Detection of HGE agent-like Ehrlichia in Ixodes ricinus ticks in northern Italy by PCR

Little is known about the distribution of Human Granulocytic Ehrlichiosis (HGE) in Europe and even less is known in Italy, where no case of clinically documented HGE has been reported. In a previous study we reported the presence of Ehrlichia DNA in Ixodes ricinus ticks from Central Italy. By the use of an Ehrlichia-specific PCR we found that 24% of the ticks were positive. Furthermore, we demonstrated a simultaneous coinfection of the same tick by both, Borrelia burgdorferi and Ehrlichia phagocytophila. Since the Friuli-Venezia Giulia region (North-east of Italy) is endemic for Lyme borreliosis (LB) and the geographic distribution of HGE usually overlaps that of LB, we decided to carry out a survey concerning the presence of Ehrlichia spp. in a recreational area near Trieste where the presence of Lyme borreliosis and Borrelia burgdorferi sensu lato in ticks is well demonstrated. Ticks were analyzed in pools (because a low infection rate was expected): eleven samples out of 93 were found positive by Ehrlichia-PCR. Subsequent sequence analysis of some of the positive PCR products revealed a high homology with the HGE agent Ehrlichia (only one base substitution in almost 450 bp sequenced). These findings add new and interesting data on the Ehrlichia epidemiology in Italy. By now we have demonstrated the presence of two distinct granulocytic ehrlichiae in Italiyn ticks by the aid of a PCR-based analysis: Ehrlichia phagocytophila in Central Italy and an HGE-like Ehrlichia in the north-eastern Italy, in a region close to Slovenia where the first reported case of HGE in Europe occurred.