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Globally, zoonotic vector-borne diseases are on the rise and understanding their complex transmission cycles is pertinent to mitigating disease risk. In North America, Lyme disease is the most commonly reported vector-borne disease and is caused by transmission of Borrelia burgdorferi sensu lato (s.l.) from Ixodes spp. ticks to a diverse group of vertebrate hosts. Small mammal reservoir hosts are primarily responsible for maintenance of B. burgdorferi s.l. across the United States. Never- theless, birds can also be parasitized by ticks and are capable of infection with B. burgdorferi s.l. but their role in B. burgdorferi s.l. transmission dynamics is understudied. Birds could be important in both the maintenance and spread of B. burgdorferi s.l. and ticks because of their high mobility and shared habitat with important mammalian reservoir hosts. This study aims to better understand the role of avian hosts in tick-borne zoonotic disease transmission cycles in the western United States. We surveyed birds, mammals, and ticks at nine sites in northern California for B. burgdorferi s.l. infection and collected data on other metrics of host community composition such as abundance and diversity of birds, small mammals, lizards, predators, and ticks. We found 22.8% of birds infected with B. burgdorferi s.l. and that the likelihood of avian B. burgdorferi s.l. infection was significantly associated with local host community composition and pathogen prevalence in California. Addition- ally, we found an average tick burden of 0.22 ticks per bird across all species. Predator and lizard abundances were significant predictors of avian tick infestation. These results indicate that birds are relevant hosts in the local B. burgdorferi s.l. transmission cycle in the western United States and quantifying their role in the spread and maintenance of Lyme disease requires further research.
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Incorporating phylogenetic metrics of biodiversity to refine Lyme disease risk models
Abstract Biodiversity has been linked to reduced disease transmission through the dilution effect process. Traditional ecological measures of biological diversity, such as species richness, are most commonly used to test for the dilution effect. However, such metrics of species diversity do not consider the evolutionary relationship between species, which has important implications for host immune processes and disease transmission. Phylogenetic diversity incorporates the evolutionary relationships of a wildlife community. Host reservoir competency is partly determined by their capacity to mount effective immune responses, which may be phylogenetically determined. As a result, phylogenetic diversity may be a better metric to evaluate the relationship between host diversity and disease transmission, given that closely related species may have more similar pathogen competencies than distantly related ones. Few studies have examined the relationship between phylogenetic diversity and disease transmission, particularly in vector‐borne transmission systems. This study seeks to quantify phylogenetic diversity in the western United States Lyme disease system, where the causal agentBorrelia burgdorferiis vectored by the western black‐legged tick,Ixodes pacificus.We empirically measured mammalian diversity and tick data over seven years. We collected data on ticks, host community, and infection prevalence withBorrelia burgdorferiand constructed generalized linear mixed‐effect models to evaluate the utility of phylogenetic diversity in predicting the prevalence of a tick‐borne pathogen. We found that phylogenetic diversity metrics improved our disease prediction models. Predictions of the overall density and infection prevalence of ticks were improved by the addition of phylogenetic metrics, whereas the density of infected nymphs was solely predicted by a phylogenetic metric over traditional species diversity or richness. Our study found that phylogenetic diversity improves statistical predictions of the Lyme disease pathogen and entomological risk in the western United States and may be informative in other contexts and systems as well.
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- Award ID(s):
- 1750037
- PAR ID:
- 10668856
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Ecosphere
- Volume:
- 16
- Issue:
- 7
- ISSN:
- 2150-8925
- Page Range / eLocation ID:
- 70338
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/ecs2.70338
