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We evaluated the invasion of plague bacteria Yersinia pestis into a population of black-tailed prairie dogs (Cynomys ludovicianus ; BTPDs) in South Dakota. We aimed to ascertain if Y. pestis invaded slowly or rapidly, and to determine if vector (flea) control or vaccination of BTPDs assisted in increasing survival rates. We sampled BTPDs in 2007 (before Y. pestis documentation), 2008 (year of confirmed invasion), and 2009 (after invasion). We estimated annual BTPD re-encounter rates on three 9-ha plots treated annually with deltamethrin dust for flea control and three 9-ha plots lacking dust. In 2007 and 2008, approximately half the adult BTPDs live-trapped were injected subcutaneously with either an experimental plague vaccine (F1–V fusion protein) or placebo formulation; the remaining individuals were not inoculated. From 2007 to 2009, we sampled 1559 BTPDs on 2542 occasions. During 2007–2008, the prevalence and intensity of fleas on BTPDs were 69–97% lower on the dusted vs. no dust plots. From 2007 to 2008, the annual re-encounter rate of non-inoculated BTPDs was 150% higher on the dusted vs. no dust plots. During the same interval on the dusted plots, the re-encounter rate was 55% higher for vaccinated adult female BTPDs vs. nonvaccinated adult females, but the annual re-encounter rate was 19% lower for vaccinated adult males. By late August 2008, BTPDs were nearly extirpated from the no dust plots. During 2007–2008 and 2008–2009 on the dusted plots, which persisted, the BTPD re-encounter rate was 41% higher for vaccinated vs. non-vaccinated adult females but 35% lower for vaccinated adult males. Yersinia pestis erupted with vigor as it invaded. Flea control enhanced BTPD survival but did not offer full protection. Flea control and F1–V vaccination seemed to have additive, positive effects on adult females. Annual re-encounter rates were reduced for vaccinated adult males; additional experimentation is needed to further evaluate this trend. [Display omitted] • Plague erupted with vigor when invading new habitat. • Flea control greatly enhanced prairie dog survival. • Vaccination influenced adult females and males differently. • Additional experimentation is needed to further evaluate the vaccine trends. [ABSTRACT FROM AUTHOR]

The variable response of wild mice to Yersinia pestis infection, the causative agent of plague, has generated much speculation concerning their role in the ecology of this potentially lethal disease. Researchers have questioned the means by which Y. pestis is maintained in nature and also sought methods for managing the disease. Here we assessed the efficacy of a new tool, the sylvatic plague vaccine (SPV), in wild-caught northern grasshopper mice (Onychomys leucogaster) and commercially acquired Sonoran deer mice (Peromyscus maniculatus sonoriensis). More than 40% of the animals survived a subcutaneous Y. pestis challenge of 175,000 colony forming units (over 30,000 times the white mouse 50% lethal dose) in both vaccine-treated and control groups. Our results indicate that SPV distribution is unlikely to protect adult mice from plague infection in field settings and corroborate the heterogeneous response to Y. pestis infection in mice reported by others. [ABSTRACT FROM AUTHOR]

As part of the national recovery effort, endangered black-footed ferrets (Mustela nigripes) were reintroduced to the Cheyenne River Sioux Reservation in South Dakota, US in 2000. Despite an encouraging start, numbers of ferrets at the site have declined. In an effort to determine possible causes of the population decline, we undertook a pathogen survey in 2012 to detect exposure to West Nile virus (WNV), canine distemper virus (CDV), plague (Yersinia pestis), tularemia (Francisella tularensis), and heartworm (Dirofilaria immitis) using coyotes (Canis latrans) as a sentinel animal. The highest seroprevalence was for WNV with 71% (20/28) of coyotes testing antibody-positive. Seroprevalence of CDV and plague were lower, 27% and 13%, respectively. No evidence of active infection with tularemia or heartworm was seen in the coyotes sampled. As this study did not sample black-footed ferrets themselves, the definitive cause for the decline of this population cannot be determined. However, the presence of coyotes seropositive for two diseases, plague and CDV, lethal to black-footed ferrets, indicated the potential for exposure and infection. The high seroprevalence of WNV in the coyotes indicated a wide exposure to the virus; therefore, exposure of black-footed ferrets to the virus is also likely. Due to the ability of WNV to cause fatal disease in other species, studies may be useful to elucidate the impact that WNV could have on the success of reintroduced black-footed ferrets as well as factors influencing the spread and incidence of the disease in a prairie ecosystem. [ABSTRACT FROM AUTHOR]

