Leptospiras nas Américas de 1930-2017: um estudo sobre diversidade de sorovares patogênicos e nicho ecológico.

Abstract

Leptospirosis is a public health problem, and it is among the world’s neglected diseases. It is a zoonotic infectious disease caused by bacteria of the genus Leptospira, which has a high diversity of serovars and reservoirs. Therefore, it is essential to know the geographic distribution of serovars and their ecological niches. This general objective of this study was characterizing the diversity of pathogenic leptospires in the Americas and its relation to their ecological niches and impact on the transmission of leptospirosis. We responded to this objective through three articles. Article 1: The objective was to characterize the geographic distribution of pathogenic leptospire serovars in the Americas, based on a systematic review between 1930 and 2017, where a total of 1310 articles were identified. After evaluation by inclusion and exclusion criteria based on title and abstract review, 750 articles remained. Finally, the evaluation of the full text and analyzed of 283 articles, of which 69 were performed in humans, 86 in wild animals and 182 in domestic animals, most of them performed in Brazil (104), in rural environments, being the most frequent serovars: the Icterohaemorrhgiae , Pomona, Canicola and Grippotyphosa . The results found point to a concentration of georeferenced points in Latin America, especially in Brazil. In addition, studies that deepen the environmental characteristics should be explored. Article 2: This study aims to analyze the prevalence of leptospirosis in the Americas, from a systematic review with meta -analysis, in the period from 1930 to 2017, carried out on six research platforms: PubMed , Web of Science, Scopus, Lilacs , Embase and Cochrane. Articles (77) were found in all countries of the Americas; North (11, 14%), Central (9;11%) and South (42; 53%); most from rural areas (12;15%) and 53 (67.9%) articles are from 2000 to 2017. The overall average prevalence of leptospirosis across all articles corresponds to 28% (0.23-0.32) 95% CI. The countries with the highest prevalence were the USA (41%), Brazil (21%) and Colombia (29%). The most frequent serovars found were: Icterohaemorrageae (43;55%), Canicola (35;45%), Pomona (28;36%) and Grippotyphosa (26;33%). There is a variability of Leptospira species and serovars heterogeneously distributed throughout the Americas, with high prevalence in some countries, which shows that it is necessary to undertake actions to control this disease that is still neglected in the world. Article 3: The objective is to investigate the current geographic distribution and the impact of different climate change scenarios on the potential geographic distribution of pathogenic leptospiral serovars circulating in the Americas. Information related to serovars including location and reservoir was extracted from articles identified through a systematic review from 1930-2017. Environmental variables were used as predictors in ecological niche modeling. Analyzes were based on the scale of leptospirosis transmission in time and space, considering pathogenic serovars, considering RCP 4.5 and RCP8.5, for the years 2050 and 2070. The results point to a potential conservation of leptospirosis transmission in scenarios of global climate change, mainly in Central and South America. And finally, it is believed that based on the findings found, it will be possible to mitigate environmental conservation actions to control and reduce the consequences of future temperature changes, which are important variables for the transmission of leptospirosis.