First detection of spotted fever group rickettsiae in Ixodes ricinus from Italy

Abstract

Ixodes ricinus from Italy were examined for the first time to detect whether rickettsiae were present. Using molecular methods, we detected three different spotted fever group rickettsiae, including Rickettsia helvetica. Our results raise the possibility that bacteria other than R. conorii are involved in rickettsial diseases in Italy.

Figure 1

Location of Ixodes ricinus collection sites and detection of spotted fever group rickettsiae. 1). Trentino Province. Dots represent places where ticks were not found to have rickettsiae; different shapes represent the places where IrITA1 (Terlago, Denno, Vervó), IrITA2 (Molina di Ledro, Drena) and IrITA3 (Drena) were detected. In Feltre (2; Veneto Region) only IrITA1 was detected, while in Parco Nazionale delle Foreste Casentinesi (3; Toscana Region) only IrITA2 was detected.

Figure 2

Phylogenetic analyses of rickettsiae based on gltA (A), 17 kDa (B) and ompA (C). Based on analyses in Modeltest 3.06, the models of substitution chosen for analysis in Treepuzzle 5.0 were TrN+G for gltA and 17kDa, and HKY+G for ompA. GenBank accession numbers for each sequence, including those found in this study (IrITA1-3), are shown adjacent to each strain. Numbers near each node represent quartet puzzling support values. Scale bars represent number of inferred substitutions at each site.