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At least 1,009 records · Page 56Linked to original sources
USGS2014

Using cure models for analyzing the influence of pathogens on salmon survival

Parasites and pathogens influence the size and stability of wildlife populations, yet many population models ignore the population-level effects of pathogens. Standard survival analysis methods (e.g., accelerated failure time models) are used to assess how survival rates are influenced by disease. However, they assume that each individual is equally susceptible and will eventually experience the event of interest; this assumption is not typically satisfied with regard to pathogens of wildlife populations. In contrast, mixture cure models, which comprise logistic regression and survival analysis components, allow for different covariates to be entered into each part of the model and provide better predictions of survival when a fraction of the population is expected to survive a disease outbreak. We fitted mixture cure models to the host–pathogen dynamics of Chinook Salmon Oncorhynchus tshawytscha and Coho Salmon O. kisutch and the myxozoan parasite Ceratomyxa shasta . Total parasite concentration, water temperature, and discharge were used as covariates to predict the observed parasite-induced mortality in juvenile salmonids collected as part of a long-term monitoring program in the Klamath River, California. The mixture cure models predicted the observed total mortality well, but some of the variability in observed mortality rates was not captured by the models. Parasite concentration and water temperature were positively associated with total mortality and the mortality rate of both Chinook Salmon and Coho Salmon. Discharge was positively associated with total mortality for both species but only affected the mortality rate for Coho Salmon. The mixture cure models provide insights into how daily survival rates change over time in Chinook Salmon and Coho Salmon after they become infected with C. shasta .

Oregon, California↗
USGS1995

Mycotoxin-induced disease in captive whooping cranes (Grus americana) and sandhill cranes (Grus canadensis)

In 1987, an epizootic in cranes at the Patuxent Wildlife Research Center, Laurel, Maryland, USA, caused illness in 80% of 300 captive whooping cranes (Grus americana) and sandhill cranes (Grus canadensis) and death of 15 of these cranes. Gross pathology findings were inconclusive and consisted of dehydration, atrophy of fat, renal insufficiency, and small spleens. Extensive testing resulted in isolation of Fusarium sp. mold from constituents of the grain-based diet. Low levels of two mycotoxins, T2 (1-2 ppm) and deoxynivalenol (0.4 ppm), were isolated from the pelleted feed.

Maryland↗
USGS2012

Prevalence, environmental loading, and molecular characterization of Cryptosporidium and Giardia</i isolates from domestic and wild animals along the Central California Coast

The risk of disease transmission from waterborne protozoa is often dependent on the origin (e.g., domestic animals versus wildlife), overall parasite load in contaminated waterways, and parasite genotype, with infections being linked to runoff or direct deposition of domestic animal and wildlife feces. Fecal samples collected from domestic animals and wildlife along the central California coast were screened to (i) compare the prevalence and associated risk factors for fecal shedding of Cryptosporidium and Giardia species parasites, (ii) evaluate the relative importance of animal host groups that contribute to pathogen loading in coastal ecosystems, and (iii) characterize zoonotic and host-specific genotypes. Overall, 6% of fecal samples tested during 2007 to 2010 were positive for Cryptosporidium oocysts and 15% were positive for Giardia cysts. Animal host group and age class were significantly associated with detection of Cryptosporidium and Giardia parasites in animal feces. Fecal loading analysis revealed that infected beef cattle potentially contribute the greatest parasite load relative to other host groups, followed by wild canids. Beef cattle, however, shed host-specific, minimally zoonotic Cryptosporidium and Giardia duodenalis genotypes, whereas wild canids shed potentially zoonotic genotypes, including G. duodenalis assemblages A and B. Given that the parasite genotypes detected in cattle were not zoonotic, the public health risk posed by protozoan parasite shedding in cattle feces may be lower than that posed by other animals, such as wild canids, that routinely shed zoonotic genotypes.

California↗
USGS2012

Blackrock: biological hotspot and hotbed of collaboration

Amphibian decline is a problem of global importance, with over 40 percent of species considered at risk. This phenomenon is not limited to the tropics or to other countries; amphibian species in the United States are also declining, contributing to the larger global phenomenon. For example, in Wyoming, the Wyoming toad has been extirpated in the wild and the boreal toad is a species of special concern. Habitat loss (especially of wetlands) and disease are two examples of perturbations contributing to amphibian decline. Wetlands harbor a variety of wildlife from large ungulates to amphibians the size of a U.S. quarter. Because many amphibians depend on wetlands for breeding, feeding, and rearing young, the availability of wetlands is important to maintaining amphibian diversity and presence across suitable habitat.

