Leprosy Transmission in Amazonian Countries: Current Status and Future Trends

Abstract

Purpose of Review Leprosy is one of the first pathologies described in the history of mankind. However, the ecology, transmission, and pathogenicity of the incriminated bacilli remain poorly understood. Despite effective treatment freely distributed worldwide since 1995, around 200,000 new cases continue to be detected yearly, mostly in the tropics. This review aims to discuss the unique characteristics of leprosy in Amazonian countries, which exhibit a very heterogeneous prevalence among human and animal reservoirs. Recent Findings Groundbreaking discoveries made in the last 15 years have challenged the dogmas about leprosy reservoirs, transmission, and treatment. The discovery of a new leprosy causative agent in 2008 and the scientific proof of zoonosis transmission of leprosy by nine-banded armadillos in the southern USA in 2011 challenged the prospects of leprosy eradication. In the Amazonian biome, nine-banded and other armadillo species are present but the lack of large-scale studies does not yet allow accurate assessment of the zoonotic risk. Brazil is the second country in the world reporting the highest number of new leprosy cases annually. The disease is also present, albeit with different rates, in all neighboring countries. Throughout the Amazonian biome, leprosy is mainly found in hyperendemic foci, conducive to the emergence and transmission of drug-resistant strains. Summary The deepening of current knowledge on leprosy reservoirs, transmission, and therapeutic issues, with the One Health approach and the help of molecular biology, will allow a better understanding and management of the public health issues and challenges related to leprosy in Amazonia.

One Health and Hansen’s disease in Brazil

“…Eradication (rather than elimination) is almost certainly not feasible at any point in time for environmental and sylvatic mycobacteria. However, the mention of zoonotic transmission is a welcome addition to global Hansen's disease strategy, and we agree that research is needed, ideally directed from within endemic countries which have zoonotic reservoirs [32].…”

“…A better understanding of pathways to infection, including that these might not be from person to person, is also important in destigmatising disease. Brazil has not only ample scientific capacity to conduct such research and build the necessary evidence base [4], but is also well placed to collaborate with neighboring countries where zoonotic transmission presents a barrier to the elimination of Hansen's disease from endemic foci [32].…”

Susceptibility and resistance in leprosy: Studies in the mouse model

“…Numerous RT‐PCR reagents 15 necessary to probe the model for clues to leprosy pathogenesis have been developed as well. Armadillos naturally infected with M. leprae are found in the Gulf Coast area of the United States and in other parts of the Americas, 16,17 and their role as reservoir hosts for transmission of leprosy to humans has been documented 18‐20 …”

Dynamical Analysis and Design of Computational Methods for Nonlinear Stochastic Leprosy Epidemic Model

“…In 2009, Koba et al analyzed the trends and patterns of native leprosy in Japan [14]. However, in the countries of the Amazon region, not until 2020 when Schaub et al in [15] demonstrated the prevalence of distinct features of leprosy among humans and animal reservoirs. Kumar et al, in 2007, came out with a survey of leprosy disease among non-family contacts (NFC) and the family contacts (FC) of patients in Agra, India [16], while Fischer et al, in 2008, assessed the local distribution of leprosy cases in Bangladesh during 15-years of disease control program in Bangladesh [17].…”