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USGS2021

Landscape features fail to explain spatial genetic structure in white-tailed deer across Ohio, USA

Landscape features influence wildlife movements across spatial scales and have the potential to influence the spread of disease. Chronic wasting disease (CWD) is a fatal prion disease affecting members of the family Cervidae, particularly white-tailed deer ( Odocoileus virginianus ), and the first positive CWD case in a wild deer in Ohio, USA, was recorded in 2020. Landscape genetics approaches are increasingly used to better understand potential pathways for CWD spread in white-tailed deer, but little is known about genetic structure of white-tailed deer in Ohio. The objectives of our study were to evaluate spatial genetic structure in white-tailed deer across Ohio and compare the support for isolation by distance (IBD) and isolation by landscape resistance (IBR) models in explaining this structure. We collected genetic data from 619 individual deer from 24 counties across Ohio during 2007–2009. We used microsatellite genotypes from 619 individuals genotyped at 11 loci and haplotypes from a 547-base pair fragment of the mitochondrial DNA control region. We used spatial and non-spatial genetic clustering tests to evaluate genetic structure in both types of genetic data and empirically optimized landscape resistance surfaces to compare IBD and IBR using microsatellite data. Non-spatial genetic clustering tests failed to detect spatial genetic structure, whereas spatial genetic clustering tests indicated subtle spatial genetic structure. The IBD model consistently outperformed IBR models that included land cover, traffic volume, and streams. Our results indicated widespread genetic connectivity of white-tailed deer across Ohio and negligible effects of landscape features. These patterns likely reflect some combination of minimal resistive effects of landscape features on white-tail deer movement in Ohio and the effects of regional recolonization or translocation. We encourage continued CWD surveillance in Ohio, particularly in the proximity of confirmed cases.

Ohio↗

USGS1992

Chemical ions affect survival of avian cholera organisms in pondwater

Avian cholera ( Pasteurella multocida ) is a major disease of wild waterfowl, but its epizootiology remains little understood. Consequently, we examined whether chemical ions affected survival of avian cholera organisms in water collected from the Nebraska Rainwater Basin where avian cholera is enzootic. We tested the response of P. multocida to ammonium (NH 4 ), calcium (Ca), magnesium (Mg), nitrate (NO 3 ), and ortho-phosphate (PO 4 ) ions individually and in combination using a fractional factorial design divided into 4 blocks. High concentrations of Ca and Mg, singly or in combination, increased survival of P. multocida organisms (P < 0.001). We developed a survival index to predict whether or not specific ponds could be "problem" or "nonproblem" avian cholera sites based on concentrations of these ions in the water.

Nebraska↗

USGS1978

Metabolic indicators of habitat differences in four Minnesota deer populations

Blood samples were collected from 40 white-tailed deer ( Odocoileus virginianus ) from 4 winter yards in northeastern Minnesota from 17 March 1974 through 23 April 1975. The results of 26 blood assays were examined for the effects of age, sex, capture date, capture method, disease and location. Age-related effects were found for serum chloride, calcium, gamma globulin, creatine phosphokinase (CPK), lactic dehydrogenase (LDH), and alkaline phosphatase. The only sex difference was lower CPK in males. Date of collection effects were found for erythrocyte count, mean corpuscular volume (MCV), serum glucose, and nonesterified fatty acids (NEF A). Capture method affected serum glucose, acid base balance, and serum enzymes. Effects related primarily to capture location or habitat differences were found for erythrocyte count, MCV, mean corpuscular hemoglobin concentration (MCHC), serum urea, cholesterol, LDH, thyroxine, and NEF A. Animals whose assays indicated the poorest nutritional status inhabited wintering areas with the oldest vegetation. Habitat differences can be detected by measuring the physiological status of the local animal populations.

