Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Pathogens”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
USGS2008

Dispersal of Culex quinquefasciatus (Diptera: Culicidae) in a Hawaiian rain forest

Introduced mosquito-borne pathogens avian malaria (Plasmodium relictum Grassi and Feletti) and avian pox virus (Avipoxvirus) have been implicated in the past extinctions and declines of Hawaiian avifauna and remain significant obstacles to the recovery and restoration of endemic Hawaiian birds. Effective management of avian disease will require extensive mosquito control efforts that are guided by the local ecology of the vector Culex quinquefasciatus Say (Diptera: Culicidae). During October and November 1997 and September through November 1998 five mark-release-recapture experiments with laboratory-reared Cx. quinquefasciatus were conducted in a native rain forest on Hawaii Island. Of the overall 66,047 fluorescent dye-marked and released females, 1,192 (1.8%) were recaptured in 43-52 CO2-baited traps operated for 10-12-d trapping periods. Recaptured mosquitoes were trapped in all directions and at distances up to 3 km from the release site. The cumulative mean distance traveled (MDTs) over the trapping period ranged from a high of 1.89 km after 11 d (September 1998) to a low of 0.81 km after 11 d (November 1998). Released mosquitoes moved predominately in a downwind direction and they seemed to use forestry roads as dispersal corridors. Applying an estimated MDT of 1.6 km to a geographical information system-generated map of the Hakalau Forest National Wildlife Refuge clearly demonstrated that the effective refuge area could be reduced 60% by mosquitoes infiltrating into managed refuge lands. These findings should have significant implications for the design of future refuges and development of effective mosquito-borne avian disease control strategies.

Journal of Medical Entomology↗
USGS2014

Effect of temperature on feeding period of larval blacklegged ticks (Acari: Ixodidae) on eastern fence lizards

Ambient temperature can influence tick development time, and can potentially affect tick interactions with pathogens and with vertebrate hosts. We studied the effect of ambient temperature on duration of attachment of larval blacklegged ticks, Ixodes scapularis Say, to eastern fence lizards, Sceloporus undulatus (Bose & Daudin). Feeding periods of larvae that attached to lizards under preferred temperature conditions for the lizards (WARM treatment: temperatures averaged 36.6°C at the top of the cage and 25.8°C at the bottom, allowing behavioral thermoregulation) were shorter than for larvae on lizards held under cool conditions (COOL treatment temperatures averaged 28.4°C at top of cage and 24.9°C at the bottom). The lizards were infested with larvae four times at roughly monthly intervals. Larval numbers successfully engorging and dropping declined and feeding period was longer after the first infestation.

Journal of Medical Entomology↗
USGS2019

Influenza A prevalence and subtype diversity in migrating teal sampled along the United States Gulf Coast

Wild birds in the order Anseriformes are important reservoirs for influenza A viruses (IAV); however, IAV prevalence and subtype diversity may vary by season, even at the same location. To better understand the ecology of IAV during waterfowl migration through the Gulf Coast of the United States (Louisiana and Texas), surveillance of blue-winged (Spatula discors) and American green-winged (Anas carolinensis) teal was conducted annually during the spring (live-capture; 2012-2017) and fall (hunter-harvested; 2007-2017) at times inferred to coincide with northward and southward movements, respectively, for these waterfowl species. During spring migration, 266 low pathogenicity (LP) IAV positive samples were recovered from 7,547 paired cloacal/oropharyngeal (COP) samples (prevalence: 3.5%; annual range: 1.3%-8.4%). During fall migration, 650 LP IAV positive samples were recovered from 9,493 COP samples (prevalence: 6.8%; annual range: 0.4%-23.5%). Overall, 34 and 20 different IAV subtypes were recovered during fall and spring sampling, respectively. Consistent with previous results for fall migrating ducks, H3 and H4 HA subtypes were most common; however, H4 subtype viruses predominated every year. This is in contrast to the predominance of LP H7 and H10 HA subtype viruses in both species during spring. The N6 and N8 NA subtypes, which were usually associated with H4, were most common during fall; the N6 subtype was not recovered in the spring. These consistent seasonal trends in IAV subtype detection in both species are currently not understood and highlight the need for further research regarding potential drivers of spatiotemporal patterns of infection such as population immunity.

