Reimagining leprosy elimination with AI analysis of a combination of skin lesion images with demographic and clinical data.

Background: Leprosy is an infectious disease that mostly affects underserved populations. Although it has been largely eliminated, still about 200'000 new patients are diagnosed annually. In the absence of a diagnostic test, clinical diagnosis is often delayed, potentially leading to irreversible neurological damage and its resulting stigma, as well as continued transmission. Accelerating diagnosis could significantly contribute to advancing global leprosy elimination. Digital and Artificial Intelligence (AI) driven technology has shown potential to augment health workers abilities in making faster and more accurate diagnosis, especially when using images such as in the fields of dermatology or ophthalmology. That made us start the quest for an AI-driven diagnosis assistant for leprosy, based on skin images. Methods: Here we describe the accuracy of an AI-enabled image-based diagnosis assistant for leprosy, called AI4Leprosy, based on a combination of skin images and clinical data, collected following a standardized process. In a Brazilian leprosy national referral center, 222 patients with leprosy or other dermatological conditions were included, and the 1229 collected skin images and 585 sets of metadata are stored in an open-source dataset for other researchers to exploit. Findings: We used this dataset to test whether a CNN-based AI algorithm could contribute to leprosy diagnosis and employed three AI models, testing images and metadata both independently and in combination. AI modeling indicated that the most important clinical signs are thermal sensitivity loss, nodules and papules, feet paresthesia, number of lesions and gender, but also scaling surface and pruritus that were negatively associated with leprosy. Using elastic-net logistic regression provided a high classification accuracy (90%) and an area under curve (AUC) of 96.46% for leprosy diagnosis. Interpretation: Future validation of these models is underway, gathering larger datasets from populations of different skin types and collecting images with smartphone cameras to mimic real world settings. We hope that the results of our research will lead to clinical solutions that help accelerate global leprosy elimination. Funding: This study was partially funded by Novartis Foundation and Microsoft (in-kind contribution).

Preventing leprosy with retrospective active case finding combined with single-dose rifampicin for contacts in a low endemic setting: results of the Leprosy Post-Exposure Prophylaxis program in Cambodia.

Post-exposure prophylaxis (PEP) with single-dose rifampicin (SDR) reduces the risk of developing leprosy among contacts of leprosy patients. Most evidence for the feasibility of the intervention is from highly endemic settings while low-endemic areas present unique challenges including reduced awareness of the disease among the population and in the health system, and the only sporadic occurrence of cases which together make defining any type of routine process challenging. We complemented the retrospective active case finding (RACF) approach with SDR administration to eligible contacts, and piloted the intervention across 31 operational districts in Cambodia. The aim was to demonstrate the feasibility of improving early case detection and administering SDR in a low endemic setting. The intervention focused on leprosy patients diagnosed since 2011 and was implemented between October 2016 - September 2019. The "drives" approach was employed to trace contacts: a trained team systematically contacted all eligible cases in a district, traced and screened contacts, and administered SDR. A total of 555 index patients were traced by the drive team, and 10,410 contacts in their household and 5 immediate neighbor houses listed. Among these contacts, 72.0% could be screened while most others were absent on the screening day. A total of 33 new leprosy cases were diagnosed and 6189 contacts received SDR (82.6% of the screened contacts). Sixty-one contacts refused SDR administration. We conclude that integrating PEP with SDR in RACF campaigns is feasible, and that this approach is appropriate in low resource and low endemic settings. Over time, evidence on whether or not the approach reduced leprosy transmission in Cambodia, may become clear.

The long-term impact of the Leprosy Post-Exposure Prophylaxis (LPEP) program on leprosy incidence: A modelling study.

