Geology topics
Publications and source records attributed to Robert J. Dusek.
We describe a die-off of little brown bats ( Myotis lucifugus carissima ) associated with acute intoxication with microcystin-LR in 2016 at Scofield Reservoir in Utah. High levels of this cyanotoxin in water from the reservoir and gastrointestinal content of bats supported this diagnosis.
The USGS National Wildlife Health Center (NWHC) Quarterly Mortality Report provides brief summaries of epizootic mortality and morbidity events by quarter. The write-ups, highlighting epizootic events and other wildlife disease topics of interest, are published in the Wildlife Disease Association quarterly newsletter. A link is provided in this WDA newsletter to the Wildlife Health Information Sharing Partnership event reporting system (WHISPers) so readers can view associated data.
No abstract available.
Objective Marijuana ( Cannabis spp.) growing operations (MGO) in California have increased substantially since the mid-1990s. One environmental side-effect of MGOs is the extensive use of anticoagulant rodenticides (AR) to prevent damage to marijuana plants caused by wild rodents. In association with a long-term demographic study, we report on an observation of brodifacoum AR exposure in a threatened species, the northern spotted owl ( Strix occidentalis caurina ), found freshly dead within 669–1347 m of at least seven active MGOs. Results Liver and blood samples from the dead northern spotted owl were tested for 12 rodenticides. Brodifacoum was the only rodenticide detected in the liver (33.3–36.3 ng/g) and blood (0.48–0.54 ng/ml). Based on necropsy results, it was unclear what role brodifacoum had in the death of this bird. However, fatal AR poisoning has been previously reported in owls with relatively low levels of brodifacoum residues in the liver. One likely mechanism of AR transmission from MGOs to northern spotted owls in California is through ingestion of AR contaminated prey that frequent MGOs. The proliferation of MGOs with their use of ARs in forested landscapes used by northern spotted owls may pose an additional stressor for this threatened species.
Highly pathogenic avian influenza virus (HPAIV) is a multihost pathogen with lineages that pose health risks for domestic birds, wild birds, and humans. One mechanism of intercontinental HPAIV spread is through wild bird reservoirs, and wild birds were the likely sources of a Eurasian (EA) lineage HPAIV into North America in 2014. The introduction resulted in several reassortment events with North American (NA) lineage low-pathogenic avian influenza viruses and the reassortant EA/NA H5N2 went on to cause one of the largest HPAIV poultry outbreaks in North America. We evaluated three hypotheses about novel HPAIV introduced into wild and domestic bird hosts: (i) transmission of novel HPAIVs in wild birds was restricted by mechanisms associated with highly pathogenic phenotypes; (ii) the HPAIV poultry outbreak was not self-sustaining and required viral input from wild birds; and (iii) reassortment of the EA H5N8 generated reassortant EA/NA AIVs with a fitness advantage over fully Eurasian lineages in North American wild birds. We used a time-rooted phylodynamic model that explicitly incorporated viral population dynamics with evolutionary dynamics to estimate the basic reproductive number ( R 0 ) and viral migration among host types in domestic and wild birds, as well as between the EA H5N8 and EA/NA H5N2 in wild birds. We did not find evidence to support hypothesis (i) or (ii) as our estimates of the transmission parameters suggested that the HPAIV outbreak met or exceeded the threshold for persistence in wild birds ( R 0 > 1) and poultry ( R 0 ≈ 1) with minimal estimated transmission among host types. There was also no evidence to support hypothesis (iii) because R 0 values were similar among EA H5N8 and EA/NA H5N2 in wild birds. Our results suggest that this novel HPAIV and reassortments did not encounter any transmission barriers sufficient to prevent persistence when introduced to wild or domestic birds.
In 2013, a mortality event of nonnative, feral Rosy-faced Lovebirds ( Agapornis roseicollis ) in residential backyards in Maricopa County, Arizona, US was attributed to infection with Chlamydia psittaci . In June 2014, additional mortality occurred in the same region. Accordingly, in August 2014 we sampled live lovebirds and sympatric bird species visiting backyard bird feeders to determine the prevalence of DNA and the seroprevalence of antibodies to C. psittaci using real-time PCR-based testing and elementary body agglutination, respectively. Chlamydia psittaci DNA was present in conjunctival-choanal or cloacal swabs in 93% (43/46) of lovebirds and 10% (14/142) of sympatric birds. Antibodies to C. psittaci were detected in 76% (31/41) of lovebirds and 7% (7/102) of sympatric birds. Among the sympatric birds, Rock Doves ( Columba livia ) had the highest prevalence of C. psittaci DNA (75%; 6/8) and seroprevalence (25%; 2/8). Psittacine circovirus 1 DNA was also identified, using real-time PCR-based testing, from the same swab samples in 69% (11/16) of species sampled, with a prevalence of 80% (37/46) in lovebirds and 27% (38/142) in sympatric species. The presence of either Rosy-faced Lovebirds or Rock Doves at residential bird feeders may be cause for concern for epizootic and zoonotic transmission of C. psittaci in this region.