Sylvatic plague, caused by the bacterium Yersinia pestis and transmitted by fleas, occurs in prairie dogs of the western United States. Outbreaks can devastate prairie dog communities, often causing nearly 100% mortality. Three competent flea vectors, prairie dog specialists Oropsylla hirsuta and O. tuberculata, and generalist Pulex simulans, are found on prairie dogs and in their burrows. Fleas are affected by climate, which varies across the range of black‐tailed prairie dogs (Cynomys ludovicianus), but these effects may be ameliorated somewhat due to the burrowing habits of prairie dogs. Our goal was to assess how temperature and precipitation affect off‐host flea abundance and whether relative flea abundance varied across the range of black‐tailed prairie dogs. Flea abundance was measured by swabbing 300 prairie dog burrows at six widely distributed sites in early and late summer of 2016 and 2017. Relative abundance of flea species varied among sites and sampling sessions. Flea abundance and prevalence increased with monthly mean high temperature and declined with higher winter precipitation. Predicted climate change in North America will likely influence flea abundance and distribution, thereby impacting plague dynamics in prairie dog colonies. [ABSTRACT FROM AUTHOR]

Plague is a bacterial zoonosis of mammalian hosts and flea vectors. The disease is capable of ravaging rodent populations and transforming ecosystems. Because plague mortality is likely to be predicted by flea parasitism, it is critical to understand vector dynamics. It has been hypothesized that paltry precipitation and reduced vegetative production predispose herbivorous rodents to malnourishment and flea parasitism, and flea parasitism varies directly with plague mortality. We evaluated these hypotheses on five colonies of Utah prairie dogs (UPDs; Cynomys parvidens), on the Awapa Plateau, Utah, US, in 2013–16. Ten flea species were identified among 3,257 fleas from UPDs. These 10 flea species parasitize prairie dogs, mice, rats, voles, ground squirrels, chipmunks, and marmots, all known hosts of plague. The abundance of fleas on individual UPDs (1,198 observations) varied inversely with UPD body condition; fleas were most abundant on lightweight, malnourished UPDs. Flea abundance on UPDs was highest in dry years that were preceded by wet years. Increased precipitation and soil moisture in the prior year might generate humid microclimates in UPD burrows (that could facilitate flea survival and reproduction) and paltry precipitation in the current year could predispose UPDs to malnourishment and flea parasitism. Annual re-encounter rates for UPDs (1,072 observations) were reduced in wetter years preceded by drier years; reduced precipitation and vegetative production might kill UPDs, and increased flea densities in drier years could provide conditions for plague transmission (and UPD mortality) when moisture returns. Re-encounter rates were reduced for UPDs carrying at least one flea compared to UPDs with no detected fleas. These results support the hypothesis that reduced precipitation in the current year predisposes UPDs to flea parasitism. Our results also suggest a link between flea parasitism and UPD mortality. Given documented connections between flea parasitism and plague transmission, our results point toward an effect of flea parasitism on plague-related deaths for individual UPDs, a phenomenon rarely investigated in nature. [ABSTRACT FROM AUTHOR]

An outbreak of rabies occurred in a captive colony of wild-caught big brown bats (Eptesicus fuscus). Five of 27 bats exhibited signs of rabies virus infection 22–51 d after capture or 18–22 d after contact with the index case. Rabid bats showed weight loss, aggression, increased vocalization, hypersalivation, and refusal of food. Antigenic typing and virus sequencing confirmed that all five bats were infected with an identical rabies virus variant that circulates in E. fuscus in the US. Two bats with no signs of rabies virus infection were seropositive for rabies virus-neutralizing antibodies; the brains of these bats had no detectable viral proteins by the direct fluorescence antibody test. We suspect bat-to-bat transmission of rabies virus occurred among our bats because all rabies-infected bats were confined to the cage housing the index case and were infected with viruses having identical sequences of the entire rabies nucleoprotein gene. This outbreak illustrates the risk of rabies virus infection in captive bats and highlights the need for researchers using bats to assume that all wild bats could be infected with rabies virus. [ABSTRACT FROM AUTHOR]