Report↗
USGS2020

Threats posed by the Fungal Kingdom to humans, wildlife, and agriculture

The Fungal Kingdom includes at least six million eukaryotic species and is remarkable with respect to its profound impact on global health, biodiversity, ecology, agriculture, manufacturing, and biomedical research. Approximately 625 fungal species have been reported to infect vertebrates, 200 of which can be human-associated, either as commensals and members of our microbiome or as pathogens that cause infectious diseases. These organisms pose a growing threat to human health with the global increase in the incidence of invasive fungal infections, prevalence of fungal allergy, and the evolution of fungal pathogens resistant to some or all current classes of antifungals. More broadly, there has been an unprecedented and worldwide emergence of fungal pathogens impacting animal and plant biodiversity. Approximately 8,000 species of fungi and Oomycetes are associated with plant disease. Indeed, across agriculture, such fungal diseases of plants include new devastating epidemics of trees and jeopardize food security worldwide by causing epidemics in staple and commodity crops that feed billions. Further, ingestion of mycotoxins contributes to ill health and causes cancer. Coordinated international research efforts, enhanced technology translation, and greater policy outreach by scientists are needed to more fully understand the biology and drivers that underlie the emergence of fungal diseases and to mitigate against their impacts. Here, we focus on poignant examples of emerging fungal threats in each of three areas: human health, wildlife biodiversity, and food security.

mBio↗
USGS2024

Metagenomic sequencing sheds light on microbes putatively associated with pneumonia-related fatalities of white-tailed deer (Odocoileus virginianus)

With emerging infectious disease outbreaks in human, domestic and wild animal populations on the rise, improvements in pathogen characterization and surveillance are paramount for the protection of human and animal health, as well as the conservation of ecologically and economically important wildlife. Genomics offers a range of suitable tools to meet these goals, with metagenomic sequencing facilitating the characterization of whole microbial communities associated with emerging and endemic disease outbreaks. Here, we use metagenomic sequencing in a case-control study to identify microbes in lung tissue associated with newly observed pneumonia-related fatalities in 34 white-tailed deer ( Odocoileus virginianus ) in Wisconsin, USA. We identified 20 bacterial species that occurred in more than a single individual. Of these, only Clostridium novyi was found to substantially differ (in number of detections) between case and control sample groups; however, this difference was not statistically significant. We also detected several bacterial species associated with pneumonia and/or other diseases in ruminants ( Mycoplasma ovipneumoniae , Trueperella pyogenes , Pasteurella multocida , Anaplasma phagocytophilum , Fusobacterium necrophorum ); however, these species did not substantially differ between case and control sample groups. On average, we detected a larger number of bacterial species in case samples than controls, supporting the potential role of polymicrobial infections in this system. Importantly, we did not detect DNA of viruses or fungi, suggesting that they are not significantly associated with pneumonia in this system. Together, these results highlight the utility of metagenomic sequencing for identifying disease-associated microbes. This preliminary list of microbes will help inform future research on pneumonia-associated fatalities of white-tailed deer.

Microbial Genomics↗
USGS2023

Potential effects of habitat change on migratory bird movements and avian influenza transmission in the East Asian-Australasian Flyway