No abstract available.
No abstract available.
In November and December of 2013, a large mortality event involving 15,000 - 20,000 eared grebes ( Podiceps nigricollis ) occurred at the Great Salt Lake (GSL), UT. The onset of the outbreak in grebes was followed by a mortality event in > 86 bald eagles ( Haliaeetus leucocephalus ). During the die-off, West Nile virus (WNV) was detected by RT-PCR or viral culture in carcasses of grebes and eagles submitted to the National Wildlife Health Center. However, no mosquito activity, the primary vector of WNV, was detected by the State of Utah's WNV monitoring program. Transmission of WNV has rarely been reported during the winter in North America in the absence of known mosquito activity; however, the size of this die-off, the habitat in which it occurred, and the species involved are unique. We experimentally investigated whether WNV could survive in water with a high saline content, as found at the GSL, and whether brine shrimp, the primary food of migrating eared grebes on the GSL, could have played a role in transmission of WNV to feeding birds. We found that WNV can survive up to 72 h at 4°C in water containing 30 — 150 ppt NaCl and brine shrimp, incubated with WNV in 30 ppt NaCl, may adsorb WNV to their cuticle and, through feeding, may infect epithelial cells of their gut. Both mechanisms may have potentiated the WNV die-off in migrating eared grebes on the GSL.
We evaluated the potential transmission of avian influenza viruses (AIV) in wildlife species in three settings in association with an outbreak at a poultry facility: 1) small birds and small mammals on a poultry facility that was affected with highly pathogenic AIV (HPAIV) in April 2015; 2) small birds and small mammals on a nearby poultry facility that was unaffected by HPAIV; and 3) small birds, small mammals, and waterfowl in a nearby natural area. We live-captured small birds and small mammals and collected samples from hunter-harvested waterfowl to test for active viral shedding and evidence of exposure (serum antibody) to AIV and the H5N2 HPAIV that affected the poultry facility. We detected no evidence of shedding or specific antibody to AIV in small mammals and small birds 5 mo after depopulation of the poultry. We detected viral shedding and exposure to AIV in waterfowl and estimated approximately 15% viral shedding and 60% antibody prevalence. In waterfowl, we did not detect shedding or exposure to the HPAIV that affected the poultry facility. We also conducted camera trapping around poultry carcass depopulation composting barns and found regular visitation by four species of medium-sized mammals. We provide preliminary data suggesting that peridomestic wildlife were not an important factor in the transmission of AIV during the poultry outbreak, nor did small birds and mammals in natural wetland settings show wide evidence of AIV shedding or exposure, despite the opportunity for exposure.
Introduction Through the Science Strategy for Highly Pathogenic Avian Influenza (HPAI) in Wildlife and the Environment, the USGS will assess avian influenza (AI) dynamics in an ecological context to inform decisions made by resource managers and policymakers from the local to national level. Through collection of unbiased scientific information on the ecology of AI viruses and wildlife hosts in a changing world, the U.S. Geological Survey (USGS) will enhance the development of AI forecasting tools and ensure this information is integrated with a quality decision process for managing HPAI. The overall goal of this USGS Science Strategy for HPAI in Wildlife and the Environment goes beyond documenting the occurrence and distribution of AI viruses in wild birds. The USGS aims to understand the epidemiological processes and environmental factors that influence HPAI distribution and describe the mechanisms of transmission between wild birds and poultry. USGS scientists developed a conceptual model describing the process linking HPAI dispersal in wild waterfowl to the outbreaks in poultry. This strategy focuses on five long-term science goals, which include: Science Goal 1—Augment the National HPAI Surveillance Plan; Science Goal 2—Determine mechanisms of HPAI disease spread in wildlife and the environment; Science Goal 3—Characterize HPAI viruses circulating in wildlife; Science Goal 4—Understand implications of avian ecology on HPAI spread; and Science Goal 5—Develop HPAI forecasting and decision-making tools. These goals will help define and describe the processes outlined in the conceptual model with the ultimate goal of facilitating biosecurity and minimizing transfer of diseases across the wildlife-poultry interface. The first four science goals are focused on scientific discovery and the fifth goal is application-based. Decision analyses in the fifth goal will guide prioritization of proposed actions in the first four goals.
