SURVEILLANCE FOR AN EMERGENT HOOF DISEASE IN ELK (CERVUS ELAPHUS) IN THE US PACIFIC WEST SUPPLEMENTED BY 16S RRNA GENE AMPLICON SEQUENCING.

A novel hoof disease of elk (Cervus elaphus) was described in southwestern Washington, US, in 2008 and was subsequently diagnosed in an adjacent area in northwestern Oregon in 2014. The disease, currently referred to as treponeme-associated hoof disease (TAHD), is characterized by lesions ranging from mild erosions, to severe ulcers with underrunning of the hoof capsule and heel-sole junction, to overgrown and avulsed hoof capsules. Histologically, lesions exhibit epithelial erosion or ulceration, suppurative inflammation, and the presence of argyrophilic spirochetes. We used data collected by the Washington Department of Fish and Wildlife and Oregon Department of Fish and Wildlife from 2008 to 2017 as reference for disease distribution. We then conducted enhanced surveillance in 2018-20 by obtaining 164 submissions from four US Pacific West states. We detected TAHD for the first time in Idaho and northern California, as well as in multiple counties in Washington and Oregon where it had not been previously reported. Given the unexpectedly broad disease distribution, continued surveillance is warranted to determine the full geographic extent of TAHD. From samples of 22 elk, we investigated 16S rRNA gene amplicon sequencing as a technique that could be used to supplement TAHD surveillance. Operational taxonomic units of the family Spirochaetaceae were identified in 10 of 12 histologically diagnosed TAHD-positive cases and two of 10 TAHD-negative cases. Phyla Spirochaetae (P<0.008), Fusobacteria (P<0.006), and Tenericutes (P<0.01) were overrepresented in samples from TAHD-positive feet when compared with TAHD-negative elk. A unique spirochete, PT19, was detected in hooves of 11 elk and from at least one elk in each state. Results support the use of 16S rRNA gene amplicon sequencing as a reliable and informative tool to supplement investigations into distribution and etiology of this presumed polybacterial disease.

Pathogen surveillance and epidemiology in endangered Peninsular bighorn sheep (Ovis canadensis nelsoni).

Peninsular bighorn sheep (Ovis canadensis nelsoni) are found exclusively in Southern California and Baja Mexico. They are federally endangered due to multiple threats, including introduced infectious disease. From 1981 - 2017, we conducted surveillance for 16 pathogens and estimated population sizes, adult survival, and lamb survival. We used mixed effects regression models to assess disease patterns at the individual and population levels. Pathogen infection/exposure prevalence varied both spatially and temporally. Our findings indicate that the primary predictor of individual pathogen infection/exposure was the region in which an animal was captured, implying that transmission is driven by local ecological or behavioral factors. Higher Mycoplasma ovipneumoniae seropositivity was associated with lower lamb survival, consistent with lambs having high rates of pneumonia-associated mortality, which may be slowing population recovery. There was no association between M. ovipneumoniae and adult survival. Adult survival was positively associated with population size and parainfluenza-3 virus seroprevalence in the same year, and orf virus seroprevalence in the previous year. Peninsular bighorn sheep are recovering from small population sizes in a habitat of environmental extremes, compounded by infectious disease. Our research can help inform future pathogen surveillance and population monitoring for the long-term conservation of this population.

MORTALITY OF SELECTED AVIAN ORDERS SUBMITTED TO A WILDLIFE DIAGNOSTIC LABORATORY (SOUTHEASTERN COOPERATIVE WILDLIFE DISEASE STUDY, USA): A 36-YEAR RETROSPECTIVE ANALYSIS.

To determine the relative importance of mortality factors for birds and to assess for patterns in avian mortality over time, we retrospectively examined data of birds submitted to the Southeastern Cooperative Wildlife Disease Study (SCWDS; http://vet.uga.edu/scwds ), US, from 1976 to 2012. During this period, SCWDS, a wildlife diagnostic laboratory, received 2,583 wild bird specimens, from the taxonomic orders Apodiformes, Caprimulgiformes, Cuculiformes, Passeriformes, and Piciformes, originating from 22 states. Data from 2,001 of these birds were analyzed using log-linear models to explore correlations between causes of mortality, taxonomic family, demography, geographic location, and seasonality. Toxicosis was the major cause of mortality, followed by trauma, bacterial infection, physiologic stress, viral infection, and other (mortality causes with low sample numbers and etiologies inconsistent with established categories). Birds submitted during fall and winter had a higher frequency of parasitic infections, trauma, and toxicoses, whereas birds submitted during the spring and summer were more likely to die of an infectious disease, physiologic stress, or trauma. We noted a decrease in toxicoses concurrent with an increase in bacterial infections and trauma diagnoses after the mid-1990s. Toxicosis was the most commonly diagnosed cause of death among adult birds; the majority of juveniles died from physiologic stress, trauma, or viral infections. Infectious agents were diagnosed more often within the families Cardinalidae and Fringilidae, whereas noninfectious etiologies were the primary diagnoses in the Bombycillidae, Parulidae, Sturnidae, Turdidae, and Icteridae. There are important inherent limitations in the examination of data from diagnostic labs, as submission of cases varies in timing, frequency, location, and species and is often influenced by several factors, including media coverage of high-profile mortality events. Notwithstanding, our data provide a rare opportunity to examine long-term, regional, and temporal patterns in causes of avian mortality, and they allow for the analysis of novel and rare mortality factors.

