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) continua-tion 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 after-wards 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.</p

Leprosy epidemiological trends and diagnosis delay in three districts of Tanzania: A baseline study

Objectives Leprosy, also known as Hansen’s disease, is a slowly progressive and chronic infectious neglected tropical disease (NTD) caused by Mycobacterium leprae. This study was performed to assess the epidemiological trend of leprosy in the past five years in the three study districts in Tanzania in which a leprosy prevention intervention study (PEP4LEP) is implemented, and to determine the case detection delay at baseline. Methods Secondary data from the leprosy registry of the National Tuberculosis and Leprosy Program of Tanzania from 2015 to 2019 were used to describe the epidemiological trends of leprosy for the three study districts: Morogoro, Mvomero, and Lindi district council. A cross-sectional study was also conducted to assess the delay in leprosy diagnosis at baseline. The chi-square test was used to calculate statistical significance. Results Between 2015 and 2019, 657 new leprosy cases were detected in three districts. Of those cases, 247 (37.6%) were female patients, 5 (0.8%) had a grade 2 disability (G2D) and 516 (78.5%) had multibacillary (MB) leprosy. From the 50 adult leprosy patients interviewed for detection delay, 16 (32.0%) were females and 38 (76.0%) had MB leprosy. Overall, a mean case detection of 28.1 months (95% CI 21.5–34.7) and a median of 21.5 months were observed. Conclusion The three PEP4LEP study districts remain highly endemic, with long case detection delays observed that increase the risk of disabilities and contribute to ongoing leprosy transmission. Integrating activities such as contact screening and provision of post-exposure prophylaxis are therefore a necessary strategy in these endemic areas

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

BackgroundThe 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.MethodologyThe 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 findingsIn 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.ConclusionsThe 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