A retrospective study regarding the prevalence of tick-borne pathogens in Ixodes ricinus ticks collected from companion animals in the Netherlands over the past 10 years through the Tickbusters survey

Abstract

Background Almost 900 different tick species have been described worldwide. In the Netherlands, Ixodes ricinus is the predominant tick. Adult ticks have a broad host range, including larger mammalian species such as cattle, sheep and goats, dogs, and in particular wild ungulates, e.g. deer. Ixodes ricinus is vector and reservoir of Borrelia, Anaplasma, Ehrlichia, Babesia and Rickettsia species as well as for viral pathogens such as tick-borne encephalitis virus.

Methods Over the past 10 years (2006-2015) a large number of ticks has been collected from dogs and cats in the Netherlands as part of the Tickbusters survey. A random selection of 40 I. ricinus ticks collected during the peak of the tick season in May of each year was made and tested by PCR and Reverse Line Blot (RLB) hybridization to perform a retrospective screening of tick-borne pathogens. In addition, ticks submitted during the 2016 campaign were identified to species, stage and sex. All ticks were individually numbered and stored in 70% ethanol until further use.

Results Several pathogens were found in I. ricinus, especially Borrelia burgdorferi sensu lato, Borrelia afzelii and Borrelia garinii and several Rickettsia spp. Other pathogens were Babesia venatorum (sp EU1), Babesia major, Neoehrlichia mikurensis and Anaplasma phagocytophilum. The number of co-infected ticks ranged between 0 and 5 depending on the year. During the 2016 campaign, 1867 ticks were received between early March until the end of June from the Netherlands and Belgium. Of these, 57,8% originated from dogs and 42,2% were removed from cats. I. ricinus was the most abundant species identified.

Conclusion There were no significant differences in the prevalence of tick-borne pathogens in I. ricinus, collected during the month of May on dogs and cats during the past 10 years in the Netherlands. Although no clear up or downward trend was identified, the results show that the significant infection rates ranging between 10% and 30% are likely to be retained the tick population and continue to pose a threat to companion animals and humans in the foreseeable future.