Possible Vector Dissemination by Swift Foxes following a Plague Epizootic in Black-tailed Prairie Dogs in Northwestern Texas

Abstract

To determine whether swift foxes (Vulpes velox) could facilitate transmission of Yersinia pestis to uninfected black-tailed prairie dog (Cynomys ludovicianus) colonies by acquiring infected fleas, ectoparasite and serologic samples were collected from swift foxes living adjacent to prairie dog towns during a 2004 plague epizootic in northwestern Texas, USA. A previous study (1999-2001) indicated that these swift foxes were infested almost exclusively with the flea Pulex irritans. Black-tailed prairie dogs examined from the study area harbored only Pulex simulans and Oropsylla hirsuta. Although P. irritans was most common, P. simulans and O. hirsuta were collected from six swift foxes and a single coyote (Canis latrans) following the plague epizootic. Thus, both of these canids could act as transport hosts (at least temporarily) of prairie dog fleas following the loss of their normal hosts during a plague die-off. All six adult swift foxes tested positive for antibodies to Y. pestis. All 107 fleas from swift foxes tested negative for Y. pestis by mouse inoculation. Although swift foxes could potentially carry Y. pestis to un-infected prairie dog colonies, we believe they play only a minor role in plague epidemiology, considering that they harbored just a few uninfected prairie dog fleas (P. simulans and O. hirsuta).

Ecological Traits Driving the Outbreaks and Emergence of Zoonotic Pathogens

“…, O. tuberculata cynomuris, and Pulex simulans. Except for P. simulans, which is also found on carnivores, the fleas associated with prairie dogs are rarely found on other mammals (Brinkerhoff et al 2006, McGee et al 2006, Salkeld et al 2007).…”

“…pestis-positive fleas have yet to be found on carnivores (McGee et al 2006, Salkeld and Stapp 2006, Salkeld et al 2007). It is worth noting that prairie dog-and carnivore-mediated dispersal of Y. pestis are not mutually exclusive, and the importance of carnivores in the spread of plague will likely vary, depending on the species involved (Brinkerhoff et al 2009).…”

Ectoparasites on Meso-carnivores in the Desert-steppe of Mongolia

“…The Pulex genus comprises six species (Whithing et al, 2008), but only two of them, P. simulans and P. irritans, are reported to infest wild carnivore hosts (Harrison et al, 2003;McGee et al, 2006;Salkeld et al, 2007;Gabrel et al, 2009;Dobler & Pfeff er, 2011). In concordance with our fi ndings, P. irritans usually predominates and is often the most common fl ea on the genus Vulpes, while P. simulans is typically the most common fl ea on gray foxes (Urocyon cinereoargenteus) and coyotes (Canis latrans) (Harrison et al, 2003;McGee et al, 2006;Salkeld et al, 2007;Gabrel et al, 2009;Dobler & Pfeff er, 2011). As might be expected, we found that P. irritans had a broader host distribution than other species.…”

“…Also, researchers have identifi ed wild canids as carriers of Yersinia pestis (the causal agent of plague) among prairie dog (Cynomys spp.) colonies (McGee et al, 2006). Many fl ea species that function as important vectors of fl ea-borne diseases (e.g., Pulex spp., Oropsylla spp., and Ctenocephalides spp.)…”

“…Many fl ea species that function as important vectors of fl ea-borne diseases (e.g., Pulex spp., Oropsylla spp., and Ctenocephalides spp.) have been recorded from mammalian carnivores, such as wild felids, canids, and mustelids (McGee et al, 2006;Marquez et al, 2009;Lopez-Perez et al, 2017) Knowledge on the spectrum of parasites carried by host species and determination of their ectoparasite infestation levels is essential for understanding the dynamics of relevant diseases and establishing control policies. Nevertheless, in the case of meso-carnivores, very few studies provide quantitative data on the level of infestation of external parasites, both in terms of prevalence and abundance.…”