Global landscape of molecular and immunological diagnostic tests for human leishmaniasis: a systematic review and meta-analysis

BackgroundLeishmaniasis constitutes a serious global public health concern. It is a complex parasitic disease characterized by a spectrum of clinical forms with varying severity, driven by host immune responses and immunopathology. Its accurate diagnosis is essential for guiding timely treatment. Yet, diagnosing leishmaniasis is challenging and requires a combination of tests. Methodology/Principal findingsWe conducted a systematic review and meta-analysis to evaluate the applicability and diagnostic accuracy of molecular and immunological tests for the laboratory diagnosis of human tegumentary leishmaniasis (TL) and visceral leishmaniasis (VL). We searched the PubMed database for studies published between 1990 and 2021 on leishmaniasis diagnosis. Following PRISMA statement recommendations, we included 165 publications that met the selection criteria. Among the evaluated tests, polymerase chain reaction (PCR)-based tests showed good diagnostic performance, with area under the curve values (restricted to observed FPRs, AUCFPR) of 0.919 and 0.965 for the diagnosis of TL and VL, respectively. For TL, serological tests showed median sensitivities ranging from 83.3% to 88.1% and median specificities ranging from 82.0% to 92.4%, whereas the leishmanin (Montenegro) skin test had a median sensitivity of 91.7% and a median specificity of 83.4%. For VL, the direct agglutination test (DAT) and enzyme-linked immunosorbent assay (ELISA) exhibited higher sensitivity (median 93.0-93.8%) than rapid diagnostic tests (RDT, 89.1%) and the immunofluorescence antibody test (IFAT, 82.0%). These four tests displayed high specificity (median 95.5-96.9%). DAT showed comparable performance to molecular tests, with an AUCFPR of 0.966. Conclusions/SignificanceMolecular tests exhibited high accuracy in diagnosing tegumentary and visceral leishmaniasis. Nevertheless, these tests have yet to be incorporated into routine clinical practice in endemic regions, as they still require specialized technical expertise and robust laboratory infrastructure. We advocate for the development and implementation of diagnostic procedures tailored to the needs of each endemic setting, considering local contexts and available resources, wherein molecular tests could facilitate early, accurate diagnosis of leishmaniasis. Author SummaryLeishmaniasis remains a significant global public health challenge, with millions of people at risk of infection, particularly in rural areas of tropical and subtropical regions. This parasitic disease presents with diverse clinical forms, ranging from skin ulcers to life-threatening mucosal or visceral organ damage. Early and accurate diagnosis of leishmaniasis is critical for timely treatment, in turn impacting disease control. Diagnosing leishmaniasis requires reliable laboratory tests. This work is a comprehensive systematic review and meta-analysis to evaluate the diagnostic accuracy of widely used molecular and immunological tests for human leishmaniasis, focusing on both tegumentary and visceral forms. Our findings reveal that PCR-based molecular tests enable highly accurate diagnosis of all forms of leishmaniasis, outperforming serological tests in many instances. Despite this, their use in endemic regions remains limited due to the need for specialized equipment and trained personnel. We emphasize the performance of immunological tests, such as DAT, LST, and ELISA, which are used in clinical and research settings and can serve as a diagnostic complement in resource-limited settings. Ultimately, this work underscores the importance of developing tailored diagnostic algorithms that incorporate molecular tests alongside simpler, field-friendly diagnostic tools to improve early diagnosis of leishmaniasis and patient outcomes in diverse epidemiological contexts.