Open access publications in the SLU publication database

Abstract

Ungulates play a central role in the life cycle of Ixodes ricinus, an important vector of tick-borne pathogens, and several ungulate species are increasingly common across Europe. I investigated the role of these different species in the spread of I. ricinus-borne pathogens. Through a meta-analysis, I quantified the relative importance of ungulate species in the transmission of Anaplasma phagocytophilum. Furthermore, through field studies, I compared the contribution of each species to the number of ticks and the transmission of A. phagocytophilum and Borrelia burgdorferi sensu lato (s.l.) by quantifying tick burdens, relative ungulate densities, vegetation structure and (infected) questing tick density. My studies indicated that Ticking off the ungulate box – the role of different ungulate species in the transmission of tick-borne pathogens deer contributed more to the spread of tick-borne pathogens than wild boar (Sus scrofa), and fallow deer (Dama dama) more than the other deer species. I then modelled how changing an ungulate community composition affects the establishment of pathogens, expressed by the reproduction number R0. High density of fallow deer along with low density of roe deer (Capreolus capreolus) resulted in a higher R0 of the zoonotic A. phagocytophilum ecotype 1, and a lower R0 of the nonzoonotic ecotype 2. The effects of ungulates on the R0 of B. afzelii and B. garinii were negligible. My thesis thus suggests that different deer species likely vary in their effect on the circulation of various tick-borne pathogens. Ungulate management, as a tool to mitigate public and veterinary health risk, should therefore not approach ungulates as one homogenous group, but depending on the pathogen, take note of potentially different roles that ungulate species may play.