Survey of rickettsiae from the Spotted Fever Group causing infections in humans, equines, canines and in different developmental stages of Amblyomma cajennense, from an endemic area of the State of São Paulo, Brazil / Pesquisa de infecção por riquétsias do grupo da Febre Maculosa em humanos, eqüídeos, caninos e em diferentes estádios de vida de Amblyomma cajennense, provenientes de uma área endêmica do Estado de São Paulo

AUTOR(ES)

Mauricio Claudio Horta

DATA DE PUBLICAÇÃO

2002

RESUMO

Spotted fever is an emergent zoonosis caused by Rickettsia from the Spotted Fever Group. This study was designed to indirectly detect the human and animals infection by rickettsiae, and to directly detect the Amblyomma cajennense tick infection. The samples were collected at the Pedreira County, an endemic region of the State of São Paulo. The indirect imunofluorescence assay was positive for 31.2 % of canine and for 77.3% of equine examined sera. No human serum was positive by the use of this serological tests. In order to confirm the adult tick natural infection, it was used the hemolymph test, which showed to be unsatisfactory. The larvae, nymph and adult tick rickettsiae detection was performed by the use of the polymerase chain reaction (PCR). The PCR resulted on the amplification of a 230 bp fragment of the gene encoding the17 kDa protein, in adults (4.7%) and larvae (1.1%) only. It was not possible to amplify any other tested gene fragment (citrate synthase, OmpA and OmpB). The PCR amplified products from two adult ticks and from four larvae were sequenced, and presented 100% of similarity with Rickettsia felis and from 99,4% to 100% of similarity to Rickettsia rickettsii, Rickettsia conorii, Rickettsia parkeri and Rickettsia peacockii, respectively. The rickettsia detection in non-fed larvae confirms the occurrence of the rickettsiae transovarian transmission in A. cajennense specie. The high identity observed among the present studied rickettsiae and the above cited rickettsia species suggests the presence of these bacteria in Pedreira County. However, once the sequences of bases of the studied amplified DNA fragment did not allow the differentiation among the SFG rickettsiae, further studies are necessary.

ASSUNTO(S)

rickettsia spotted fever amblyomma cajennense amblyomma cajennense febre maculosa rickettsia carrapato tick

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