BACKGROUND: The Leprosy Post-Exposure Prophylaxis (LPEP) program explored the feasibility and impact of contact tracing and the provision of single dose rifampicin (SDR) to eligible contacts of newly diagnosed leprosy patients in Brazil, India, Indonesia, Myanmar, Nepal, Sri Lanka and Tanzania. As the impact of the programme is difficult to establish in the short term, we apply mathematical modelling to predict its long-term impact on the leprosy incidence. METHODOLOGY: The individual-based model SIMCOLEP was calibrated and validated to the historic leprosy incidence data in the study areas. For each area, we assessed two scenarios: 1) continuation of existing routine activities as in 2014; and 2) routine activities combined with LPEP starting in 2015. The number of contacts per index patient screened varied from 1 to 36 between areas. Projections were made until 2040. PRINCIPAL FINDINGS: In all areas, the LPEP program increased the number of detected cases in the first year(s) of the programme as compared to the routine programme, followed by a faster reduction afterwards with increasing benefit over time. LPEP could accelerate the reduction of the leprosy incidence by up to six years as compared to the routine programme. The impact of LPEP varied by area due to differences in the number of contacts per index patient included and differences in leprosy epidemiology and routine control programme. CONCLUSIONS: The LPEP program contributes significantly to the reduction of the leprosy incidence and could potentially accelerate the interruption of transmission. It would be advisable to include contact tracing/screening and SDR in routine leprosy programmes.

Leprosy post-exposure prophylaxis with single-dose rifampicin (LPEP): an international feasibility programme.

BACKGROUND: Innovative approaches are required for leprosy control to reduce cases and curb transmission of Mycobacterium leprae. Early case detection, contact screening, and chemoprophylaxis are the most promising tools. We aimed to generate evidence on the feasibility of integrating contact tracing and administration of single-dose rifampicin (SDR) into routine leprosy control activities. METHODS: The leprosy post-exposure prophylaxis (LPEP) programme was an international, multicentre feasibility study implemented within the leprosy control programmes of Brazil, India, Indonesia, Myanmar, Nepal, Sri Lanka, and Tanzania. LPEP explored the feasibility of combining three key interventions: systematically tracing contacts of individuals newly diagnosed with leprosy; screening the traced contacts for leprosy; and administering SDR to eligible contacts. Outcomes were assessed in terms of number of contacts traced, screened, and SDR administration rates. FINDINGS: Between Jan 1, 2015, and Aug 1, 2019, LPEP enrolled 9170 index patients and listed 179 769 contacts, of whom 174 782 (97·2%) were successfully traced and screened. Of those screened, 22 854 (13·1%) were excluded from SDR mainly because of health reasons and age. Among those excluded, 810 were confirmed as new patients (46 per 10 000 contacts screened). Among the eligible screened contacts, 1182 (0·7%) refused prophylactic treatment with SDR. Overall, SDR was administered to 151 928 (86·9%) screened contacts. No serious adverse events were reported. INTERPRETATION: Post-exposure prophylaxis with SDR is safe; can be integrated into different leprosy control programmes with minimal additional efforts once contact tracing has been established; and is generally well accepted by index patients, their contacts, and health-care workers. The programme has also invigorated local leprosy control through the availability of a prophylactic intervention; therefore, we recommend rolling out SDR in all settings where contact tracing and screening have been established. FUNDING: Novartis Foundation.

Leprosy post-exposure prophylaxis with single-dose rifampicin (LPEP): an international feasibility programme