Minnesota↗

USGS2022

Highly pathogenic avian influenza is an emerging disease threat to wild birds in North America

Prior to the emergence of the A/goose/Guangdong/1/1996 (Gs/GD) H5N1 influenza A virus, the long-held and well-supported paradigm was that highly pathogenic avian influenza (HPAI) outbreaks were restricted to poultry, the result of cross-species transmission of precursor viruses from wild aquatic birds that subsequently gained pathogenicity in domestic birds. Therefore, management agencies typically adopted a prevention, control, and eradication strategy that included strict biosecurity for domestic bird production, isolation of infected and exposed flocks, and prompt depopulation. In most cases, this strategy has proved sufficient for eradicating HPAI. Since 2002, this paradigm has been challenged with many detections of viral descendants of the Gs/GD lineage among wild birds, most of which have been associated with sporadic mortality events. Since the emergence and evolution of the genetically distinct clade 2.3.4.4 Gs/GD lineage HPAI viruses in approximately 2010, there have been further increases in the occurrence of HPAI in wild birds and geographic spread through migratory bird movement. A prominent example is the introduction of clade 2.3.4.4 Gs/GD HPAI viruses from East Asia to North America via migratory birds in autumn 2014 that ultimately led to the largest outbreak of HPAI in the history of the United States. Given the apparent maintenance of Gs/GD lineage HPAI viruses in a global avian reservoir; bidirectional virus exchange between wild and domestic birds facilitating the continued adaptation of Gs/GD HPAI viruses in wild bird hosts; the current frequency of HPAI outbreaks in wild birds globally, and particularly in Eurasia where Gs/GD HPAI viruses may now be enzootic; and ongoing dispersal of AI viruses from East Asia to North America via migratory birds, HPAI now represents an emerging disease threat to North American wildlife. This recent paradigm shift implies that management of HPAI in domestic birds alone may no longer be sufficient to eradicate HPAI viruses from a given country or region. Rather, agencies managing wild birds and their habitats may consider the development or adoption of mitigation strategies to minimize introductions to poultry, to reduce negative impacts on wild bird populations, and to diminish adverse effects to stakeholders using wildlife resources. The main objective of this review is, therefore, to provide information that will assist wildlife managers in developing mitigation strategies or approaches for dealing with outbreaks of Gs/GD HPAI in wild birds in the form of preparedness, surveillance, research, communications, and targeted management actions. Resultant outbreak response plans and actions may represent meaningful steps of wildlife managers toward the use of collaborative and multi-jurisdictional One Health approaches when it comes to the detection, investigation, and mitigation of emerging viruses at the human-domestic animal-wildlife interface.

Journal of Wildlife Management↗

USGS2017

Ecotypic variation in population dynamics of reintroduced bighorn sheep

Selection of bighorn sheep ( Ovis canadensis ) for translocation historically has been motivated by preservation of subspecific purity rather than by adaptation of source stocks to similar environments. Our objective was to estimate cause‐specific, annual, and age‐specific mortality of introduced bighorn sheep that originated at low elevations in southern British Columbia, Canada (BC ecotype), or in the Missouri River Breaks region of central Montana, USA (MT ecotype). In North Dakota, USA, mortality was similar and typically low for adult female bighorn sheep from Montana (0.09 ± 0.029 [SE]) and British Columbia (0.08 ± 0.017) during 2000–2016. Median life expectancy was 11 years for females that reached adulthood (2 yrs old); however, mortality accelerated with age and reached 86% by age 16. Mortalities resulted primarily from low rates of predation, disease, accidents, and unknown natural causes (<0.04 [upper 90% CI]). Similar survival rates of female bighorn sheep from female bighorn sheep from British Columbia and Montana, coupled with greater recruitment of bighorn sheep from Montana, resulted in a greater projected rate of increase for the MT ecotype ( λ = 1.21) than for the BC ecotype (1.02), and a more youthful age structure. These results support translocation of bighorn sheep from areas that are environmentally similar to areas that will be stocked. Potential benefits include more rapid population growth, greater resilience to and more rapid recovery from density‐independent losses, an increased possibility that rapidly growing populations will expand into adjacent habitat, increased hunter opportunity, increased connectivity among herds, and a more complete restoration of ecosystem processes.

