engleski

Molecular identification of flea-transmitted Rickettsia felis-like bacteria in Haemaphysalis sulcata ticks collected from domestic animals in southern Croatia

Ticks of the genus Haemaphysalis are rarely associated with rickettsiae. Rickettsia canada, R. rickettsii, R. felis and some new uncultured rickettsiae has been described in Hemaphysalis ticks. Description of R. canada and R. felis from ticks showed some ambiguous results, namely, the uncertain phylogenetic position of R. canada and the fact that R. felis is primarily vectored by fleas. However, H. sulcata ticks collected in southern Croatia from 2000 to 2002 were found to be rather highly infected with rickettsiae using molecular techniques. In autumn 2000, spring 2001 and 2002, a total of 101 adult H. sulcata ticks were collected from domestic animals (sheep, goat) in southern Croatia. DNA was extracted from individual ticks. Each tick was tested for the presence of rickettsiae by using PCR assays to amplify complete gltA gene and a portion of 17 kDa, ompA and ompB genes. With an exception of ompA gene which could not be amplified, the gene sequence determination of all other genes allowed us to identify the detected rickettsiae. The rickettsia was similar to R. felis (R. sp. California-2) in 95.5 %, 95.2 % and 98 % regarding the complete gltA, partial 17kDa and ompB genes, respectively. Phylogenetic tree inferred with PAUP program using distance analysis, HKY85 model and 1000 bootstraps confirmed clustering of rickettsia from H. sulcata ticks with R. felis within the spotted fever group of rickettsiae. R. felis was previously detected in 4 H. flava ticks in Japan. However, the authors were not certain if the rickettsia temporarily propagated in the tick from the animal infected by the cat flea. On the contrast, R. felis-like bacteria from H. sulcata collected in southern Croatia was continuously detected in this tick species with the infection rate varying from 19.6 % to 26 % depending on the time of the year.

molecular identification; ticks; Haemaphysalis sulcata; Rickettsia felis

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