Paul Saunderson

(1) Background: The global burden of leprosy is not shared equally; with the majority of cases being diagnosed in Brazil, India, and Indonesia. Understanding the methods of active case detection (ACD) used in high and low endemic regions is vital for the development of future screening programs. (2) Methods: A systematic search of three databases, PubMed, Embase and Web of Science, was conducted for English language papers, published since the year 2000, which discussed the use of active case detection methods for leprosy screening. The paper utilised the Integrated Screening Action Model (I-SAM) as a tool for the analysis of these methods. (3) Results: 23 papers were identified from 11 different countries. The papers identified 6 different methods of active case detection: Household contact/social contact identification; door-to-door case detection; screening questionnaire distribution; rapid village surveys; school-based screening; and prison-based screening. 15 were located in high endemic regions and 8 of these were located in low endemic regions. (4) Conclusions: For selecting the appropriate methods of active case finding, the leprosy endemicity must be taken into consideration. The findings contribute to policy decision making allowing for more successful future leprosy case detection programs to be designed, ultimately reducing the global burden of the disease, and achieving the WHO’s aim of zero leprosy.

The World Health Organization (WHO) publishes leprosy statistics each year. In 2022, the number of new cases increased compared with the previous two years, which were artificially low because of the COVID-19 pandemic. Reporting by countries continues to improve, as data systems and data quality become more standarized. The number of indicators being reported is increasing, but there is a limit to the amount of information that can be publshed in the Weekly Epidemiological Record. Methods to disseminate further detailed statistics need to be found, as they can be an important stimulus to improving services.

Early case detection is now seen as one of the most important tasks for leprosy programs. It can improve the experience of people who develop the disease, as early treatment prevents many of the complications that frequently occur in people whose diagnosis is delayed. It is also an important factor in efforts to prevent ongoing transmission, as early treatment reduces the spread to close contacts. Perhaps more importantly, it provides a platform for appropriate management of those contacts, in whom clinical disease can be prevented in a significant proportion by post-exposure prophylaxis. This Editorial reflects on two recent conferences, one organized by the Global Partnership for Zero Leprosy (GPZL) on the research needs related to early case detection, and the second run by ILEP on the practical aspects of promoting early case detection in the field. With recent developments in mapping and in post-exposure prophylaxis (PEP), we have the tools to greatly improve case-finding and work towards zero leprosy.

Although leprosy was widespread in Europe in the Middle Ages, the whole continent is now on the brink of declaring an end to local transmission of the disease. With the high level of international travel, leprosy is still diagnosed in many European countries, but rarely in people who have never traveled to or lived in a more endemic area of the world. The occurrence of leprosy in local children is an indication of recent transmission and this seems to have stopped throughout Europe, although confirming this with reliable data is a major challenge. Sporadic cases (occasional new cases occurring in a given area that are unrelated to other known cases) and autochthonous (locally acquired) cases in older adults point to some transmission in previous decades. In countries where local transmission has stopped, there is no evidence of any spread of leprosy from international travelers or migrants to the local population. Verification by WHO of the end of transmission of leprosy is beginning to occur in some countries, but crucially depends on good data concerning new cases diagnosed over previous years. Policies for the future should include: (a) sustainable provision within national health services for the diagnosis and treatment of leprosy in the few cases that do occur, usually in the migrant population, with meticulous recording and reporting of case data; (b) sustainable services for the care of people with leprosy-related disability, and the continued fight against stigma and discrimination towards those affected.

Background: Leprosy is an infectious disease caused byMycobacterium leprae. As incidence begins to decline, the characteristics of new cases shifts away from those observed in highly endemic areas, revealing potentially important insights into possible ongoing sources of transmission. We aimed to investigate whether transmission is driven mainly by undiagnosed and untreated new leprosy cases in the community, or by incompletely treated or relapsing cases.Methodology/Principal findings: A literature search of major electronic databases was conducted in January, 2020 with 134 articles retained out of a total 4318 records identified (PROSPERO ID: CRD42020178923). We presented quantitative data from leprosy case records with supporting evidence describing the decline in incidence across several contexts. BCG vaccination, active case finding, adherence to multidrug therapy and continued surveillance following treatment were the main strategies shared by countries who achieved a substantial reduction in incidence. From 3950 leprosy case records collected across 22 low endemic countries, 48.3% were suspected to be imported, originating from transmission outside of the country. Most cases were multibacillary (64.4%) and regularly confirmed through skin biopsy, with 122 cases of suspected relapse from previous leprosy treatment. Family history was reported in 18.7% of cases, while other suspected sources included travel to high endemic areas and direct contact with armadillos. None of the countries included in the analysis reported a distinct increase in leprosy incidence in recent years.Conclusions/Significance: Together with socioeconomic improvement over time, several successful leprosy control programmes have been implemented in recent decades that led to a substantial decline in incidence. Most cases described in these contexts were multibacillary and numerous cases of suspected relapse were reported. Despite these observations, there was no indication that these cases led to a rise in new secondary cases, suggesting that they do not represent a large ongoing source of human-to-human transmission.

