Visceral leishmaniasis (VL) is a deadly disease caused by infection with the Leishmania parasite. The majority of cases are found in South Asia, east Africa, and Brazil. As many as 310 million people are at risk of infection, and it is estimated that between 20,000 and 50,000 deaths result from VL annually. VL is spread through the bite of the sandfly vector, and it can be harbored by human and canine reservoirs. The parasite causes nonspecific symptoms such as fever and splenomegaly; if left untreated, VL typically

leads to death.

The World Health Organization (WHO) 2020 goal is to eliminate VL from the Indian subcontinent (i.e., achieve prevalence of less than 1 case per 100,000). The WHO set a number of goals for the Neglected Tropical Diseases (NTD) to be achieved by 2020, and the London Declaration on NTDs backed these goals with commitments from public and private institutions. The 3rd progress report of the London Declaration indicated that “priorities for progress” towards reaching VL goals include early detection of cases, improved access to diagnosis, and scale-up of diagnostic services.

In support of the London Declaration goals, PATH aims to catalyze engagement of the diagnostics industry and product development efforts. As part of this work, PATH assessed needs and landscaped potential solutions to improve diagnostic tools used to support VL elimination efforts. We conducted literature reviews, a product development landscape, and interviews with key stakeholders to identify gaps in current human VL diagnostics as well as emerging solutions. These findings were used to identify use cases for VL diagnostics, determine which tools address specific use cases, analyze progress toward robust diagnostics in the development pipeline, and ultimately to propose recommendations on how to improve availability, access, and adoption of VL diagnostics.

PATH identified four use cases for human VL diagnostics: diagnosing acute infection, diagnosing VLHIV coinfection, diagnosing post-kala-azar dermal leishmaniasis (PKDL), and treatment monitoring. We found that current tools and methods are likely sufficient for the early case detection needed to support elimination goals. However, current rapid diagnostic tests (RDTs) have limitations and new tools would benefit patients with HIV coinfection and PKDL, as well as improve treatment monitoring. We have developed the following recommendations:

1. Support ongoing efforts to ensure full access to, and adoption of, current antibody detection RDTs. Health systems and market research may be needed to support optimal uptake of currently available antibody tests.
2. Develop an antigen detection test to better diagnose VL-HIV coinfection and monitor treatment. There is a need for a noninvasive, field-friendly test that can identify active VL infections among HIV coinfected patients, as well as monitor for treatment failure and relapse.
3. Support research and development needed for next generation antibody detection RDTs. A noninvasive, sensitive rapid test is needed to enable treatment monitoring and detection of PKDL.