Avian Diseases↗
USGS2010

Migration of waterfowl in the east asian flyway and spatial relationship to HPAI H5N1 outbreaks

Poyang Lake is situated within the East Asian Flyway, a migratory corridor for waterfowl that also encompasses Guangdong Province, China, the epicenter of highly pathogenic avian influenza (HPAI) H5N1. The lake is the largest freshwater body in China and a significant congregation site for waterfowl; however, surrounding rice fields and poultry grazing have created an overlap with wild waterbirds, a situation conducive to avian influenza transmission. Reports of HPAI H5N1 in healthy wild ducks at Poyang Lake have raised concerns about the potential of resilient free-ranging birds to disseminate the virus. Yet the role wild ducks play in connecting regions of HPAI H5N1 outbreak in Asia is hindered by a lack of information about their migratory ecology. During 2007-08 we marked wild ducks at Poyang Lake with satellite transmitters to examine the location and timing of spring migration and identify any spatiotemporal relationship with HPAI H5N1 outbreaks. Species included the Eurasian wigeon ( Anas penelope ), northern pintail ( Anas acuta ), common teal ( Anas crecca ), falcated teal ( Anas falcata ), Baikal teal ( Anas formosa ), mallard ( Anas platyrhynchos ), garganey ( Anas querquedula ), and Chinese spotbill ( Anas poecilohyncha ). These wild ducks (excluding the resident mallard and Chinese spotbill ducks) followed the East Asian Flyway along the coast to breeding areas in northern China, eastern Mongolia, and eastern Russia. None migrated west toward Qinghai Lake (site of the largest wild bird epizootic), thus failing to demonstrate any migratory connection to the Central Asian Flyway. A newly developed Brownian bridge spatial analysis indicated that HPAI H5N1 outbreaks reported in the flyway were related to latitude and poultry density but not to the core migration corridor or to wetland habitats. Also, we found a temporal mismatch between timing of outbreaks and wild duck movements. These analyses depend on complete or representative reporting of outbreaks, but by documenting movements of wild waterfowl, we present ecological knowledge that better informs epidemiological investigations seeking to explain and predict the spread of avian influenza viruses. ?? 2010 American Association of Avian Pathologists.

Avian Diseases↗
USGS2025

Avian influenza infection and antibodies not identified in eastern wild turkeys (Meleagris gallopavo silvestris) sampled on the Delmarva Peninsula

Although highly pathogenic avian influenza presents a notable threat to domestic turkeys ( Meleagris gallopavo domesticus ), there have been minimal infections identified in wild turkeys ( Meleagris gallopavo ) across the United States. Indeed, recent infections in wild turkeys have either been linked back to or suspected to be the result of spillback from nearby infected domestic turkeys. This study presents avian influenza sampling data for Eastern wild turkeys ( Meleagris gallopavo silvestris ) across the Maryland portion of the Delmarva Peninsula, in the winter of 2023–2024, with an objective of identifying any circulating influenza A viruses (IAVs), as well as determining the extent of previous exposure to IAVs in this population. We collected swab samples from 36 female wild turkeys. No IAV viral RNA was detected in any sample, based on real-time reverse transcriptase PCR. We collected sera from 31 of the 36 sampled individuals, all of which had biomimetic enzyme-linked immunosorbent assay (bELISA) S/N values >0.7 (range: 0.79–1.29) indicating a lack of antibodies to IAVs. Although our sample size is limited, these results indicate no evidence of current or recent previous IAV infection in sampled birds.

Maryland↗
USGS2001

Marine recreation and public health microbiology: Quest for the ideal indicator

Four-fifths of the population of the United States live in close proximity to the oceans or Great Lakes, and approximately 100 million Americans use the marine environment for recreation each year ( Thurman 1994 ). Consequently, contamination of lakes, rivers, and coastal waters raises significant public health issues. Among the leading sources of chemical and biological contamination of these waters and associated beaches are sewer systems, septic tanks, stormwater runoff, industrial wastes, wastewater injection wells, cesspits, animal wastes, commercial and private boat wastes, and human recreation. In 1997, 649 beach closings or advisories were caused by sewage spills and overflows ( NRDC 1998 ). In Florida alone, approximately 500 million gallons of sewage were released along the coast each year during the late 1980s ( Neshyba 1987 ). Thus one of the primary concerns in public health is the risk that humans using the marine environment for recreational activities will encounter microbial pathogens.

