The ecology of Lyme borreliosis risk : interactions between lxodes ricinus, rodents and Borrelia burgdorferi sensu lato

Duijvendijk, Gilian van

doi:10.18174/390911

Cited by 1 publication

(1 citation statement)

References 153 publications

(352 reference statements)

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“…In contrast to our experiment, previous studies have shown Lyme disease hazard to be associated with higher densities of transmission hosts [ 25 , 58 ]. However, such an association requires enough vectors in the environment to transmit the pathogen effectively [ 59 ], whereas in our experimental situation, the plots with high densities of transmission hosts did not have deer, and therefore had few ticks to aid transmission.…”

Section: Discussioncontrasting

confidence: 99%

Experimental evidence for opposing effects of high deer density on tick-borne pathogen prevalence and hazard

et al. 2021

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Background Identifying the mechanisms driving disease risk is challenging for multi-host pathogens, such as Borrelia burgdorferi sensu lato (s.l.), the tick-borne bacteria causing Lyme disease. Deer are tick reproduction hosts but do not transmit B. burgdorferi s.l., whereas rodents and birds are competent transmission hosts. Here, we use a long-term deer exclosure experiment to test three mechanisms for how high deer density might shape B. burgdorferi s.l. prevalence in ticks: increased prevalence due to higher larval tick densities facilitating high transmission on rodents (M1); alternatively, reduced B. burgdorferi s.l. prevalence because more larval ticks feed on deer rather than transmission-competent rodents (dilution effect) (M2), potentially due to ecological cascades, whereby higher deer grazing pressure shortens vegetation which decreases rodent abundance thus reducing transmission (M3). Methods In a large enclosure where red deer stags were kept at high density (35.5 deer km−2), we used an experimental design consisting of eight plots of 0.23 ha, four of which were fenced to simulate the absence of deer and four that were accessible to deer. In each plot we measured the density of questing nymphs and nymphal infection prevalence in spring, summer and autumn, and quantified vegetation height and density, and small mammal abundance. Results Prevalence tended to be lower, though not conclusively so, in high deer density plots compared to exclosures (predicted prevalence of 1.0% vs 2.2%), suggesting that the dilution and cascade mechanisms might outweigh the increased opportunities for transmission mechanism. Presence of deer at high density led to shorter vegetation and fewer rodents, consistent with an ecological cascade. However, Lyme disease hazard (density of infected I. ricinus nymphs) was five times higher in high deer density plots due to tick density being 18 times higher. Conclusions High densities of tick reproduction hosts such as deer can drive up vector-borne disease hazard, despite the potential to simultaneously reduce pathogen prevalence. This has implications for environmental pathogen management and for deer management, although the impact of intermediate deer densities now needs testing. Graphical abstract

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Section: Discussioncontrasting

confidence: 99%