Identity of Ehrlichial DNA Sequences Derived from Ixodes ricinus Ticks with Those Obtained from Patients with Human

human granulocytic ehrlichiosis (HGE) by using PCR assays based on the 16S rRNA gene. Three (3.2%) of 93 ticks were found to contain granulocytic ehrlichiae. Nucleotide sequences of portions of the bacterial groESL heat shock operon amplified from these ticks were identical or nearly (99.8%) identical to those previously determined for human patients with HGE from Slovenia, providing additional evidence that the ticks were infected with the HGE agent. This study identified I. ricinus as the likely vector for these ehrlichial pathogens of humans in this part of Europe. In 1996, four cases of human granulocytic ehrlichiosis (HGE) were identified near Ljubljana, Slovenia (5, 8). All four patients reported exposure to ticks, and none had traveled outside of Slovenia within the putative incubation period. The aim of this study was to collect Ixodes ricinus ticks from the Ljubljana area to determine if they were infected with an ehrlichial species and, if so, to assess the DNA sequence homologies between amplicons derived from ticks with those obtained from three of the patients (one patient developed antibodies to the HG