We confirmed safety and immunogenicity of mass-produced vaccine baits carrying an experimental, commercial-source plague vaccine (RCN-F1/V307) expressing Yersinia pestis V and F1 antigens. Forty-five juvenile black-tailed prairie dogs (Cynomys ludovicianus) were randomly divided into three treatment groups (n=15 animals/group). Animals in the first group received one standard-dose vaccine bait (5×107 plaque-forming units [pfu]; STD). The second group received a lower-dose bait (1×107 pfu; LOW). In the third group, five animals received two standard-dose baits and 10 were left untreated but in contact. Two vaccine-treated and one untreated prairie dogs died during the study, but laboratory analyses ruled out vaccine involvement. Overall, 17 of 33 (52%; 95% confidence interval for binomial proportion [bCI] 34−69%) prairie dogs receiving vaccine-laden bait showed a positive anti-V antibody response on at least one sampling occasion after bait consumption, and eight (24%; bCI 11–42%) showed sustained antibody responses. The STD and LOW groups did not differ (P≥0.78) in their proportions of overall or sustained antibody responses after vaccine bait consumption. Serum from one of the nine (11%; bCI 0.3–48%) surviving untreated, in-contact prairie dogs also had detectable antibody on one sampling occasion. We did not observe any adverse effects related to oral vaccination. [ABSTRACT FROM AUTHOR]

The article presents a case study which investigates the effectiveness of the RCN-F1/V307 vaccine in protecting the prairie dog population from plague diseases which includes the raccoon pox virus. Topics discussed include the use of treated baits, wildlife observation and collection techniques in the study, the use of the statistical package R (version 2.15.2) in the analysis of the acquired data, and a detailed analysis of the results.

The article provides information on a study which tracked the replication of monkeypox (MPX) virus infection in black-tailed prairie dogs using bioluminescent imaging (BLI) and compared observations with polymerase chain reaction (PCR) results and virus isolation from tissues collected postmortem. Topics covered include the prevalence of MPX in Central and West Africa and the African rodents which reportedly brought MPX virus from Ghana to the U.S. via the exotic pet trade.

The article presents the results of the test of a complete lateral flow device developed for the detection of specific antibodies to Yersinia pestis F1 and V antigens as a surveillance for sylvatic plague exposure in wild animals. It mentions the detection of anti-F1 and anti-V antibodies in samples from three wild animals, and the comparison of the results with the results of hemagglutination (HA) test and enzyme-linked immunosorbent assay (ELISA).

The article presents the evaluation of bait distribution strategies for the delivery of an oral vaccine to prairie dogs or Cynomys species against the zoonotic disease plague. It talks about the use of biomarker and rhodamine B. The results of distributing baits around active burrows or along transects at different densities are presented. Also included are the findings of the bait uptake by the four species of prairie dogs and other species of small mammals.

The article discusses study that examined potential mechanisms accounting for survival of a colony Gunnison's prairie dogs in the Aubrey Valley (AV) of northern Arizona. Prairie dogs are highly susceptible to Yersinia pestis, but a colony in AV was able to survive several regional epizootics of plague. The immune responses of the Gunnison's prairie dog to Y. pestis is investigated. The importance of innate immunity is highlighted.

The article discusses the results of a study on the factors affecting the survival of the population of the Gunnison's prairie dogs in Arizona. The authors analyzed the genetic expression at 58 immune proteins of dogs utilizing a multiplexed enzyme-linked immunosorbent assay. They discovered a subset of proteins that are important in coagulation and inflammation and T-cell responses in prairie dogs in Aubrey Valley than in Seligman, Arizona.

The article discusses the results of a study on the effectiveness of recombinant F1-V fusion protein vaccine in the prevention of infection caused by Yersinia pestis bacteria in Canada lynx. It found no evidence of injection or systemic reactions to the vaccine. It mentions that the vaccine is likely to stimulate antibody responses that may help protect Canada lynx from infection. It adds that no apparent differences in survival between vaccinated and unvaccinated Canada lynx.

The article presents research on oral vaccination against Yersinia pestis in prairie dogs or Cynomys species. It references a study by Julia Rodriguez-Ramos Fernandez and Tonie E. Rocke published in the same issue of the journal. It examines the use of rhodamine B (RB) as a biomarker to determine the efficacy of oral plague vaccination for animals that consume vaccine baits.