- Award ID(s):
- 2011147
- NSF-PAR ID:
- 10439487
- Date Published:
- Journal Name:
- Environmental Research Letters
- Volume:
- 17
- Issue:
- 11
- ISSN:
- 1748-9326
- Page Range / eLocation ID:
- 114041
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Reisen, William (Ed.)Abstract The incidence of tick-borne diseases has increased in recent decades and accounts for the majority of vector-borne disease cases in temperate areas of Europe, North America, and Asia. This emergence has been attributed to multiple and interactive drivers including changes in climate, land use, abundance of key hosts, and people’s behaviors affecting the probability of human exposure to infected ticks. In this forum paper, we focus on how land use changes have shaped the eco-epidemiology of Ixodes scapularis-borne pathogens, in particular the Lyme disease spirochete Borrelia burgdorferi sensu stricto in the eastern United States. We use this as a model system, addressing other tick-borne disease systems as needed to illustrate patterns or processes. We first examine how land use interacts with abiotic conditions (microclimate) and biotic factors (e.g., host community composition) to influence the enzootic hazard, measured as the density of host-seeking I. scapularis nymphs infected with B. burgdorferi s.s. We then review the evidence of how specific landscape configuration, in particular forest fragmentation, influences the enzootic hazard and disease risk across spatial scales and urbanization levels. We emphasize the need for a dynamic understanding of landscapes based on tick and pathogen host movement and habitat use in relation to human resource provisioning. We propose a coupled natural-human systems framework for tick-borne diseases that accounts for the multiple interactions, nonlinearities and feedbacks in the system and conclude with a call for standardization of methodology and terminology to help integrate studies conducted at multiple scales.more » « less
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The range of hosts a pathogen can infect is a key trait influencing human disease risk and reservoir host infection dynamics. Borrelia burgdorferi sensu stricto (Bb), an emerging zoonotic pathogen, causes Lyme disease and is widely considered a host generalist, commonly infecting mammals and birds. Yet the extent of intraspecific variation in Bb host breadth, its role in determining host competence and potential implications to human infection remain unclear. We conducted a long-term study of Bb diversity, defined by the polymorphic ospC locus, across white-footed mice, passerine birds, and tick vectors leveraging long-read amplicon sequencing. Our results reveal strong variation in host breadth across Bb genotypes, exposing a spectrum of genotype-specific host-adapted phenotypes. We found support for multiple niche polymorphism maintaining Bb diversity in nature and little evidence of temporal shifts in genotype dominance, as would be expected under negative frequency-dependent selection. Passerine birds support the circulation of several human invasive strains in the local tick population and harbor greater Bb genotypic diversity compared to white-footed mice. Mouse-adapted Bb genotypes exhibited longer persistence in individual mice compared to non-adapted genotypes and infection communities infecting individual mice preferentially became dominated by mouse-adapted genotypes over time. We posit that intraspecific variation in Bb host breadth and specificity helps maintain overall species fitness in response to transmission by a generalist vector. Because pathogen genotypes vary in host breadth and result in diverse human disease manifestations, our findings indicate that a more nuanced definition of ‘host competence’ incorporating local genotype frequency is warranted.more » « less
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