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A Novel Retrovirus (Gunnison’s Prairie Dog Retrovirus) Associated With Thymic Lymphoma in Gunnison’s Prairie Dogs in Colorado, USA

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Abstract

As part of research and wildlife disease surveillance efforts, we performed necropsy examinations of 125 free-ranging (n = 114) and captive (n = 11) prairie dogs in Colorado from 2009 to 2017. From these cases, we identified three cases of thymic lymphoma in free-ranging Gunnison’s prairie dogs (Cynomys gunnisoni), and we identified a novel retroviral sequence associated with these tumors. The viral sequence is 7700 nucleotides in length and exhibits a genetic organization that is consistent with the characteristics of a type D betaretrovirus. The proposed name of this virus is Gunnison’s prairie dog retrovirus (GPDRV). We screened all 125 prairie dogs for the presence of GPDRV using PCR with envelope-specific primers and DNA extracted from spleen samples. Samples were from Gunnison’s prairie dogs (n = 59), black-tailed prairie dogs (Cynomys ludovicianus) (n = 40), and white-tailed prairie dogs (Cynomys leucurus) (n = 26). We identified GPDRV in a total of 7/125 (5.6%) samples including all three of the prairie dogs with thymic lymphoma, as well as spleen from an additional four Gunnison’s prairie dogs with no tumors recognized at necropsy. None of the GPDRV-negative Gunnison’s prairie dogs had thymic lymphomas. We also identified a related, apparently endogenous retroviral sequence in all prairie dog samples. These results suggest that GPDRV infection may lead to development of thymic lymphoma in Gunnison’s prairie dogs.

Molly D Butler  1 , Karen Griffin  2 , Connie D Brewster  1 , Marylee L Kapuscinski  1 , Mark D Stenglein  1 , Daniel W Tripp  2 , Sandra L Quackenbush  1 , Karen A Fox  2
Affiliations

 

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Rabbit Hemorrhagic Disease Virus 2 Confirmed in Wild Rabbits in the United States

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Rabbit hemorrhagic disease virus 2 (RHDV2), a notifiable foreign animal disease, has been confirmed for

the first time in wild rabbits in the United States.

Read more:  Rabbit

If you live in New Mexico….and in the event you find a sick or dead rabbit…

From Wildlife Rescue: “The disease has been found in Southern and Eastern NM and it is only a matter or time when it will be found here in our area. It is highly contagious, but only to other rabbits, domestic rabbits and species within the rabbit family. Baby rabbits don’t seem to be affected at least at this time.”

If we (Wildlife Rescue) receive any phone calls regarding someone reporting dead or sick wild rabbits, we are asking them for info on where these rabbits are located and reporting this to USGS/NMG&F or to our mammal coordinator. We are telling people not to handle or rescue these rabbits themselves or to wear gloves if handling them.

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FLEA PARASITISM AND HOST SURVIVAL IN A PLAGUE-RELEVANT SYSTEM: THEORETICAL AND CONSERVATION IMPLICATIONS.

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Author information:
1. US Geological Survey, Fort Collins Science Center, 2150 Centre Avenue, Building C, Fort Collins, CO 80526, USA’.
2. US Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, WI 53711, USA

Abstract

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, USA, 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.

 

PMID: 31880988
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