The ongoing transmission of Mycobacterium (M.) leprae reflected in a very slow decline in leprosy incidence, forces us to be innovative and conduct cutting-edge research. Single dose rifampicin (SDR) as post-exposure prophylaxis (PEP) for contacts of leprosy patients, reduces their risk to develop leprosy by 60%. This is a promising new preventive measure that can be integrated into routine leprosy control programmes, as is being demonstrated in the Leprosy Post-Exposure Programme that is currently ongoing in eight countries. The limited (60%) effectiveness of SDR is likely due to the fact that some contacts have a preclinical infection beyond the early stages for which SDR is not sufficient to prevent the development of clinical signs and symptoms of leprosy. An enhanced regimen, more potent against a higher load of leprosy bacteria, would increase the effectiveness of this preventive measure significantly. The Netherlands Leprosy Relief (NLR) is developing a multi-country study aiming to show that breaking the chain of transmission of M. leprae is possible, evidenced by a dramatic reduction in incidence. In this study the assessment of the effectiveness of an enhanced prophylactic regimen for leprosy is an important component. To define the so called PEP++ regimen for this intervention study, NLR convened an Expert Meeting that was attended by clinical leprologists, public health experts, pharmacologists, dermatologists and microbiologists. The Expert Meeting advised on combinations of available drugs, with known efficacy against leprosy, as well as on the duration of the intake, aiming at a risk reduction of 80–90%. To come to a conclusion the Expert Meeting considered the bactericidal, sterilising and bacteriostatic activity of the potential drugs. The criteria used to determine an optimal enhanced regimen were: effectiveness, safety, acceptability, availability, affordability, feasibility and not inducing drug resistance. The Expert Meeting concluded that the enhanced regimen for the PEP++ study should comprise three standard doses of rifampicin 600 mg (weight adjusted when given to children) plus moxifloxacin 400 mg given at four-weekly intervals. For children and for adults with contraindications for moxifloxacin, moxifloxacin should be replaced by clarithromycin 300 mg (weight adjusted).

Innovative approaches are required to further enhance leprosy control, reduce the number of people developing leprosy, and curb transmission. Early case detection, contact screening, and chemoprophylaxis currently is the most promising approach to achieve this goal. The Leprosy Post-Exposure Prophylaxis (LPEP) programme generates evidence on the feasibility of integrating contact tracing and single-dose rifampicin (SDR) administration into routine leprosy control activities in different settings. The LPEP programme is implemented within the leprosy control programmes of Brazil, Cambodia, India, Indonesia, Myanmar, Nepal, Sri Lanka and Tanzania. Focus is on three key interventions: tracing the contacts of newly diagnosed leprosy patients; screening the contacts for leprosy; and administering SDR to eligible contacts. Country-specific protocol adaptations refer to contact definition, minimal age for SDR, and staff involved. Central coordination, detailed documentation and rigorous supervision ensure quality evidence. Around 2 years of field work had been completed in seven countries by July 2017. The 5,941 enrolled index patients (89.4% of the registered) identified a total of 123,311 contacts, of which 99.1% were traced and screened. Among them, 406 new leprosy patients were identified (329/100,000), and 10,883 (8.9%) were excluded from SDR for various reasons. Also, 785 contacts (0.7%) refused the prophylactic treatment with SDR. Overall, SDR was administered to 89.0% of the listed contacts. Post-exposure prophylaxis with SDR is safe; can be integrated into the routines of different leprosy control programmes; and is generally well accepted by index patients, their contacts and the health workforce. The programme has also invigorated local leprosy control.