Cyclic avian mass mortality in the northeastern United States is associated with a novel orthomyxovirus.

UNLABELLED: Since 1998, cyclic mortality events in common eiders (Somateria mollissima), numbering in the hundreds to thousands of dead birds, have been documented along the coast of Cape Cod, MA, USA. Although longitudinal disease investigations have uncovered potential contributing factors responsible for these outbreaks, detecting a primary etiological agent has proven enigmatic. Here, we identify a novel orthomyxovirus, tentatively named Wellfleet Bay virus (WFBV), as a potential causative agent of these outbreaks. Genomic analysis of WFBV revealed that it is most closely related to members of the Quaranjavirus genus within the family Orthomyxoviridae. Similar to other members of the genus, WFBV contains an alphabaculovirus gp64-like glycoprotein that was demonstrated to have fusion activity; this also tentatively suggests that ticks (and/or insects) may vector the virus in nature. However, in addition to the six RNA segments encoding the prototypical structural proteins identified in other quaranjaviruses, a previously unknown RNA segment (segment 7) encoding a novel protein designated VP7 was discovered in WFBV. Although WFBV shows low to moderate levels of sequence similarity to Quaranfil virus and Johnston Atoll virus, the original members of the Quaranjavirus genus, additional antigenic and genetic analyses demonstrated that it is closely related to the recently identified Cygnet River virus (CyRV) from South Australia, suggesting that WFBV and CyRV may be geographic variants of the same virus. Although the identification of WFBV in part may resolve the enigma of these mass mortality events, the details of the ecology and epidemiology of the virus remain to be determined. IMPORTANCE: The emergence or reemergence of viral pathogens resulting in large-scale outbreaks of disease in humans and/or animals is one of the most important challenges facing biomedicine. For example, understanding how orthomyxoviruses such as novel influenza A virus reassortants and/or mutants emerge to cause epidemic or pandemic disease is at the forefront of current global health concerns. Here, we describe the emergence of a novel orthomyxovirus, Wellfleet Bay virus (WFBV), which has been associated with cyclic large-scale bird die-offs in the northeastern United States. This initial characterization study provides a foundation for further research into the evolution, epidemiology, and ecology of newly emerging orthomyxoviruses, such as WFBV, and their potential impacts on animal and/or human health.

Avian oncogenesis induced by lymphoproliferative disease virus: a neglected or emerging retroviral pathogen?

Lymphoproliferative disease virus (LPDV) is an exogenous oncogenic retrovirus that induces lymphoid tumors in some galliform species of birds. Historically, outbreaks of LPDV have been reported from Europe and Israel. Although the virus has previously never been detected in North America, herein we describe the widespread distribution, genetic diversity, pathogenesis, and evolution of LPDV in the United States. Characterization of the provirus genome of the index LPDV case from North America demonstrated an 88% nucleotide identity to the Israeli prototype strain. Although phylogenetic analysis indicated that the majority of viruses fell into a single North American lineage, a small subset of viruses from South Carolina were most closely related to the Israeli prototype. These results suggest that LPDV was transferred between continents to initiate outbreaks of disease. However, the direction (New World to Old World or vice versa), mechanism, and time frame of the transcontinental spread currently remain unknown.

Mediastinal teratoma in a free-ranging American black bear (Ursus americanus).

A 2.75-yr-old female American black bear (Ursus americanus) was found emaciated and unable to rise. It was euthanized due to the perceived poor prognosis. An approximately 18 x 8 x 10-cm, multiloculated, well-demarcated mass that extended from the bifurcation of the trachea, laterally displacing the lung lobes and caudally displacing the heart. The mass contained fibrous connective tissue, cartilage, bone, nervous tissue, smooth muscle, and a variety of epithelial structures. A mediastinal teratoma was diagnosed based on the microscopic features of the neoplasm.

Infestation of two brown-headed cowbirds (Molothrus ater) with the hunchback mite (Harpirhynchus quasimodo).

A recently described North American mite, Harpirhynchus quasimodo (Acariformes: Harpirhynchidae), was identified in a wild brown-headed cowbird (Molothrus ater) from Tennessee and another from Arkansas, U. S. A., during 2010 and 2011, respectively. Consistent with a single previous report of H. quasimodo infestation, both cowbirds had multiple skin masses composed of epidermal cysts filled with harpirhynchid mites, keratin, and cellular debris. Although very little is currently known about this avian mite, these three reports suggest that H. quasimodo infestation is a rare source of overt disease in free-ranging brown-headed cowbirds from the southeastern United States; however, further research and surveillance efforts are needed.