Perfil sorológico de Rickettsia spp. e identificação de carrapatos parasitando humanos na Amazônia Oriental: Uma região silenciosa para Febre Maculosa Brasileira

Abstract

Introduction: Rocky Mountain Spotted Fever (SF) is an infectious disease of varying severity caused by bacteria of the Rickettsia genus, primarily Rickettsia parkeri and Rickettsia rickettsii. While human infections with R. parkeri are considered non-lethal, infection with R. rickettsii, when untreated, can have a case fatality rate exceeding 80%. In Brazil, seroepidemiological data on Rickettsia spp. infection in humans are still scarce, being practically nonexistent in the Amazon biome. Furthermore, little is known about the ticks that parasitize humans in this region, which harbors a high diversity of tick species. Objective: The present study aimed to detect the presence of anti-Rickettsia spp. antibodies in humans and to identify ticks parasitizing people in the Amazon biome. Results: 341 human serum samples were analyzed, of which 42% (145 samples) reacted with at least one species of the Rickettsia genus. Among these reactive samples, 47% (68) came from the municipality of Imperatriz, 31% (45) from Açailândia, and 22% (32) from São Luís. In Imperatriz, three species of the genus Rickettsia were identified in humans: Rickettsia rhipicephali, Rickettsia amblyommatis, and Rickettsia bellii. In Açailândia, R. amblyommatis and R. bellii were determined. No Rickettsia species were determined in the samples from São Luís. Furthermore, 105 ticks parasitizing humans were collected in the Amazon biome, mainly belonging to the genus Amblyomma (101 specimens), in addition to one specimen of the genus Rhipicephalus. Conclusion: This study demonstrates that both humans and animals in the Amazon biome are in contact with rickettsiae belonging to the Spotted Fever Group, with emphasis on R. amblyommatis. It also highlights the population's continued exposure to ticks that are potential vectors of Rickettsia spp., especially those of the genus Amblyomma.