Visceral leishmaniasis epidemiologic evolution in timeframes, based on demographic changes and scientific...

Visceral leishmaniasis (VL) is a disease of chronic evolution which could be uniformly fatal, if left untreated. Human VL was first described in the Americas in 1913 and in 1936 in Brazil. The number of VL cases in Brazil is increasing steadily in the last three decades. Medical literature highlights this change in the disease epidemiology as a recent urbanization phenomenon, with most of the cases occurring in large cities since 1981, different to that observed previously, like a typical rural endemic. The aim of this study was to create a narrative review of the evolution of VL epidemiology since its first description in Brazil. To describe the process of urbanization of VL, timeframes were created historically consistent with the scientific and public health knowledge obtained about the VL and the demographics changes in Brazil, especially considering the extensive migratory movements in the country due to political or economic events. The first phase of VL was the decades of 30-50 when industrialization triggered internal migration process from countryside to the cities; during this period VL was studied for the first time and described as a rural endemic disease with no relevance to public health. Until the second phase, between the 50s and 80s of the 20th century, demography was characterized by expansion of immigration to the large cities and increase in population density in the suburbs with poor living standards. In this period, there was an advancement in the knowledge of the transmission of the disease being described as the first case acquired in the urban environment. The third phase was characterized by the explosion of cases in Brazilian cities and consolidation of urban endemic transmission. The possibility of urban transmission has been known since the 50s; however, the current phenomenon was due to the creation of ideal conditions for the establishment of transmission cycle in Brazilian cities.