Detecção e caracterização molecular de rickettsias do grupo da febre maculosa em humanos, animais na interface silvestre/ urbana e ixodídeos procedentes do estado de Pernambuco

Abstract

Rickettsia spp. are bacteria of wide geographic distribution group capable of infecting humans and animals through ticks of the genus Amblyomma. Until now, it is known that Brazilian Spotted Fever is associated to three cycles of transmission according to vectors, hosts and the environments involved. The aim of this study was to detect and characterize molecularly rickettsiae of SF group in humans, synanthropic animals and ixodids from Pernambuco state. Blodd samples from 97 rodents (Rattus novergicus, Rattus rattus, Trichomys spp. and Cavea aperea) and 34 marsupials (Didelphis albiventris) were collected and the molecular characterization of Rickettsia spp. was performed using the Polymerase Chain Reaction. The data showed the frequency of 6.18% of positivity for rodents in Recife (1.03%), Camaragibe (1.03%), Itamaracá (2.06%) in the metropolitan region of Recife and Izacolândia (2.06%), Petrolina. However, no Rickettsia spp. was found in those marsupials. On the other hand, the first case of SF in the northeast region of Brazil was reported in a man of the Arcoverde County, but this patient may be infected at the Sertânia County, both places in Pernambuco State.The patient showed clinical signs suggestive of SF, and the infection was confirmed by Polymerase Chain Reaction and subsequent sequencing. From the confirmation of this case, an epidemiological investigation was carried out to collect ticks. Ticks collected from Canis familiaris and Euphractus sexcinctus, were classified as Rhipicephalus sanguineus sensu lato and Amblyomma pseudoconcolor, respectively. Of the total A. pseudoconcolor collected (90.9%) were positive to presence of Rickettsia spp., and no infected R. sanguineus s.l. was found. Genetic analysis based on five rickettsial genes showed that the detected strain is most closely related to Rickettsia amblyommatis, confirmed, for the first time, detected in Amblyomma pseudoconcolor In conclusion, this is the first report of infection of Rickettsia spp. in rodents and humans besides the first report of R. amblyommatis in A. pseudoconcolor in Pernambuco state, northeastern Brazil. The data obtained in this study suggest that small mammals can be an important role in maintaining, circulating and disseminating rickettsia inside and outside the natural focus. Finally the results point to this tick as a potential vector in the enzootic cycle of R. amblyommatis in Brazilian northeast.