Ticks and associated pathogens collected from domestic animals in the Netherlands

Following an outbreak of autochthonous canine babesiosis in the Netherlands, a request made to veterinarians and the public to collect ticks from companion animals resulted in 4298 ticks submitted between July 2005 and October 2006 to our center. Ticks were identified as Ixodes ricinus adults (2907/4298, 67.6%), Ixodes sp. nymphs (529/4298, 12.3%) and Ixodes sp. larvae (385/4298, 9.0%), I. hexagonus adults (328/4298, 7.6%), Dermacentor reticulatus (72/4298, 1.7%), and several other exotic tick species such as Amblyomma flavomaculatum (formerly Aponomma flavomaculatum), Hyalomma marginatum rufipes, Rhipicephalus sanguineus, and R. turanicus (55/4298, 1.3%). Eight localities were surveyed for the presence of local D. reticulatus, a tick not indigenous to the Netherlands, based on multiple submissions of D. reticulatus ticks from these areas. D. reticulatus was collected from the vegetation in six of these localities, confirming the presence of populations of this tick in the Netherlands. Adult I. ricinus (n=251), I. hexagonus (n=237), and D. reticulatus (n=344) ticks were selected at random and subsequently screened by polymerase chain reaction (PCR) and reverse line blot (RLB) hybridization for the presence of Borrelia, Babesia, Theileria, Anaplasma, Ehrlichia, and Rickettsia species. I. ricinus ticks were infected with Rickettsia helvetica (24.7%), spirochetes belonging to the Borrelia burgdorferi sensu lato group (7.2%), the Ehrlichia-like "Schotii" variant (2.4%), Anaplasma phagocytophilum (1.6%), Babesia sp. (EU1) (1.2%), Babesia divergens (0.4%), and Babesia microti (0.4%). A. phagocytophilum (5.9%) and R. helvetica (0.8%) were also detected in adult I. hexagonus ticks. Spotted fever group Rickettsiae, previously reported as Rickettsia sp. DnS14/RpA4 (14.0%), and Borrelia burgdorferi sensu lato (0.3%) were detected in the D. reticulatus ticks, which appeared to be free from B. canis infection. We concluded that a much broader spectrum of ticks and tick-borne pathogens is present in the Netherlands than previously thought, including several potential zoonotic pathogens.