Journal of Wildlife Management↗

USGS2014

Distance to human populations influences epidemiology of respiratory disease in desert tortoises

We explored variables likely to affect health of Agassiz's desert tortoises (Gopherus agassizii) in a 1,183-km2 study area in the central Mojave Desert of California between 2005 and 2008. We evaluated 1,004 tortoises for prevalence and spatial distribution of 2 pathogens, Mycoplasma agassizii and M. testudineum, that cause upper respiratory tract disease. We defined tortoises as test-positive if they were positive by culture and/or DNA identification or positive or suspect for specific antibody for either of the two pathogens. We used covariates of habitat (vegetation, elevation, slope, and aspect), tortoise size and sex, distance from another test-positive tortoise, and anthropogenic variables (distances to roads, agricultural areas, playas, urban areas, and centroids of human-populated census blocks). We used both logistic regression models and regression trees to evaluate the 2 species of Mycoplasma separately. The prevalence of test-positive tortoises was low: 1.49% (15/1,004) for M. agassizii and 2.89% (29/1,004) for M. testudineum. The spatial distributions of test-positive tortoises for the 2 Mycoplasma species showed little overlap; only 2 tortoises were test-positive for both diseases. However, the spatial distributions did not differ statistically between the 2 species. We consistently found higher prevalence of test-positive tortoises with shorter distances to centroids of human-populated census blocks. The relationship between distance to human-populated census blocks and tortoises that are test-positive for M. agassizii and potentially M. testudineum may be related to release or escape of captive tortoises because the prevalence of M. agassizii in captive tortoises is high. Our findings have application to other species of chelonians where both domestic captive and wild populations exist. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Journal of Wildlife Management↗

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↗

USGS2006

Utility of R0 as a predictor of disease invasion in structured populations

Early theoretical work on disease invasion typically assumed large and well-mixed host populations. Many human and wildlife systems, however, have small groups with limited movement among groups. In these situations, the basic reproductive number, R 0 , is likely to be a poor predictor of a disease pandemic because it typically does not account for group structure and movement of individuals among groups. We extend recent work by combining the movement of hosts, transmission within groups, recovery from infection and the recruitment of new susceptibles into a stochastic model of disease in a host metapopulation. We focus on how recruitment of susceptibles affects disease invasion and how population structure can affect the frequency of superspreading events (SSEs). We show that the frequency of SSEs may decrease with the reduced movement and the group sizes due to the limited number of susceptible individuals available. Classification tree analysis of the model results illustrates the hierarchical nature of disease invasion in host metapopulations. First, the pathogen must effectively transmit within a group ( R 0 >1), and then the pathogen must persist within a group long enough to allow for movement among the groups. Therefore, the factors affecting disease persistence—such as infectious period, group size and recruitment of new susceptibles—are as important as the local transmission rates in predicting the spread of pathogens across a metapopulation.

Journal of the Royal Society Interface↗

USGS2015

Identifying priority chronic wasting disease surveillance areas for mule deer in Montana

Chronic wasting disease (CWD) is a fatal prion disease that affects a variety of ungulate species including mule deer ( Odocoileus hemionus ). As of 2014, no CWD cases had been reported in free-ranging ungulates in Montana. However, nearby cases in Canada, Wyoming, and the Dakotas indicated that the disease was encroaching on Montana's borders. Mule deer are native and common throughout Montana, and they represent a significant portion of the total hunter-harvested cervids in the state. The arrival of CWD in Montana may have significant ecosystem and socioeconomic impacts as well as potential consequences for wildlife management. We used 18,879 mule deer locations from 892 individual deer collected during 1975–2011 and modeled habitat selection for 7 herds in 5 of the 7 wildlife management regions in Montana. We estimated resource selection functions (RSF) in a Bayesian framework to predict summer and winter habitat preferences for mule deer. We estimated deer abundance from flyover counts for each region, and used the RSF predictions as weights to distribute the deer across the region. We then calculated the distance to the nearest known infected herds. We predicted areas of high risk of CWD infection in mule deer as areas with densities above the median density estimate and within the lowest quartile of distances to known infected herds. We identified these areas, the southeast corner of Montana and the north-central border near Alberta and Saskatchewan, as priority areas for CWD surveillance and management efforts.

