Mineral licks: motivational factors for visitation and accompanying disease risk at communal use sites of elk and deer.

Free-ranging cervids acquire most of their essential minerals through forage consumption, though occasionally seek other sources to account for seasonal mineral deficiencies. Mineral sources occur as natural geological deposits (i.e., licks) or as anthropogenic mineral supplements. In both scenarios, these sources commonly serve as focal sites for visitation. We monitored 11 licks in Rocky Mountain National Park, north-central Colorado, using trail cameras to quantify daily visitation indices (DVI) and soil consumption indices (SCI) for Rocky Mountain elk (Cervus elaphus) and mule deer (Odocoileus hemionus) during summer 2006 and documented elk, mule deer, and moose (Alces alces) visiting licks. Additionally, soil samples were collected, and mineral concentrations were compared to discern levels that explain rates of visitation. Relationships between response variables; DVI and SCI, and explanatory variables; elevation class, moisture class, period of study, and concentrations of minerals were examined. We found that DVI and SCI were greatest at two wet, low-elevation licks exhibiting relatively high concentrations of manganese and sodium. Because cervids are known to seek Na from soils, we suggest our observed association of Mn with DVI and SCI was a likely consequence of deer and elk seeking supplemental dietary Na. Additionally, highly utilized licks such as these provide an area of concentrated cervid occupation and interaction, thus increasing risk for environmental transmission of infectious pathogens such as chronic wasting disease, which has been shown to be shed in the saliva, urine, and feces of infected cervids.

Elk use of wallows and potential chronic wasting disease transmission.

Deposition of prions into the environment by infected animals may contribute to transmission and spread of chronic wasting disease (CWD) among free-ranging cervids, and identification of such environmental sources may provide an avenue for managing CWD. We evaluated the role that wallow use by elk (Cervus elaphus) may play in CWD transmission by monitoring wallows with animal-activated cameras throughout their period of use. We monitored 39 wallows from 5 August 2005 to 14 October 2005. Elk visited 20 sites; we recorded 22 events when only male elk wallowed and 374 additional events when male and female elk had naso-oral contact with wallow contents. Because wallows are foci of male elk activity, behaviors at wallows could potentially contribute to the maintenance and transmission of CWD. Our findings, however, suggest that because wallows are only used an average of one or two times a season they may not be important in CWD transmission. The data also suggest that mineral licks could be more important in CWD transmission because they were used more frequently and by three species that contract CWD.

Use of a subepithelial connective tissue graft to treat an area pigmented with graphite.

BACKGROUND: Pigmentations of the oral cavity are commonly noted in clinical practice and may have physiologic, non-physiologic, or pathologic etiologies. The most common non-physiologic localized pigmentation is the amalgam tattoo; another, less common, non-physiologic pigmentation is the graphite tattoo. Graphite tattoos may easily be confused with amalgam tattoos but have only infrequently been reported in the literature. METHODS: This case report discusses a patient with a localized pigmented lesion involving the free gingiva, attached gingiva, and alveolar mucosa. The patient was referred for esthetic enhancement of the area in question. Dental history revealed trauma to the area involving falling on a pencil as a child. The lesion was excised and submitted for histologic examination; a subepithelial connective tissue graft was harvested and utilized to prevent an esthetic defect. RESULTS: Histologic evaluation confirmed graphite within the soft tissue as the etiology of the discoloration. At the 2-month postoperative appointment, a highly esthetic outcome was obtained utilizing a connective tissue graft. CONCLUSIONS: Although less common than the amalgam tattoo, the graphite tattoo may be encountered in the course of routine dental examinations and should be included in a differential diagnosis of any localized pigmented lesion. Although histologic evaluation is necessary to rule out pathology, if the dental history is consistent with the clinical impression of a nonpathologic lesion, such as the graphite tattoo in this case report, treatment with an autogenous connective tissue graft at the time of excision can produce a highly esthetic result and avoid additional surgical procedures in the future.

Procedures for identifying infectious prions after passage through the digestive system of an avian species.

Infectious prion (PrP(Res)) material is likely the cause of fatal, neurodegenerative transmissible spongiform encephalopathy (TSE) diseases(1). Transmission of TSE diseases, such as chronic wasting disease (CWD), is presumed to be from animal to animal(2,3) as well as from environmental sources(4-6). Scavengers and carnivores have potential to translocate PrP(Res) material through consumption and excretion of CWD-contaminated carrion. Recent work has documented passage of PrP(Res) material through the digestive system of American crows (Corvus brachyrhynchos), a common North American scavenger(7). We describe procedures used to document passage of PrP(Res) material through American crows. Crows were gavaged with RML-strain mouse-adapted scrapie and their feces were collected 4 hr post gavage. Crow feces were then pooled and injected intraperitoneally into C57BL/6 mice. Mice were monitored daily until they expressed clinical signs of mouse scrapie and were thereafter euthanized. Asymptomatic mice were monitored until 365 days post inoculation. Western blot analysis was conducted to confirm disease status. Results revealed that prions remain infectious after traveling through the digestive system of crows and are present in the feces, causing disease in test mice.

Could avian scavengers translocate infectious prions to disease-free areas initiating new foci of chronic wasting disease?

Mechanisms for the spread of transmissible spongiform encephalopathy diseases, including chronic wasting disease (CWD) in North American cervids, are incompletely understood, but primary routes include horizontal and environmental transmission. Birds have been identified as potential vectors for a number of diseases, where they ingest or are exposed to infected material and later shed the disease agent in new areas after flying substantial distances. We recently identified American crows (Corvus brachyrhynchos) as having the potential to translocate infectious prions in their feces. Our results suggest that this common, migratory North American scavenger is capable of translocating infectious prions to disease-free areas, potentially seeding CWD infection where no other initial source of pathogen establishment is forthcoming. Here we speculate on the role avian scavengers, like American crows, might play in the spatial dissemination of CWD. We also consider the role mammalian scavengers may play in dispersing prions.

Prion remains infectious after passage through digestive system of American crows (Corvus brachyrhynchos).

Avian scavengers, such as American crows (Corvus brachyrhynchos), have potential to translocate infectious agents (prions) of transmissible spongiform encephalopathy (TSE) diseases including chronic wasting disease, scrapie, and bovine spongiform encephalopathy. We inoculated mice with fecal extracts obtained from 20 American crows that were force-fed material infected with RML-strain scrapie prions. These mice all evinced severe neurological dysfunction 196-231 d postinoculation (x =198; 95% CI: 210-216) and tested positive for prion disease. Our results suggest a large proportion of crows that consume prion-positive tissue are capable of passing infectious prions in their feces (ˆp=1.0; 95% CI: 0.8-1.0). Therefore, this common, migratory North American scavenger could play a role in the geographic spread of TSE diseases.

Increased risk of chronic wasting disease in Rocky Mountain elk associated with decreased magnesium and increased manganese in brain tissue.

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of Rocky Mountain elk in North America. Recent studies suggest that tissue and blood mineral levels may be valuable in assessing TSE infection in sheep and cattle. The objectives of this study were to examine baseline levels of copper, manganese, magnesium, zinc, selenium, and molybdenum in the brains of Rocky Mountain elk with differing prion genotypes and to assess the association of mineral levels with CWD infection. Elk with leucine at prion position 132 had significantly lower magnesium levels than elk with 2 copies of methionine. Chronic wasting disease-positive elk had significantly lower magnesium than control elk. The incorporation of manganese levels in addition to magnesium significantly refined explanatory ability, even though manganese alone was not significantly associated with CWD. This study demonstrated that mineral analysis may provide an additional disease correlate for assessing CWD risk, particularly in conjunction with genotype.