Prevalência de anticorpos contra rickettsias do grupo da febre maculosa em humanos, cães e equinos e identificação molecular de Rickettsia spp em carrapatos na região Norte do Paraná

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Brazilian Spotted Fever is a disease transmitted to humans and animals by Amblyomma spp ticks and the most important agent responsible for this disease is R. rickettsii that belongs to the Rickettsiales order and Rickettsiaceae family. The objective of this paper was to study the epidemiology of Brazilian Spotted Fever rickettsias in two rural areas and in horse farms located in the Northern Paraná state. Serums of humans, dogs and horse were collected in two rural areas. In the first area, located in Alvorada do Sul, were sampled 83 dogs, 18 horses and 88 humans and, in the second area, located in Arapongas, were sampled 90 dogs, 18 horses and 138 humans. From the six horse farms located in Cambé, Guaraci, Santa Fé and Londrina were collected a total of 273 horse blood samples. These areas were not considered endemic for BSF. The animal and human sera were submitted to the Indirect Immunofluorescence assay (IFI) with R. rickettsii and R. parkeri antigens, considering as positive titles ≥ 64. Ticks collected from horses and dogs were submitted to Polymerase Chain reaction (PCR). In Alvorada do Sul, 24% and 16.1% of humans, 55.6% and 22.2% of horses and, 22.9% and 18,1% of dogs were seropositive for R rickettsii and R. parkeri, respectively. In Arapongas, 9.4% and 4.3% of the humans, 5.6% and 5.6% of horses and, 13.3% and 12.2% of the dogs were seropositive for R. rickettsii and, for R. parkeri antigens, respectively. Four sera samples of dogs showed titles at least four-folds greater for R. parkeri and just one sample of dog was greater for R. rickettsii. Six horses and nine humans showed titles four times greater for R. rickettsii. No samples of horses and humans suggested R. parkeri. The ticks species identified in our study were A. cajennense in horses and dogs and A. ovale in dogs. The PCR detected seven positives ticks with gltA primer and the gene sequencing showed similarity with R. bellii. From the total of 273 sera, 15 (5.5%) sera reacted against R. rickettsii and 5 (1.8%) to R. parkeri. It was found seropositive animals in five of six farms studied. The rates of seropositive animals varied from 0% to 13%, and only in one farm all the horses were seronegatives. The titers varied from 64 to 518, with final titer being detected in four samples. Nine of all positive animals reacted to R. rickettisii four-fold higher than R. parkeri, which indicates the circulation of Rickettssia spp homologue to R. rickettsii in the horse farms studied. This study suggests the presence of some rickettsia very close to R. rickettsii infecting horses in horse farms in the Northern Parana state, Brazil. Additionally, the presence of homologues antibodies to R. parkeri in dogs, and homologues antibodies to R. rickettsii antigen in horses and humans shows a potential risk for human BSF in the studied area.

ASSUNTO(S)

brazilian spotted fever rickettsia - epidemiologia carrapato como transmissor de doenças febre maculosa brasileira amblyomma ticks as carriers of disease

ACESSO AO ARTIGO

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