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Abstract Pathogens utilize different modes of transmission to maximize transmission success. In vector‐borne disease systems, both vertical and horizontal modes of transmission are common, but the relative contribution of these modes is not well understood but may be determined by host genetics, physiology, or environmental conditions. This study focuses on an emerging tick‐borne relapsing fever pathogen,Borrelia miyamotoi, that can be transmitted both vertically and horizontally. The enzootic cycle of this pathogen has not been described in the western USA where it was recently found in the tick species,Ixodes pacificus. Our field surveys found that all three life stages ofI. pacificuscarry the pathogen, and therefore, all stages pose some level of disease risk to humans. The prevalence of infection increases with each life stage suggesting that horizontal transmission is important in the persistence of this pathogen in the enzootic cycle. In support of this finding, we found that small mammal hosts that are frequently parasitized by juvenile stages ofI. pacificuswere infected withB. miyamotoiand may therefore function as a source of horizontal transmission and enzootic maintenance of this disease. Our data show that in the western USAB. miyamotoiis maintained in natural populations by both transovarial transmission and transmission from blood meal hosts and that synchronous phenology of juvenile stages ofI. pacificusmay facilitate the transmission dynamics ofB. miyamotoiand other vertically transmitted, vector‐borne pathogens.
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Drivers and patterns of microbial community assembly in a Lyme disease vector
Abstract Vector‐borne diseases constitute a major global health burden and are increasing in geographic range and prevalence. Mounting evidence has demonstrated that the vector microbiome can impact pathogen dynamics, making the microbiome a focal point in vector‐borne disease ecology. However, efforts to generalize preliminary findings across studies and systems and translate these findings into disease control strategies are hindered by a lack of fundamental understanding of the processes shaping the vector microbiome and the interactions therein. Here, we use 16S rRNA sequencing and apply a community ecology framework to analyze microbiome community assembly and interactions inIxodes pacificus, the Lyme disease vector in the western United States. We find that vertical transmission routes drive population‐level patterns inI. pacificusmicrobial diversity and composition, but that microbial function and overall abundance do not vary over time or between clutches. Further, we find that theI. pacificusmicrobiome is not strongly structured based on competition but assembles nonrandomly, potentially due to vector‐specific filtering processes which largely eliminate all but the dominant endosymbiont,Rickettsia. At the scale of the individualI. pacificus, we find support for a highly limited internal microbial community, and hypothesize that the tick endosymbiont may be the most important component of the vector microbiome in influencing pathogen dynamics.
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- Award ID(s):
- 1745411
- PAR ID:
- 10460345
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 9
- Issue:
- 13
- ISSN:
- 2045-7758
- Format(s):
- Medium: X Size: p. 7768-7779
- Size(s):
- p. 7768-7779
- Sponsoring Org:
- National Science Foundation
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