Background: Innovative approaches are required for leprosy control to reduce cases and curb transmission of Mycobacterium leprae. Early case detection, contact screening, and chemoprophylaxis are the most promising tools. We aimed to generate evidence on the feasibility of integrating contact tracing and administration of single-dose rifampicin (SDR) into routine leprosy control activities. Methods The leprosy post-exposure prophylaxis (LPEP) programme was an international, multicentre feasibility study implemented within the leprosy control programmes of Brazil, India, Indonesia, Myanmar, Nepal, Sri Lanka, and Tanzania. LPEP explored the feasibility of combining three key interventions: systematically tracing contacts of individuals newly diagnosed with leprosy; screening the traced contacts for leprosy; and administering SDR to eligible contacts. Outcomes were assessed in terms of number of contacts traced, screened, and SDR administration rates. Findings Between Jan 1, 2015, and Aug 1, 2019, LPEP enrolled 9170 index patients and listed 179 769 contacts, of whom 174782 (97·2%) were successfully traced and screened. Of those screened, 22 854 (13·1%) were excluded from SDR mainly because of health reasons and age. Among those excluded, 810 were confirmed as new patients (46 per 10 000 contacts screened). Among the eligible screened contacts, 1182 (0·7%) refused prophylactic treatment with SDR. Overall, SDR was administered to 151 928 (86·9%) screened contacts. No serious adverse events were reported. Interpretation Post-exposure prophylaxis with SDR is safe; can be integrated into different leprosy control programmes with minimal additional efforts once contact tracing has been established; and is generally well accepted by index patients, their contacts, and health-care workers. The programme has also invigorated local leprosy control through the availability of a prophylactic intervention; therefore, we recommend rolling out SDR in all settings where contact tracing and screening have been established(AU).

The long-term impact of the leprosy post-exposure prophylaxis (LPEP) program on leprosy incidence: a modelling study

The Leprosy Post-Exposure Prophylaxis (LPEP) program explored the feasibility and impact of contact tracing and the provision of SDR to eligible contacts of newly diagnosed leprosy patients in states or districts of Brazil, India, Indonesia, Myanmar, Nepal, Sri Lanka and Tanzania. This study investigated the long-term impact of the LPEP program on the leprosy new case detection rate (NCDR). Our results show that LPEP could reduce the NCDR beyond the impact of the routine leprosy control programme and that many new cases could be prevented. The benefit of LPEP increases gradually over time. LPEP could accelerate the time of reaching predicted NCDR levels of 2040 under routine program by up to six years. Furthermore, we highlighted how the impact varies between countries due to differences in the number of contacts per index patient screened and differences in leprosy epidemiology and national control programme. Generally, including both household contacts and neighbours (> 20 contacts per index patient) would yield the highest impact.

Prolaxis post-exposición para lepra con dosis única de rifampicina: manual para su implementación / Post-exposure prolaxis for leprosy with a single dose of rifampicin: a manual for its implementation

Objetivo: La profilaxis post-exposición de la lepra con dosis única de rifampicina (SDR-PEP) ha demostrado ser efectiva y aplicable y está recomendada por la OMS desde 2018. Esta caja de herramientas SDR-PEP se desarrolló a través de la experiencia de la profilaxis lepra post-eliminación (LPEP). Se ha diseñado para facilitar y estandarizar la implementación del seguimiento de contactos y la administración SDR-PEP en regiones y países que iniciaron la intervención. Resultados: Se desarrollaron cuatro instrumentos, incorporando la evidencia existente actual para SDR-PEP y los métodos y enseñanzas del proyecto LPEP en ocho países. (1) El conjunto de diapositivas Powerpoint política/apoyo que ayudarán a los programadores sobre la evidencia, practicabilidad y recursos necesarios para SDR-PEP, (2) La colección de diapositivas PowerPoint sobre formación e implementación en el campo para formar al personal implicado en el seguimiento de contactos y PEP con SDR, (3) manual genérico de campo SDR-PEP que puede ser usado para formar un protocolo específico de campo para el seguimiento de contactos y SDR-PEP como referencia para el personal directamente implicado. Finalmente, (4) el manual director SDR-PEP, que resume los distintos componentes de la caja de herramientas y contiene las instrucciones para su uso. Conclusión: En respuesta al interés manifestado por varios países de implementar el seguimiento de contactos de lepra con PEP con SDR, con las recomendaciones OMS sobre SDR-PEP, esta caja de herramientas basada en la evidencia concreta pero flexible, ha sido diseñada para servir a los directores de programas nacionales de lepra con un medio práctico para trasladar los planteamientos a la práctica. Está disponible gratuitamente en la página de Infolep y actualizada constantemente: https://www.leprosy-information.org/keytopic/leprosy-post-exposure-prophylaxis-lpep-programme(AU).