A novel highly pathogenic avian influenza virus belonging to the H5 clade 2.3.4.4 variant viruses was detected in North America in late 2014. Motivated by the identification of these viruses in domestic poultry in Canada, an intensive study was initiated to conduct highly pathogenic avian influenza surveillance in wild birds in the Pacific Flyway of the United States. A total of 4,729 hunter-harvested wild birds were sampled and highly pathogenic avian influenza virus was detected in 1.3% (n = 63). Three H5 clade 2.3.4.4 subtypes were isolated from wild birds, H5N2, H5N8, and H5N1, representing the wholly Eurasian lineage H5N8 and two novel reassortant viruses. Testing of 150 additional wild birds during avian morbidity and mortality investigations in Washington yielded 10 (6.7%) additional highly pathogenic avian influenza isolates (H5N8 = 3 and H5N2 = 7). The geographically widespread detection of these viruses in apparently healthy wild waterfowl suggest that the H5 clade 2.3.4.4 variant viruses may behave similarly in this taxonomic group whereby many waterfowl species are susceptible to infection but do not demonstrate obvious clinical disease. Despite these findings in wild waterfowl, mortality has been documented for some wild bird species and losses in US domestic poultry during the first half of 2015 were unprecedented.
In 2014, Clade 2.3.4.4 H5N8 highly pathogenic avian influenza (HPAI) viruses spread across the Republic of Korea and ultimately were reported in China, Japan, Russia and Europe. Mortality associated with a reassortant HPAI H5N2 virus was detected in poultry farms in Western Canada at the end of November. The same strain (with identical genetic structure) was then detected in free-living wild birds that had died prior to December 8 of unrelated causes in Whatcom County, Washington, USA in an area contiguous with the index Canadian location. A gyrfalcon (Falco rusticolus) that had hunted and fed on an American wigeon (Anas americana) on December 6 in the same area and died two days later, tested positive for the Eurasian origin HPAI H5N8. Subsequently, an Active Surveillance Program using hunter-harvest waterfowl in Washington and Oregon detected ten HPAI H5 viruses, of three different subtypes (four H5N2, three H5N8 and three H5N1) with 4 segments in common (HA, PB2, NP and MA). In addition, a mortality-based Passive Surveillance Program detected 18 HPAI (14 H5N2 and four H5N8) cases from Idaho, Kansas, Oregon, Minnesota, Montana, Washington and Wisconsin. Comparatively, mortality-based passive surveillance appears to be detecting these HPAI infections at a higher rate than active surveillance during the period following initial introduction into the US.
West Nile virus (WNV) spread to the US western plains states in 2003, when a significant mortality event attributed to WNV occurred in Greater Sage-grouse ( Centrocercus urophasianus ). The role of avian species inhabiting sagebrush in the amplification of WNV in arid and semiarid regions of the North America is unknown. We conducted an experimental WNV challenge study in Vesper Sparrows ( Pooecetes gramineus ), a species common to sagebrush and grassland habitats found throughout much of North America. We found Vesper Sparrows to be moderately susceptible to WNV, developing viremia considered sufficient to transmit WNV to feeding mosquitoes, but the majority of birds were capable of surviving infection and developing a humoral immune response to the WNV nonstructural 1 and envelope proteins. Despite clearance of viremia, after 6 mo, WNV was detected molecularly in three birds and cultured from one bird. Surviving Vesper Sparrows were resistant to reinfection 6 mo after the initial challenge. Vesper sparrows could play a role in the amplification of WNV in sagebrush habitat and other areas of their range, but rapid clearance of WNV may limit their importance as competent amplification hosts of WNV.
In 2013 a novel avian influenza H7N9 virus was isolated from several critically ill patients in China, and infection with this virus has since caused more than 200 human deaths. Live poultry markets are the likely locations of virus exposure to humans. Peridomestic avian species also may play important roles in the transmission and maintenance of H7N9 at live poultry markets. We experimentally challenged wild European Starlings ( Sturnus vulgaris ) with the novel H7N9 virus and measured virus excretion, clinical signs, and infectious dose. We found that European Starlings can be infected with this virus when inoculated with relatively high doses, and we predict that infected birds excrete sufficient amounts of virus to transmit to other birds, including domestic chickens. Infected European Starlings showed no clinical signs or mortality after infection with H7N9. This abundant peridomestic bird may be a source of the novel H7N9 virus in live poultry markets and may have roles in virus transmission to poultry and humans.
No abstract available.
No abstract available
Wild waterfowl are primary reservoirs of avian influenza viruses (AIV). However the role of sea ducks in the ecology of avian influenza, and how that role differs from freshwater ducks, has not been examined. We obtained and analyzed sera from North Atlantic sea ducks and determined the seroprevalence in those populations. We also tested swab samples from North Atlantic sea ducks for the presence of AIV. We found relatively high serological prevalence (61%) in these sea duck populations but low virus prevalence (0.3%). Using these data we estimated that an antibody half-life of 141 weeks (3.2 years) would be required to attain these prevalences. These findings are much different than what is known in freshwater waterfowl and have implications for surveillance efforts, AIV in marine environments, and the roles of sea ducks and other long-lived waterfowl in avian influenza ecology.