Evaluation of Antibody Detection Tests for Visceral Leishmaniasis Diagnosis in Eastern Africa

Evaluation of Antibody Detection Tests for Visceral Leishmaniasis Diagnosis in Eastern Africa

According to recent estimates by the World Health Organization (WHO) on eastern Africa, not all visceral leishmaniasis (VL) cases reported are confirmed by a laboratory test, probably due to limited access to accurate diagnostic tests and poor reporting. The main approach for VL diagnosis involves antibody detection using the rK39 rapid diagnostic test (RDT) and alternatively the direct agglutination test (DAT) to confirm clinically suspected cases. Suspected cases with negative rK39 RDT and/or DAT results are referred to facilities where examination of tissue aspirate (spleen, bone marrow, lymph node) by microscopy is available. Unfortunately, the diagnostic performance of rK39 in eastern Africa is suboptimal, particularly in settings with a high VL/HIV co-infection rate. A recently developed RDT, based on the recombinant antigen rK28, may overcome this problem, with studies reporting better performance than the rK39. However, data are not definitive, as studies comparing rK28 RDTs with rK39 RDT are limited. Another recently developed RDT detects immunoglobulin G1 (IgG1) specific to Leishmania and has shown promising results in the Indian subcontinent. This study aims to undertake a multi-country assessment of the performance of rK28 and IgG1 RDTs, as compared to the currently used rK39 RDT.

Primary objective and endpoint: To evaluate the performance of different diagnostic tests in detecting anti-Leishmania antibodies to improve early diagnosis of VL in eastern Africa, in particular Ethiopia, and Kenya. Evaluation of the diagnostic performance of the RDTs for primary VL diagnosis based on estimates of sensitivity, specificity, positive and negative predictive values, as well as the degree of agreement between tests.

Design: Prospective single arm diagnostic accuracy study. Multicountry. With participants being suspected cases of VL

Inclusion Criteria:

• Patient with clinical signs compatible with VL.
• Is a first VL episode suspected.
• Patient ≥ 5 years old (≥ 4 years old in Kenya).
• Patient from whom written informed consent can be obtained or signed by parent or legal guardian if patient is under 18 years of age. In the case of minors, assent from the children (12-17 years old in Ethiopia, Uganda and Sudan, and 13-17 years old in Kenya) will be obtained, as per country legal requirements.
• Clinical samples required VL diagnosis (peripheral blood, lymph node or bone marrow or spleen aspirate) can be obtained from the patient and patient shows willingness.

Exclusion Criteria:

• Patient already on treatment for VL.
• Patient is a suspected VL relapse case.
• Patient has had previous VL episodes.
• Patients < 5 years old (< 4 years old in Kenya).
• Pregnant woman.
• Patient has post/para-kala-azar dermal leishmaniasis (PKDL).