Abstract
There are several gaps in our knowledge on the origin and spread ofLeishmania (Viannia) braziliensis, an etiological agent of cutaneous and mucocutaneous or American tegumentary leishmaniasis, to different biomes, hosts, and vectors, with important epidemiological implications, including the possible existence of an anthroponotic component. Historical, biological, and epidemiological evidence suggests thatLeishmania (V.) braziliensisand its variants were preexistent in Amazonia with great genetic variability, where they dispersed with less variability to other regions (clonal expansion). During pre-Columbian times the parasite may have been transported by migrating humans and probably also their dogs, from western Amazonia to the high inter-Andean valleys and from there to other regions of South America. The same thing could have happened later, in the same way, when it spread to non-Amazonian regions of Brazil and other countries of South and Central America, between the late 19th and early 20th centuries, during the so-called Rubber Boom and construction of the Madeira-Mamoré Railway in the Brazilian Amazon, by migrant workers who later returned to their places of origin, transporting the agent. The parasite’s dispersal in genetic correlated clusters, involving unexpectedly distinct ecosystems in Brazil (Amazonian, Cerrado, Caatinga and Atlantic Forest biomes), has continued until the present through human displacement. The infection of certain species of domestic, synanthropic and even wild animals, could be secondary to anthropogenic introduction ofL. (V.) braziliensisin new environments. We admit the same phenomena happening in the probable transference ofLeishmania infantum(visceral leishmaniasis), and of Yersinia pestis (plague) from the Old world to the New world, generating domestic and wild enzotic cycles from these agents. These assumptions associated with human infections, chronicity and parasite persistence with possibility of recovery ofLeishmaniain peripheral blood, skin and scars of cured or asymptomatic patients, (that may provide an alternative blood meal), along with the sand flies’ adaptation to the peri-domicile and the high susceptibility of domestic dogs, horses, mules and cats to the parasite, can reinforce the evidence of anthropogenic spread ofL. (V.) braziliensis.
Highlights
Leishmania (Viannia) braziliensis is the most important etiological agent in Brazil and in the set of Andean countries that includes Amazonian areas, Venezuela, Colombia, Ecuador, Peru, and Bolivia, producing mucosal lesions, with predominantly rural and peri-domiciliary transmission [1].In Brazil, L. (V.) braziliensis is distributed throughout the country, with numerous vector species involved in the transmission and an incidence of 11.9 cases per 100,000 inhabitants [2, 3]
We used scientific and historical sources mostly published in scientific articles and some in specialized books from 1908 to 2021, in Brazil and in neighboring countries, in combination with our own experience and personal observations in over 40 years working in the field of leishmaniasis in different geographic areas of Brazil and other South American countries
The enormous biodiversity of the Amazonia and the wide diversity of Leishmania species from sub-genus Viannia suggest that this is the geographic origin of this sub-genus, and that species such as L. (V.) braziliensis have been circulating in the region for a long time, maybe since antiquity
Summary
Leishmania (Viannia) braziliensis is the most important etiological agent in Brazil and in the set of Andean countries that includes Amazonian areas, Venezuela, Colombia, Ecuador, Peru, and Bolivia, producing mucosal lesions, with predominantly rural and peri-domiciliary transmission [1]. Outside the Amazonia, sylvatic cycles of L (V.) braziliensis in natural foci of occurrence have still not been defined [8, 12,13,14] This agent is found in altered environments in rural and peri-domiciliary cycles involving various sandfly species like Lu. intermedia, Lu. whitmani, Lu. migonei, and Lu. neivai, to the South, and the Verrucarum group in the Andean countries. Domestic dogs are highly susceptible to experimental infection and are frequently found naturally infected in Brazil, Argentina, Peru, Bolivia, Ecuador, Colombia, and Venezuela [1, 8, 19,20,21] In these animals, the lesions occur on hairless areas, which are more accessible to the insect vectors, like the snout, ears, and scrotum [8, 13, 19]. We have interpreted this finding as a possible co-evolutionary adaption of the parasite, with humans becoming an important secondary reservoir [4]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