Wild waterbirds, and especially wild waterfowl, are considered to be a reservoir for avian influenza viruses, with transmission likely occurring at the agricultural-wildlife interface. In the past few decades, avian influenza has repeatedly emerged in China along the East Asian-Australasian Flyway (EAAF), where extensive habitat conversion has occurred. Rapid environmental changes in the EAAF, especially distributional changes in rice paddy agriculture, have the potential to affect both the movements of wild migratory birds and the likelihood of spillover at the agricultural-wildlife interface. To begin to understand the potential implications such changes may have on waterfowl and disease transmission risk, we created dynamic Brownian Bridge Movement Models (dBBMM) based on waterfowl telemetry data. We used these dBBMM models to create hypothetical scenarios that would predict likely changes in waterfowl distribution relative to recent changes in rice distribution quantified through remote sensing. Our models examined a range of responses in which increased availability of rice paddies would drive increased use by waterfowl and decreased availability would result in decreased use, predicted from empirical data. Results from our scenarios suggested that in southeast China, relatively small decreases in rice agriculture could lead to dramatic loss of stopover habitat, and in northeast China, increases in rice paddies should provide new areas that can be used by waterfowl. Finally, we explored the implications of how such scenarios of changing waterfowl distribution may affect the potential for avian influenza transmission. Our results provide advance understanding of changing disease transmission threats by incorporating real-world data that predicts differences in habitat utilization by migratory birds over time.

Diversity↗
USGS1945

Tularemia, an animal-borne disease

the disease tularemia continues to be of such importance in the United States that the Fish and Wildlife Service is constantly receiving requests for information on its nature and on the procedure recommended by field representatives of the Service in their work wiht the public. Such information is summarized in this leaflet. the information on human infections presented and the recommendations made have been endorsed by the United States Public Health Service.

Wildlife Leaflet↗
USGS1984

Disseminated visceral coccidiosis in sandhill cranes

Disseminated visceral coccidiosis (DVC) caused by Eimeria spp was first recognized as a disease entity in captive sandhill cranes (Grus canadensis) and whooping cranes (G americana) at the Patuxent Wildlife Research Center. Because cranes produced at the Center are reintroduced to the wild to augment wild populations, studies involving both experimentally induced and natural infections were initiated to determine the potential or actual occurrence of DVC in wild Gruidae. Nine sandhill cranes dosed orally with eimerian oocysts of wild origin developed lesions characteristic of DVC. Extraintestinal granulomas associated with developing schizonts were found in 6 birds. Similar lesions were observed in wild sandhill cranes throughout parts of midwestern United States, Alaska, and Saskatchewan. These studies revealed the wide geographic distribution and the high frequency of occurrence of DVC in wild cranes.

Journal of the American Veterinary Medical Associa↗
USGS2005

Prevalence of pox-like lesions and malaria in forest bird communitites on leeward Mauna Loa volcano, Hawaii

Introduced avian pox virus and malaria have had devastating impacts on native Hawaiian forest birds, yet little has been published about their prevalence and distribution in forest bird communities outside of windward Hawaii Island. We surveyed native and non-native forest birds for these two diseases at three different elevations on leeward Mauna Loa Volcano at the Kona Forest Unit of Hakalau Forest National Wildlife Refuge. Prevalence of malaria by both serology and microscopy varied by elevation and ranged from 28% at 710 m to 13% at 1830 m. Prevalence of pox-like lesions also varied by altitude, ranging in native species from 10% at 710 m to 2% at 1830 m. Native species at all elevations had the highest prevalence of malarial antibody and pox-like lesions. By contrast, pox-like lesions were not detected in individuals of four non-native species and only 5% of Japanese White-eye ( Zosterops japonicus ) was positive for malaria. A significantly high proportion of birds with pox-like lesions also had serological evidence of concurrent, chronic malarial infections, suggesting an interaction between these diseases, dual transmission of both diseases by the primary mosquito vector ( Culex quinquefasciatus ) or complete recovery of some pox-infected birds without loss of toes. Results from this study document high prevalence of malaria and pox at this refuge. Development of effective disease control strategies will be important for restoration of remnant populations of the endangered ‘Akiapola‘au ( Hemignathus munroi ), Hawaii Creeper ( Oreomystis mana ), and Hawaii ‘Akepa ( Loxops coccineus coccineus ) that still occur on the refuge.

Hawai'i↗
USGS1998

Causes and rates of mortality of swift foxes in western Kansas

Knowledge of mortality factors is important for developing strategies to conserve the swift fox (Vulpes velox), a species being considered for listing under the Endangered Species Act, but available information about swift fox mortality is inadequate. We used radiotelemetry techniques to examine the magnitude and causes of mortality of swift fox populations in 2 study areas in western Kansas. One study area was predominantly cropland, the other rangeland. Mortality rates, calculated using Kaplan-Meier estimation techniques in a staggered entry design, were 0.55 ?? 0.08 (5 ?? SE) for adult and 0.67 ?? 0.08 for juvenile swift foxes. We did not detect differences between study areas in mortality rates for adults or juveniles. Predation by coyotes (Canis latrans) was the major cause of mortality for adult and juvenile swift foxes in both study areas, and vehicle collision was an important mortality factor for juveniles in the cropland study area. No mortality was attributed to starvation or disease.

