that the accuracy of the direct agglutination test (DAT) is comparable to the rK39 antigen test and suitable for use as a diagnostic test in endemic regions, as is recommended in WHO and many national guidelines. Estimates of accuracy are only available from reviews more than 10 years old that suggest sensitivity of 95% (CI: 93–96%) and specificity of 86% (CI: 72–93%).
World Health Organization. (2021). The selection and use of essential in vitro diagnostics: report of the third meeting of the WHO Strategic Advisory Group of Experts on In Vitro Diagnostics, 2020 (including the third WHO model list of essential in vitro diagnostics). World Health Organization. https://iris.who.int/handle/10665/339064