Abstract
BackgroundSeveral ungulate species are feeding and propagation hosts for the tick Ixodes ricinus as well as hosts to a wide range of zoonotic pathogens. Here, we focus on Anaplasma phagocytophilum and Borrelia burgdorferi (s.l.), two important pathogens for which ungulates are amplifying and dilution hosts, respectively. Ungulate management is one of the main tools to mitigate human health risks associated with these tick-borne pathogens. Across Europe, different species of ungulates are expanding their ranges and increasing in numbers. It is currently unclear if and how the relative contribution to the life-cycle of I. ricinus and the transmission cycles of tick-borne pathogens differ among these species. In this study, we aimed to identify these relative contributions for five European ungulate species.MethodsWe quantified the tick load and collected ticks and spleen samples from hunted fallow deer (Dama dama, n = 131), moose (Alces alces, n = 15), red deer (Cervus elaphus, n = 61), roe deer (Capreolus capreolus, n = 30) and wild boar (Sus scrofa, n = 87) in south-central Sweden. We investigated the presence of tick-borne pathogens in ticks and spleen samples using real-time PCR. We determined if ungulate species differed in tick load (prevalence and intensity) and in infection prevalence in their tissue as well as in the ticks feeding on them.ResultsWild boar hosted fewer adult female ticks than any of the deer species, indicating that deer are more important as propagation hosts. Among the deer species, moose had the lowest number of female ticks, while there was no difference among the other deer species. Given the low number of infected nymphs, the relative contribution of all ungulate species to the transmission of B. burgdorferi (s.l.) was low. Fallow deer, red deer and roe deer contributed more to the transmission of A. phagocytophilum than wild boar.ConclusionsThe ungulate species clearly differed in their role as a propagation host and in the transmission of B. burgdorferi and A. phagocytophilum. This study provides crucial information for ungulate management as a tool to mitigate zoonotic disease risk and argues for adapting management approaches to the local ungulate species composition and the pathogen(s) of concern.Graphic abstract
Highlights
Several ungulate species are feeding and propagation hosts for the tick Ixodes ricinus as well as hosts to a wide range of zoonotic pathogens
Contribution of ungulate species as propagation hosts Of the 261 ungulates of which the whole carcass was checked for ticks, 119 animals were infested with 515 non-feeding males in total (Additional file 1: Table S3)
Based on the selected models (Additional file 1: Table S5), all four deer species had a higher infestation prevalence of females than wild boar, and there was no difference among the deer species in terms of the infestation
Summary
Several ungulate species are feeding and propagation hosts for the tick Ixodes ricinus as well as hosts to a wide range of zoonotic pathogens. Many areas in Europe currently host a higher diversity of ungulate species than during the recent past [6] This increase of wild ungulates has allowed their ectoparasites, such as the tick species Ixodes ricinus, to increase in densities and expand their ranges [7], leading to an increase in the prevalence of tick-borne zoonotic pathogens, such as Anaplasma phagocytophilum and Borrelia burgdorferi (s.l.). Ungulates play a central role in the life-cycle of I. ricinus as feeding hosts, but most importantly as propagation hosts [8] It is poorly understood if and how ungulate species differ in terms of their relative contribution to the tick life-cycle and to the transmission of tick-borne pathogens. Data on certain common ungulate species, wild boar and fallow deer, are currently still scarce [8]
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