The Role of Short-lived Rodents and Their Fleas in Plague Ecology on Prairie Dog Colonies PDF Download

Author: Gebbiena M. Bron
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Languages : en
Pages : 0

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Book Description
Multi-host and multi-vector diseases are complex. Plague, caused by the bacterium Yersinia pestis, affects many mammalian species and can be transmitted via several routes, but flea-borne transmission is the primary mode of transmission. Plague can decimate prairie dog (Cynomys spp.) colonies and other species that depend on them, including the endangered black-footed ferret (Mustela nigripes). After decades of research, plague dynamics on prairie dog colonies are still poorly understood. The purpose of this dissertation was to gain a holistic understanding of the complex dynamics of plague ecology in the western United States, by assessing the role of short-lived rodents and their fleas in plague maintenance and epizootics on prairie dog colonies. Our study was conducted in conjunction with a large-scale, blind, placebo-controlled, field efficacy trial on the newly developed, orally-delivered sylvatic plague vaccine (SPV) for prairie dogs from 2013 to 2015, led by the U.S. Geological Survey, National Wildlife Health Center. Using a combination of field and laboratory-based studies, we observed that consumption of the SPV did not protect deer mice (Peromyscus maniculatus) and Northern grasshopper mice (Onychomys leucogaster) from plague and deer mouse abundance and short-lived rodent community structure (richness and evenness) were not significantly different between placebo and vaccine treated prairie dog colonies. Surprisingly, we detected plague positive mouse fleas (Aetheca wagneri, Pleochaetis exilis, Orchopeas leucopus) on mice prior to plague-induced declines in black-tailed prairie dogs (C. ludovicianus) in Montana and white-tailed prairie dogs (C. leucurus) in Wyoming, but not during plague outbreaks. To determine the possible source of plague infection in the flea pools we used amplicon deep sequencing and we did not detect prairie dog DNA. In addition, rodent-flea interaction networks were highly specialized, geographically different and fleas rarely switched from short-lived rodents to prairie dogs and vice versa. Thus we showed that mice are involved in the plague cycle on prairie dog colonies, but their role remains uncertain and the direct connection between short-lived rodents and prairie dogs stays anecdotal. Overall, these studies demonstrate the complexity involved in plague ecology and highlight the importance of a holistic approach to studying multi-host and multi-vector diseases.