Montana↗

USGS2020

Validation of laboratory tests for infectious diseases in wild mammals: Review and recommendations

Evaluation of the diagnostic sensitivity (DSe) and specificity (DSp) of tests for infectious diseases in wild animals is challenging, and some of the limitations may affect compliance with the OIE-recommended test validation pathway. We conducted a methodologic review of test validation studies for OIE-listed diseases in wild mammals published between 2008 and 2017 and focused on study design, statistical analysis, and reporting of results. Most published papers addressed Mycobacterium bovis infection in one or more wildlife species. Our review revealed limitations or missing information about sampled animals, identification criteria for positive and negative samples (case definition), representativeness of source and target populations, and species in the study, as well as information identifying animals sampled for calculations of DSe and DSp as naturally infected captive, free-ranging, or experimentally challenged animals. The deficiencies may have reflected omissions in reporting rather than design flaws, although lack of random sampling might have induced bias in estimates of DSe and DSp. We used case studies of validation of tests for hemorrhagic diseases in deer and white-nose syndrome in hibernating bats to demonstrate approaches for validation when new pathogen serotypes or genotypes are detected and diagnostic algorithms are changed, and how purposes of tests evolve together with the evolution of the pathogen after identification. We describe potential benefits of experimental challenge studies for obtaining DSe and DSp estimates, methods to maintain sample integrity, and Bayesian latent class models for statistical analysis. We make recommendations for improvements in future studies of detection test accuracy in wild mammals.

Journal of Veterinary Diagnostic Investigation↗

USGS2017

Winter habitat associations of eastern spotted skunks in Virginia

Eastern spotted skunk ( Spilogale putorius ) populations have declined throughout much of their range in the eastern United States over recent decades. Declines have been attributed to habitat loss or change, increased competition with sympatric mesocarnivore species, or disease. To better understand the extant distribution of spotted skunks in the Appalachian Mountains of western Virginia, USA, we used a detection-non-detection sampling approach using baited camera traps to evaluate the influence of landscape-level environmental covariates on spotted skunk detection probability and site occupancy. We conducted camera trap surveys at 91 sites from January to May in 2014 and 2015. Spotted skunk occupancy was associated with young-aged forest stands at lower elevations and more mature forest stands at higher elevations. Both land cover types in this region can be characterized as having complex forest structure, providing cover that varies with stand age, species composition, elevation, and management regime. Our results provide insight into factors that influence spotted skunk spatial distribution and habitat selection, information that can be used to generate conservation assessments and inform management decisions.

Virginia↗

USGS2014

Surveillance and monitoring of white-tailed deer for chronic wasting disease in the northeastern United States

Chronic wasting disease (CWD) is a prion disease that affects both wild and captive cervid populations. In the past 45 y, CWD has spread from northern Colorado to all bordering states, as well as the midwestern United States (Midwest) and northeastern United States (Northeast), Canada, and South Korea. Because CWD is a relatively new issue for wildlife management agencies in the Northeast, we surveyed a representative (e.g., cervid biologist, wildlife veterinarian) from 14 states to gain a better understanding of state-specific surveillance measures. Between 2002 and 2012, New York (37,093) and Pennsylvania (35,324) tested the greatest number of harvested white-tailed deer Odocoileus virginianus in the Northeast. Additionally, the 14 states surveyed have tested 121,730 harvested deer, or approximately 15,216/y, since CWD was first detected in 2005. The most common tissues used by agencies in the Northeast for testing were retropharyngeal lymph nodes, which have been determined to be the most reliable in detecting CWD in cervids. Understanding CWD surveillance efforts at a regional scale can help to provide guidance for the development of new surveillance plans or the improvement of existing ones. Furthermore, collaborations among state and regional agencies in the Northeast may attempt to identify deficiencies in surveillance by state or subregion.

Connecticut, Delaware, Maine, Maryland, Massachuse↗

USGS2021

Population structure, intergroup interaction, and human contact govern infectious disease impacts in mountain gorilla populations