Objective: Leprosy post-exposure prophylaxis with single-dose rifampicin (SDRPEP) has proven effective and feasible, and is recommended by WHO since 2018. This SDR-PEP toolkit was developed through the experience of the leprosy post-exposure prophylaxis (LPEP) programme. It has been designed to facilitate and standardise the implementation of contact tracing and SDR-PEP administration in regions and countries that start the intervention. Results: Four tools were developed, incorporating the current evidence for SDRPEP and the methods and learnings from the LPEP project in eight countries. (1) the SDR-PEP policy/advocacy PowerPoint slide deck which will help to inform policy makers about the evidence, practicalities and resources needed for SDR-PEP, (2) the SDR-PEP field implementation training PowerPoint slide deck to be used to train front line staff to implement contact tracing and PEP with SDR, (3) the SDR-PEP generic field guide which can be used as a basis to create a location specific field protocol for contact tracing and SDR-PEP serving as a reference for frontline field staff. Finally, (4) the SDR-PEP toolkit guide, summarising the different components of the toolkit and providing instructions on its optimal use. Conclusion: In response to interest expressed by countries to implement contact tracing and leprosy PEP with SDR in the light of the WHO recommendation of SDRPEP, this evidence-based, concrete yet flexible toolkit has been designed to serve national leprosy programme managers and support them with the practical means to translate policy into practice. The toolkit is freely accessible on the Infolep homepages and updated as required: https://www.leprosy-information.org/keytopic/leprosy-postexposure-prophylaxis-lpep-programme(AU).

Programa post-exposición a la profilaxis de la Lepra (LPEP): Actualización y análisis interno / No disponible

Se requieren nuevos planteamientos para incrementar el control de la lepra, disminuir el número de personas afectadas y cortar la transmisión. Para conseguir este objetivo las mejores soluciones son la detección precoz. El cribaje de contactos y la quimioprofilaxis. El Programa Profilaxis Post-exposición a la Lepra (LPEP) ayuda a demostrar la viabilidad de integrar el rastreo de contactos y dosis única de rifampicina (SDR) en las actividades rutinarias de control de la enfermedad. El programa LPEP está implementado entre los programas de control de la lepra de Brasil, Camboya, India, Indonesia, Myanmar, Nepal, Sri Lanka y Tanzania. Se centra en tres objetivos: rastro de contactos de nuevos pacientes diagnosticados de lepra, cribaje de contactos y administración de SDR a los contactos seleccionados. Las adaptaciones de protocolos países-específicos se refieren a la definición de contacto, edad mínima para SDR y personal implicado. La calidad de la evidencia se mantiene mediante coordinación central, documentación detallada y supervisión. Ya se han completado alrededor de 2 años de trabajo de campo en siete países en julio de 2017. Los 5,941 pacientes índice registrados (89·4% de los registrados) han identificado un total de 123,311 contactos, de los cuales el 99·1% ha sido rastreado y cribado. De entre ellos, se identificaron 406 nuevos pacientes de lepra (329/100,000) y a 10,883 (8·9%) no se les administró SDR por diversos motivos. También 785 contactos (6·7%) rehusó tomar la profilaxis con SDR. En total, se administró SDR al 89·0% de los contactos registrados. La profilaxis post-exposición con SDR es segura; se puede integrar en los programas rutinarios de control de la lepra y es generalmente bien aceptada por el paciente índice, sus contactos y el personal sanitario. El programa también consigue estimular los programas locales de control de la lepra

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

The Leprosy Post-Exposure Prophylaxis (LPEP) programme: update and interim analysis.

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.

Multidrug therapy for leprosy: a game changer on the path to elimination.

