Abstract
ABSTRACTOBJECTIVE To perform both space and space-time evaluations of visceral leishmaniasis in humans in the state of Sao Paulo, Brazil.METHODS The population considered in the study comprised autochthonous cases of visceral leishmaniasis and deaths resulting from it in Sao Paulo, between 1999 and 2013. The analysis considered the western region of the state as its studied area. Thematic maps were created to show visceral leishmaniasis dissemination in humans in the municipality. Spatial analysis tools Kernel and Kernel ratio were used to respectively obtain the distribution of cases and deaths and the distribution of incidence and mortality. Scan statistics were used in order to identify spatial and space-time clusters of cases and deaths.RESULTS The visceral leishmaniasis cases in humans, during the studied period, were observed to occur in the western portion of Sao Paulo, and their territorial extension mainly followed the eastbound course of the Marechal Rondon highway. The incidences were characterized as two sequences of concentric ellipses of decreasing intensities. The first and more intense one was found to have its epicenter in the municipality of Castilho (where the Marechal Rondon highway crosses the border of the state of Mato Grosso do Sul) and the second one in Bauru. Mortality was found to have a similar behavior to incidence. The spatial and space-time clusters of cases were observed to coincide with the two areas of highest incidence. Both the space-time clusters identified, even without coinciding in time, were started three years after the human cases were detected and had the same duration, that is, six years.CONCLUSIONS The expansion of visceral leishmaniasis in Sao Paulo has been taking place in an eastbound direction, focusing on the role of highways, especially Marechal Rondon, in this process. The space-time analysis detected the disease occurred in cycles, in different spaces and time periods. These meetings, if considered, may contribute to the adoption of actions that aim to prevent the disease from spreading throughout the whole territory of São Paulo or to at least reducing its expansion speed.
Highlights
It is estimated that 350 million people worldwide are under risk of acquiring leishmaniasis in its various clinical forms, and two million cases are expected to occur every yeara
The visceral leishmaniasis cases in humans, during the studied period, were observed to occur in the western portion of Sao Paulo, and their territorial extension mainly followed the eastbound course of the Marechal Rondon highway
These meetings, if considered, may contribute to the adoption of actions that aim to prevent the disease from spreading throughout the whole territory of São Paulo or to at least reducing its expansion speed
Summary
It is estimated that 350 million people worldwide are under risk of acquiring leishmaniasis in its various clinical forms, and two million cases are expected to occur every yeara. In the Americas, the most serious form of the disease is visceral leishmaniasis, which occurs in Central and South America, with most cases being notified in Brazilb. It is an anthropozoonosis whose agent is Leishmania (Leishmania) infantum chagasi, whose main vector is Lutzomyia longipalpis, and whose main reservoir is the household dog. In the state of Sao Paulo, the time series of visceral leishmaniasis cases was observed to start in 1999, having the western region as its gateway and spreading to other regions, a process that is still in progress[7]. Better understanding this process and identifying its determining factors may facilitate the adoption of effective surveillance and control initiatives, preventing visceral leishmaniasis from spreading throughout Sao Paulo’s whole territory, or, at least, reducing its expansion speed
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