Journal of Wildlife Management↗
USGS2016

Effects of repeated simulated removal activities on feral swine movements and space use

Abundance and distribution of feral swine ( Sus scrofa ) in the USA have increased dramatically during the last 30 years. Effective measures are needed to control and eradicate feral swine populations without displacing animals over wider areas. Our objective was to investigate effects of repeated simulated removal activities on feral swine movements and space use. We analyzed location data from 21 feral swine that we fitted with Global Positioning System harnesses in southern MO, USA. Various removal activities were applied over time to eight feral swine before lethal removal, including trapped-and-released, chased with dogs, chased with hunter, and chased with helicopter. We found that core space-use areas were reduced following the first removal activity, whereas overall space-use areas and diurnal movement distances increased following the second removal activity. Mean geographic centroid shifts did not differ between pre- and post-periods for either the first or second removal activities. Our information on feral swine movements and space use precipitated by human removal activities, such as hunting, trapping, and chasing with dogs, helps fill a knowledge void and will aid wildlife managers. Strategies to optimize management are needed to reduce feral swine populations while preventing enlarged home ranges and displacing individuals, which could lead to increased disease transmission risk and human-feral swine conflict in adjacent areas.

European Journal of Wildlife Research↗
USGS2010

Chronic wasting disease (CWD) susceptibility of several North American rodents that are sympatric with cervid CWD epidemics

Chronic wasting disease (CWD) is a highly contagious always fatal neurodegenerative disease that is currently known to naturally infect only species of the deer family, Cervidae. CWD epidemics are occurring in free-ranging cervids at several locations in North America, and other wildlife species are certainly being exposed to infectious material. To assess the potential for transmission, we intracerebrally inoculated four species of epidemic-sympatric rodents with CWD. Transmission was efficient in all species; the onset of disease was faster in the two vole species than the two Peromyscus spp. The results for inocula prepared from CWD-positive deer with or without CWD-resistant genotypes were similar. Survival times were substantially shortened upon second passage, demonstrating adaptation. Unlike all other known prion protein sequences for cricetid rodents that possess asparagine at position 170, our red-backed voles expressed serine and refute previous suggestions that a serine in this position substantially reduces susceptibility to CWD. Given the scavenging habits of these rodent species, the apparent persistence of CWD prions in the environment, and the inevitable exposure of these rodents to CWD prions, our intracerebral challenge results indicate that further investigation of the possibility of natural transmission is warranted. Copyright ?? 2010, American Society for Microbiology. All Rights Reserved.

Journal of Virology↗
USGS2025

Unintended indirect effects limit elk productivity from supplemental feeding in the Greater Yellowstone Ecosystem

The widespread practice of supplemental feeding, a bottom-up forcing of resource availability, is intended to improve wildlife population health and survival. However, supplemental feeding could trigger indirect effects by altering predation rates and disease dynamics. We investigated the effects of feeding on three key elk ( Cervus canadensis ) population productivity metrics (calf:cow ratios, annual change in elk density, and harvestable surplus) across 13 regions in the Greater Yellowstone Ecosystem (GYE) over 26 years. Incorporating previous population size, climate, predator, and harvest data in a Bayesian regression framework revealed new insights about elk productivity metrics in the GYE. Supplemental feeding was associated with increased calf:cow ratios (4.9%) but was not substantially related to changes in elk density and harvestable surplus, which are both management targets. Notably, the feeding effect on calf:cow ratios appeared to be offset by increased wolf ( Canis lupus ) and grizzly bear ( Ursus arctos horribilis ) predation. We hypothesize that increased elk productivity resulting from supplemental feeding is primarily transferred to predator and pathogen trophic levels in this system with limited observed effects on elk abundance and harvestable surplus. Anthropogenic food resources may have unintended indirect consequences on other trophic levels that potentially limit the direct impacts of feeding.

Idaho, Montana, Wyoming↗