Current knowledge on Mycobacterium leprae transmission: a systematic literature review

Bratschi, Martin W.; Steinmann, Peter; Wickenden, Anna; Gillis, Thomas P.

doi:10.47276/lr.86.2.142

Cited by 107 publications

(52 citation statements)

References 15 publications

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“…There are strong parallels here with Mycobacterium leprae , the agent of leprosy. Like BU, the mode of transmission of the leprosy bacillus is unclear, but the infective dose is known to be very low (10 bacteria) and epidemiological evidence suggests multiple transmission pathways, including entry of the bacteria after skin trauma [ 57 , 58 ]. Our infective dose estimate for M .…”

Section: Discussionmentioning

confidence: 99%

Mycobacterium ulcerans low infectious dose and mechanical transmission support insect bites and puncturing injuries in the spread of Buruli ulcer

et al. 2017

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Addressing the transmission enigma of the neglected disease Buruli ulcer (BU) is a World Health Organization priority. In Australia, we have observed an association between mosquitoes harboring the causative agent, Mycobacterium ulcerans, and BU. Here we tested a contaminated skin model of BU transmission by dipping the tails from healthy mice in cultures of the causative agent, Mycobacterium ulcerans. Tails were exposed to mosquito (Aedes notoscriptus and Aedes aegypti) blood feeding or punctured with sterile needles. Two of 12 of mice with M. ulcerans contaminated tails exposed to feeding A. notoscriptus mosquitoes developed BU. There were no mice exposed to A. aegypti that developed BU. Eighty-eight percent of mice (21/24) subjected to contaminated tail needle puncture developed BU. Mouse tails coated only in bacteria did not develop disease. A median incubation time of 12 weeks, consistent with data from human infections, was noted. We then specifically tested the M. ulcerans infectious dose-50 (ID50) in this contaminated skin surface infection model with needle puncture and observed an ID50 of 2.6 colony-forming units. We have uncovered a biologically plausible mechanical transmission mode of BU via natural or anthropogenic skin punctures.

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Section: Discussionmentioning

confidence: 99%

Mycobacterium ulcerans low infectious dose and mechanical transmission support insect bites and puncturing injuries in the spread of Buruli ulcer

et al. 2017

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“…As density-dependent transmission was assumed, but is known to be a simplification of true human contact rates [ 32 ], the above process was repeated for a frequency-dependent transmission model. In this model, the force of infection λ f becomes where and are adjusted from the density-dependent model to account for population size.…”

Section: Methodsmentioning

confidence: 99%

Proposing a Compartmental Model for Leprosy and Parameterizing Using Regional Incidence in Brazil

Smith

2016

PLoS Negl Trop Dis

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Hansen’s disease (HD), or leprosy, is still considered a public health risk in much of Brazil. Understanding the dynamics of the infection at a regional level can aid in identification of targets to improve control. A compartmental continuous-time model for leprosy dynamics was designed based on understanding of the biology of the infection. The transmission coefficients for the model and the rate of detection were fit for each region using Approximate Bayesian Computation applied to paucibacillary and multibacillary incidence data over the period of 2000 to 2010, and model fit was validated on incidence data from 2011 to 2012. Regional variation was noted in detection rate, with cases in the Midwest estimated to be infectious for 10 years prior to detection compared to 5 years for most other regions. Posterior predictions for the model estimated that elimination of leprosy as a public health risk would require, on average, 44–45 years in the three regions with the highest prevalence. The model is easily adaptable to other settings, and can be studied to determine the efficacy of improved case finding on leprosy control.

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“…Transmission of Mycobacterium leprae , the causative agent of leprosy, is mainly human-to-human via the respiratory route. Once infected, it can take two to twelve years before the first signs and symptoms appear, although only a small proportion will develop the disease [ 2 ]. Worldwide, 208,619 new cases of leprosy were detected and reported in 2018, of which 80% in India, Brazil, and Indonesia [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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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Current knowledge on Mycobacterium leprae transmission: a systematic literature review

Cited by 107 publications

References 15 publications

Mycobacterium ulcerans low infectious dose and mechanical transmission support insect bites and puncturing injuries in the spread of Buruli ulcer

Mycobacterium ulcerans low infectious dose and mechanical transmission support insect bites and puncturing injuries in the spread of Buruli ulcer

Proposing a Compartmental Model for Leprosy and Parameterizing Using Regional Incidence in Brazil

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

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