Infectious zoonotic diseases are a threat to wildlife conservation and global health. They are especially a concern for wild apes, which are vulnerable to many human infectious diseases. As ecotourism, deforestation, and great ape field research increase, the threat of human-sourced infections to wild populations becomes more substantial and could result in devastating population declines. The endangered mountain gorillas ( Gorilla beringei beringei ) of the Virunga Massif in east-central Africa suffer periodic disease outbreaks and are exposed to infections from human-sourced pathogens. It is important to understand the possible risks of disease introduction and spread in this population and how human contact may facilitate disease transmission. Here we present and evaluate an individual-based, stochastic, discrete-time disease transmission model to predict epidemic outcomes and better understand health risks to the Virunga mountain gorilla population. To model disease transmission we have derived estimates for gorilla contact, interaction, and migration rates. The model shows that the social structure of gorilla populations plays a profound role in governing disease impacts with subdivided populations experiencing less than 25% of the outbreak levels of a single homogeneous population. It predicts that gorilla group dispersal and limited group interactions are strong factors in preventing widespread population-level outbreaks of infectious disease after such diseases have been introduced into the population. However, even a moderate amount of human contact increases disease spread and can lead to population-level outbreaks.

Virunga Massif↗

USGS2006

Comparison of methods used to diagnose generalized inflammatory disease in manatees (Trichechus manatus latirostris)

Manatees ( Trichechus manatus latirostris ) are afflicted with inflammatory and infectious disease secondary to human interaction, such as boat strike and entanglement, as well as “cold stress syndrome” and pneumonia. White-blood-cell count and fever, primary indicators of systemic inflammation in most species, are insensitive in diagnosing inflammatory disease in manatees. Acute phase-response proteins, such as haptoglobin and serum amyloid A, have proven to be sensitive measures of inflammation/infection in domestic large animal species. This study assessed diagnosis of generalized inflammatory disease by different methods including total white-blood-cell count, albumin: globulin ratio, gel electrophoresis analysis, C-reactive protein, alpha 1 acid glycoprotein, haptoglobin, fibrinogen, and serum amyloid A. Samples were collected from 71 apparently healthy and 27 diseased animals during diagnostic medical examination. Serum amyloid A, measured by ELISA, followed by albumin:globulin ratio, measured by plasma gel electrophoresis, were most sensitive in diagnosing inflammatory disease, with diagnostic sensitivity and specificity of approximately 90%. The reference interval for serum amyloid A is <10–50 μg/ml with an equivocal interval of 51–70 μg/ml. The reference interval for albumin:globulin ratio by plasma gel electrophoresis is 0.7–1.1. Albumin: globulin ratio, calculated using biochemical techniques, was not accurate due to overestimation of albumin by bromcresol green dye-binding methodology. Albumin:globulin ratio, measured by serum gel electrophoresis, has a low sensitivity of 15% due to the lack of fibrinogen in the sample. Haptoglobin, measured by hemoglobin titration, had a reference interval of 0.4–2.4 mg/ml, a diagnostic sensitivity of 60%, and a diagnostic specificity of 93%. The haptoglobin assay is significantly affected by hemolysis. Fibrinogen, measured by heat precipitation, has a reference interval of 100–400 mg/dl, a diagnostic sensitivity of 40%, and a diagnostic specificity of 95%.

Journal of Zoo and Wildlife Medicine↗

USGS2023

Gene expression reveals immune response strategies of naïve Hawaiian honeycreepers experimentally infected with introduced avian malaria

The unprecedented rise in the number of new and emerging infectious diseases in the last quarter century poses direct threats to human and wildlife health. The introduction to the Hawaiian archipelago of Plasmodium relictum and the mosquito vector that transmits the parasite has led to dramatic losses in endemic Hawaiian forest bird species. Understanding how mechanisms of disease immunity to avian malaria may evolve is critical as climate change facilitates increased disease transmission to high elevation habitats where malaria transmission has historically been low and the majority of the remaining extant Hawaiian forest bird species now reside. Here, we compare the transcriptomic profiles of highly susceptible Hawai‘i ‘amakihi ( Chlorodrepanis virens ) experimentally infected with P. relictum to those of uninfected control birds from a naïve high elevation population. We examined changes in gene expression profiles at different stages of infection to provide an in-depth characterization of the molecular pathways contributing to survival or mortality in these birds. We show that the timing and magnitude of the innate and adaptive immune response differed substantially between individuals that survived and those that succumbed to infection, and likely contributed to the observed variation in survival. These results lay the foundation for developing gene-based conservation strategies for Hawaiian honeycreepers by identifying candidate genes and cellular pathways involved in the pathogen response that correlate with a bird’s ability to recover from malaria infection.

