Leprosy Diagnostic Test Development As a Prerequisite Towards Elimination: Requirements from the User’s Perspective

Leprosy is the complex disease manifestation of Mycobacterium leprae infection. Although prevalence has declined from 5.2 million globally in the 1980s, new annual case detection rates (CDRs) remain high, at more than 200,000 new cases per year [1], indicating that additional leprosy control strategies are required to halt transmission. An Expert Meeting held in June 2013 in Geneva discussed strategies to transition from control to elimination and concluded that any viable programme would need to include: (i) early diagnosis and prompt multidrug therapy (MDT) for all patients, (ii) tracing and postexposure prophylaxis (PEP) for contacts of newly diagnosed patients, and (iii) strict epidemiological surveillance and systems to monitor progress [2]. Improved diagnostic tools would be of great value to achieve these goals. A subsequent international Expert Panel met, with the goal to define the required attributes of a diagnostic test for leprosy that would support and facilitate leprosy elimination efforts in terms of complete interruption of transmission of M. leprae. A tool for identifying leprosy cases (asymptomatic and any symptomatic form of leprosy) was identified as a prerequisite to elimination, thereby addressing the goals of the 2020 London Declaration on Neglected Tropical Diseases [3,4]. However, given the challenges of developing such a diagnostic test, a two-step strategy, starting with a confirmatory test for clinical diagnosis among symptomatic patients, was considered as a pragmatic approach. This article presents the considerations, target population, target profile, and current research activities for leprosy diagnostic tools from a user’s perspective.