Leprosy is present in more than 100 countries, where it remains a major cause of peripheral neuropathy and disability. Attempts to eliminate the disease have faced various obstacles, including characteristics of the causative bacillus Mycobacterium leprae: the long incubation period, limited knowledge about its mode of transmission, and its poor growth on culture media. Fortunately, the leprosy bacillus is sensitive to several antibiotics. The first antibiotic to be widely used for leprosy treatment was dapsone in the 1950s, which had to be taken over several years and was associated with increasing bacterial resistance. Therefore, in 1981, WHO recommended that all registered patients with leprosy should receive combination therapy with three antibiotics: rifampicin, clofazimine, and dapsone. Global implementation of this highly effective multidrug therapy took about 15 years. In 1985, 5·3 million patients were receiving multidrug therapy; by 1991, this figure had decreased to 3·1 million (a decrease of 42%) and, by 2000, to 597 232 (a decrease of almost 90%). This reduction in the number of patients registered for treatment was due to shortening of the treatment regimen and achievement of 100% coverage with multidrug therapy. This achievement, which owed much to WHO and the donors of the multidrug therapy components, prompted WHO in 1991 to set a global target of less than one case per 10 000 population by 2000 to eliminate the disease as a public health problem. All but 15 countries achieved this target. Since 2000, about 250 000 new cases of leprosy have been detected every year. We believe an all-out campaign by a global leprosy coalition is needed to bring that figure down to zero.

Multidrug therapy for leprosy: a game changer on the path to elimination

Leprosy is present in more than 100 countries, where it remains a major cause of peripheral neuropathy and disability. Attempts to eliminate the disease have faced various obstacles, including characteristics of the causative bacillus Mycobacterium leprae: the long incubation period, limited knowledge about its mode of transmission, and its poor growth on culture media. Fortunately, the leprosy bacillus is sensitive to several antibiotics. The first antibiotic to be widely used for leprosy treatment was dapsone in the 1950s, which had to be taken over several years and was associated with increasing bacterial resistance. Therefore, in 1981, WHO recommended that all registered patients with leprosy should receive combination therapy with three antibiotics: rifampicin, clofazimine, and dapsone. Global implementation of this highly effective multidrug therapy took about 15 years. In 1985, 5·3 million patients were receiving multidrug therapy; by 1991, this figure had decreased to 3·1 million (a decrease of 42%) and, by 2000, to 597 232 (a decrease of almost 90%). This reduction in the number of patients registered for treatment was due to shortening of the treatment regimen and achievement of 100% coverage with multidrug therapy. This achievement, which owed much to WHO and the donors of the multidrug therapy components, prompted WHO in 1991 to set a global target of less than one case per 10 000 population by 2000 to eliminate the disease as a public health problem. All but 15 countries achieved this target. Since 2000, about 250 000 new cases of leprosy have been detected every year. We believe an all-out campaign by a global leprosy coalition is needed to bring that figure down to zero.

Leprosy Post-Exposure Prophylaxis (LPEP) programme: study protocol for evaluating the feasibility and impact on case detection rates of contact tracing and single dose rifampicin.

INTRODUCTION: The reported number of new leprosy patients has barely changed in recent years. Thus, additional approaches or modifications to the current standard of passive case detection are needed to interrupt leprosy transmission. Large-scale clinical trials with single dose rifampicin (SDR) given as post-exposure prophylaxis (PEP) to contacts of newly diagnosed patients with leprosy have shown a 50-60% reduction of the risk of developing leprosy over the following 2 years. To accelerate the uptake of this evidence and introduction of PEP into national leprosy programmes, data on the effectiveness, impact and feasibility of contact tracing and PEP for leprosy are required. The leprosy post-exposure prophylaxis (LPEP) programme was designed to obtain those data. METHODS AND ANALYSIS: The LPEP programme evaluates feasibility, effectiveness and impact of PEP with SDR in pilot areas situated in several leprosy endemic countries: India, Indonesia, Myanmar, Nepal, Sri Lanka and Tanzania. Complementary sites are located in Brazil and Cambodia. From 2015 to 2018, contact persons of patients with leprosy are traced, screened for symptoms and assessed for eligibility to receive SDR. The intervention is implemented by the national leprosy programmes, tailored to local conditions and capacities, and relying on available human and material resources. It is coordinated on the ground with the help of the in-country partners of the International Federation of Anti-Leprosy Associations (ILEP). A robust data collection and reporting system is established in the pilot areas with regular monitoring and quality control, contributing to the strengthening of the national surveillance systems to become more action-oriented. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the relevant ethics committees in the countries. Results and lessons learnt from the LPEP programme will be published in peer-reviewed journals and should provide important evidence and guidance for national and global policymakers to strengthen current leprosy elimination strategies.