Hawaii↗

USGS1995

Effects of canine parvovirus on gray wolves in Minnesota

Long-term effects of disease on wild animal population demography is not well documented. We studied a gray wolf (Canis lupus) population in a 2,060-km 2 area of Minnesota for 15 years to determine its response to canine parvovirus (CPV). The CPV had little effect ( P > 0.05) on wolf population size while epizootic during 1979-83. However, after CPV became enzootic, percentage of pups captured during summer-fall 1984-93 and changes in subsequent winter wolf numbers were each inversely related to the serological prevalence of CPV in wolves captured during July-November ( r 2 = 0.39 and 0.72, P = 0.05 and < 0.01, respectively). The CPV antibody prevalence in adult wolves increased to 87% in 1993 (r2 = 0.28, P = 0.05). However, because population level remained stable, CPV-induced mortality appeared to compensate for other mortality factors such as starvation. We -predict that the winter wolf population will decline when CPV prevalence in adults consistently exceeds 76%. The CPV may become important in limiting wolf populations.

Minnesota↗

USGS2000

Lead exposure in American black ducks after implementation of non-toxic shot

Lead poisoning from the ingestion of spent shotgun pellets has been recognized as an important disease of North American waterfowl since Bellrose's (1959) research >40 years ago. Nation-wide regulations banning the use of lead shot for waterfowl hunting were established in 1991. We compared the prevalence of lead exposure in American black ducks ( Anas rubripes ) wintering on 2 areas in Tennessee before (1986-88) and after the ban (1997-99) to assess the effect of the ban on lead shot on this species. Prevalence of elevated blood lead in black ducks declined by 44% from before (11.7% prevalence) to after (6.5% prevalence) the implementation of non-toxic shot. The reduction in lead exposure was pronounced in adult black ducks (from 14.3% to 5.3%). However, prevalence in lead exposure remained similar in juvenile black ducks (from 8.2% to 8.3%). Additional evidence from lead ingestion and lead poisoning mortality events also indicates that lead exposure has declined in waterfowl in the Mississippi flyway. We believe that lead ingestion will continue to decline, despite the persistence of lead shot in some wetlands. The impact of reduced lead exposure on waterfowl populations needs to be assessed.

Tennessee↗

USGS2024

Morbidity in California giant salamander (Dicamptodon ensatus Eschscholtz, 1833) caused by Euryhelmis sp. Poche, 1926 (Trematoda: Heterophyiidae)

In the fall of 2021, California Department of Fish and Wildlife reported larval and adult California giant salamanders ( Dicamptodon ensatus Eschscholtz, 1833) with skin lesions at multiple creeks in Santa Clara and Santa Cruz Counties, California, USA. Field signs in both stages included rough, lumpy textured skin, and larvae with tails that were disproportionately long, flat, wavy, and flaccid. Presence of large-bodied larvae suggested delayed metamorphosis, with some larvae having cloudy eyes and suspected blindness. To determine the cause of the disease, three first-of-the-year salamanders from one location were collected, euthanized with 20% benzocaine, and submitted for necropsy to the U.S. Geological Survey, National Wildlife Health Center. Upon gross examination, all salamanders were emaciated with no internal fat stores, and had multiple pinpoint to 1.5-mm diameter raised nodules in the skin over the body, including the head, gills, dorsum, ventrum, all four limbs, and the tail; one also had nodules in the oral cavity and tongue. Histologically all salamanders had multiple encysted metacercariae in the dermis, subcutis, and skeletal muscles of the head, body, and tail that were often associated with granulomatous and granulocytic inflammation and edema. A small number of encysted meta cercariae or empty cysts were present in the gills with minimal inflammation, and rarely in the kidney with no associated inflammation. Morphology of live metacercariae (Trematoda: Heterophyiidae), and sequencing of the 28S rRNA gene identified a species of Euryhelmis (Poche, 1926). Artificial digestion of a 1.65 g, decapitated, eviscerated carcass yielded 773 metacercariae, all of similar size and morphology as the live specimens. Based on these findings, the poor body condition of these salamanders was concluded to be due to heavy parasite burden. Environmental factors such as drought, increased temperature, and overcrowded conditions may be exacerbating parasite infections in these populations of salamander.

California↗