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. 2021 Feb 25;15(2):e0009146.
doi: 10.1371/journal.pntd.0009146. eCollection 2021 Feb.

Number of people requiring post-exposure prophylaxis to end leprosy: A modeling study

Anneke T Taal  1   2 , David J Blok  2 , Wim H van Brakel  1 , Sake J de Vlas  2 , Jan Hendrik Richardus  2
Affiliations

Number of people requiring post-exposure prophylaxis to end leprosy: A modeling study

Anneke T Taal et al. PLoS Negl Trop Dis. .

Abstract

Background: Worldwide, around 210,000 new cases of leprosy are detected annually. To end leprosy, i.e. zero new leprosy cases, preventive interventions such as contact tracing and post-exposure prophylaxis (PEP) are required. This study aims to estimate the number of people requiring PEP to reduce leprosy new case detection (NCD) at national and global level by 50% and 90%.

Methodology/principal findings: The individual-based model SIMCOLEP was fitted to seven leprosy settings defined by NCD and MB proportion. Using data of all 110 countries with known leprosy patients in 2016, we assigned each country to one of these settings. We predicted the impact of administering PEP to about 25 contacts of leprosy patients on the annual NCD for 25 years and estimated the number of contacts requiring PEP per country for each year. The NCD trends show an increase in NCD in the first year (i.e. backlog cases) followed by a significant decrease thereafter. A reduction of 50% and 90% of new cases would be achieved in most countries in 5 and 22 years if 20.6 and 40.2 million people are treated with PEP over that period, respectively. For India, Brazil, and Indonesia together, a total of 32.9 million people requiring PEP to achieve a 90% reduction in 22 years.

Conclusion/significance: The leprosy problem is far greater than the 210,000 new cases reported annually. Our model estimates of the number of people requiring PEP to achieve significant reduction of new leprosy cases can be used by policymakers and program managers to develop long-term strategies to end leprosy.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. The global change in new case detection and cumulative number of people requiring post-exposure prophylaxis (PEP) over a period of 25 years.
The orange line represents the change in the new case detection (NCD) and its 95% confidence interval. The blue line is the cumulative number of people requiring post-exposure prophylaxis and its 95% confidence interval. The dotted and dashed vertical line represents the time of 50% and 90% reduction in NCD, respectively.
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