Role of contact tracing and prevention strategies in the interruption of leprosy transmission.

The global prevalence of leprosy has declined from 5.2 million in the 1980 s to 200,000 today. However, the new case detection rate remains high: over the last 8 years, around 220,000-250,000 people have been diagnosed with leprosy each year. In June 2013, an international meeting was organised by the Novartis Foundation for Sustainable Development in Geneva, Switzerland,2 with the objective of discussing the feasibility of interrupting the transmission of leprosy. The group of physicians, epidemiologists and public health professionals concluded that a successful programme would require early diagnosis and prompt multidrug therapy (MDT) for all patients, tracing and post-exposure prophylaxis (PEP) for contacts of patients newly diagnosed with leprosy, improvements in diagnostic tools, as well as strict epidemiological surveillance and response systems to monitor progress. As a follow-up, a second expert group meeting was convened by the Novartis Foundation in January 2014 in Zurich, Switzerland, with the objective of reviewing the evidence for chemoprophylaxis in contacts and high-risk communities. The meeting also considered the definitions of 'contacts' and 'contact tracing', discussed alternative prophylaxis regimens, preliminary findings of operational pilot projects on PEP in Indonesia, as well as the development of diagnostic tools, and identified the priority questions for operational research in leprosy transmission. The meeting outlined how contact tracing and chemoprophylaxis programmes can be implemented to interrupt leprosy transmission. The expert panel reached the following conclusions: Chemoprophylaxis with single-dose rifampicin (SDR) is efficacious in reducing the risk of developing leprosy, although the protective effect appears to be smaller in contacts closer to the index patient than in more distant contacts.3 SDR can be targeted to contacts or implemented as community mass prophylaxis in certain circumstances; the preferred approach depends on local factors, such as the case detection rate, the level of community stigma against leprosy, and the degree of access to healthcare for patients and contacts. Alternative prophylaxis regimens and the role of post-exposure immunoprophylaxis need to be further investigated. Contact tracing combined with PEP across very diverse settings offers protection rates similar to those reported in controlled trials. For high-incidence pockets ('hotspots') or remote or confined high-incidence populations ('hotpops'), blanket administration of PEP may be a better option. Implementation of contact-tracing programmes is feasible and cost-effective, particularly in high-risk groups, but it should be integrated into local healthcare services to ensure their long-term sustainability. Funding and support must be maintained after an initial pilot has finished. New programmes for contact tracing need effective surveillance systems to enable appropriate follow-up and outcome evaluation. The Novartis Foundation and Netherlands Leprosy Relief (NLR) are currently developing and implementing a large international programme to demonstrate the feasibility, acceptability, cost-effectiveness and real-world efficacy of PEP as a strategy to interrupt leprosy transmission, in six pilot projects in Asia, Africa and South America. These new pilot projects will be developed together with the local health authorities, healthcare workers, communities and patients, in order to create local ownership from the outset. The pilots should aim to be scalable and sustainable, and should therefore include an objective outcome assessment. Local ownership ensures that locally appropriate language and definitions of contacts are used in each of the pilots. A test to identify subclinical disease and distinguish M. leprae exposure from infection would facilitate early and appropriate therapy (with PEP or MDT). The identification and validation of new, sensitive biomarkers for M. leprae infection and exposure may allow better targeting of PEP to those contacts at highest risk of developing leprosy.