Detection of antibodies to tick salivary antigens among patients from a region of Spain.

With a view to determine which tick species bite humans most frequently in the province of Soria (Spain) and to know whether these species act as vectors of Rickettsia conorii and/or Borrelia burgdorferi, we analysed the presence of antibodies against salivary proteins of several tick species and of antibodies against R. conorii and B. burgdorferi sensu lato in 102 samples of serum. The sera were collected from 63 patients who were treated for tick bites at the health services of the Soria Health Area. Thirty-nine percent of the patients displayed antibodies against Dermacentor marginatus; 21% against Ixodes ricinus, and 6% against Rhipicephalus sanguineus. IgM antibodies against R. conorii were found in 15 patients, but none of the patients included in the study displayed IgG/IgM Abs against B. burgdorferi sensu lato. In 30% of the patients bitten by I. ricinus and in 24% bitten by D. marginatus, antibodies against R. conorii were found. None of the patients who had been bitten by R. sanguineus expressed antibodies against this pathogen. The results obtained here suggest that D. marginatus and I. ricinus are the main vectors of the spotted fever group rickettsiae in our environment and that the role of R. sanguineus in the transmission of these rickettsiae is debatable.