Abstract
Outbreaks of plague, a flea‐vectored bacterial disease, occur periodically in prairie dog populations in the western United States. In order to understand the conditions that are conducive to plague outbreaks and potentially predict spatial and temporal variations in risk, it is important to understand the factors associated with flea abundance and distribution that may lead to plague outbreaks. We collected and identified 20,041 fleas from 6,542 individual prairie dogs of four different species over a 4‐year period along a latitudinal gradient from Texas to Montana. We assessed local climate and other factors associated with flea prevalence and abundance, as well as the incidence of plague outbreaks. Oropsylla hirsuta, a prairie dog specialist flea, and Pulex simulans, a generalist flea species, were the most common fleas found on our pairs. High elevation pairs in Wyoming and Utah had distinct flea communities compared with the rest of the study pairs. The incidence of prairie dogs with Yersinia pestis detections in fleas was low (n = 64 prairie dogs with positive fleas out of 5,024 samples from 4,218 individual prairie dogs). The results of our regression models indicate that many factors are associated with the presence of fleas. In general, flea abundance (number of fleas on hosts) is higher during plague outbreaks, lower when prairie dogs are more abundant, and reaches peak levels when climate and weather variables are at intermediate levels. Changing climate conditions will likely affect aspects of both flea and host communities, including population densities and species composition, which may lead to changes in plague dynamics. Our results support the hypothesis that local conditions, including host, vector, and environmental factors, influence the likelihood of plague outbreaks, and that predicting changes to plague dynamics under climate change scenarios will have to consider both host and vector responses to local factors.
Highlights
Sylvatic plague, caused by the bacteria Yersinia pestis, manifests in the western United States as episodic outbreaks in prairie dogs, squirrels, and small rodents, with occasional spillover to human populations (Gage, 1998)
In order to understand the conditions that are conducive to plague outbreaks and potentially predict spatial and temporal variations in risk, it is important to understand the factors associated with flea abundance, prevalence, and distribution that may lead to plague outbreaks
We evaluated factors associated with prevalence of fleas and overall flea abundance, including variables related to climate and seasonal weather patterns (NDVI [normalized difference vegetation index—a measure of vegetation greenness, see Table 1], number of days with a temperature over 85°F [Collinge et al, 2005], amount of precipitation during the prior year’s growing season, winter precipitation amount, and day of sampling), plot-level variables, and individual covariates (Table 1)
Summary
Sylvatic plague, caused by the bacteria Yersinia pestis, manifests in the western United States as episodic outbreaks in prairie dogs, squirrels, and small rodents, with occasional spillover to human populations (Gage, 1998). A number of studies have indicated that small rodent composition (Stapp et al, 2009) and local weather conditions (Collinge et al, 2005; Hubbart, Jachowski, & Eads, 2011; Savage, Reich, Hartley, Stapp, & Antolin, 2011) may play a role in contributing to plague epizootics, potentially through their effects on flea distribution and abundance. These factors likely vary geographically in the strength of their effects. Elucidating the relationship between flea species composition, abundance and distribution, the occurrence of plague, and environmental factors will provide information to management agencies responsible for controlling plague, as well as help predict how plague dynamics may change under future climate conditions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