BioScience↗
USGS2001

Influences of introduced plague on North American mammals: Implications from ecology of plague in Asia

Intercontinental movements of invasive species continue to modify the world's ecosystems. The plague bacterium ( Yersinia pestis ) has colonized and altered animal communities worldwide but has received much more attention as a human pathogen. We reviewed studies on the ecology of Y. pestis in ancient foci of central Asia and in western North America, where the bacterium apparently has become established much more recently. Although rodent populations on both continents are affected dramatically by epizootics of plague, the epidemiologically important species of Asia demonstrate resistance in portions of their populations, whereas those of North America are highly susceptible. Individual variation in resistance, which is widespread in Asian rodents and allows a microevolutionary response, has been documented in few North American species of rodents. Plague increases costs of sociality and coloniality in susceptible hosts, increases benefits of disease resistance in general, and increases benefits of adaptability to variable environments for species at higher trophic levels. Prairie dogs ( Cynomys ) epitomize taxa with high risk to plague because prairie dogs have uniformly low resistance to plague and are highly social. Relationships to plague are poorly understood for many North American rodents, but more than one-half of the species of conservation concern occur within the geographic range of plague.

Journal of Mammalogy↗
USGS2014

Post-mortem sporulation of Ceratomyxa shasta (Myxozoa) after death in adult Chinook salmon

Ceratomyxa shasta (Myxozoa) is a common gastrointestinal pathogen of salmonid fishes in the Pacific Northwest of the United States. We have been investigating this parasite in adult Chinook salmon ( Oncorhynchus tshawytscha ) in the Willamette River, Oregon. In prior work, we observed differences in the pattern of development of C. shasta in adult salmon compared to juvenile salmon. Adult salmon consistently had large numbers of prespore stages in many of the fish that survived to spawn in the fall. However, myxospores were rarely observed, even though they were exposed and presumably infected for months before spawning. We evaluated the ability of C. shasta to sporulate following fish death because it is reported that myxosores are common in carcasses of Chinook salmon. We collected the intestine from 30 adult salmon immediately after artificial spawning and death (T 0 ). A total of 23 fish were infected with C. shasta based on histology, but only a few myxospores were observed in 1 fish by histology. Intestines of these fish were examined at T 0 and T 7 (latter held at 17 C for 7 days) using quantified wet mount preparations. An increase in myxospore concentrations was seen in 39% of these fish, ranging between a 1.5- to a 14.5-fold increase. The most heavily infected fish exhibited a 4.6-fold increase from 27,841 to 129,352 myxospores/cm. This indicates, supported by various statistical analyses, that under certain conditions presporogonic forms are viable and continue to sporulate after death in adult salmon. Considering the life cycle of C. shasta and anadromous salmon, the parasite may have evolved 2, non-mutually exclusive developmental strategies. In young fish (parr and smolts), the parasite sporulates shortly after infection and is released into freshwater from either live or dead fish before their migration to seawater, where the alternate host is absent. The second strategy occurs in adult salmon, particularly spring Chinook salmon, which become infected upon their return to freshwater in the spring or early summer. For several months throughout the summer, only prespore stages are observed in most fish, even at the time of spawning. But once the fish dies, environmental conditions experienced by C. shasta change and viable presporogonic stages are induced to sporulate. As the post-spawned fish occur in the upper reaches of rivers, the myxospores would be released in a freshwater environment that would provide a reasonable opportunity for them to encounter their freshwater polychaete hosts, which reside downstream.

Journal of Parasitology↗
USGS2021

Loop-mediated isothermal amplification (LAMP) assay for detection of Asian fish tapeworm, Schyzocotyle acheilognathi (Yamaguti, 1934) [syn. Bothriocephalus acheilognathi]

The Asian fish tapeworm ( Schyzocotyle acheilognathi syn. Bothriocephalus acheilognathi ) (AFT) is an invasive parasite that can infect many species of fish, although most hosts are primarily members of Cyprinidae. Pathogenicity has most often been reported in aquaculture settings in fry and fingerling stages of carp ( Cyprinus spp.). More recently, it has been shown to cause growth retardation in the endangered bonytail chub ( Gila elegans ) and found to be widespread in populations of endangered humpback chub ( Gila cypha ) in the Colorado River, Grand Canyon, Arizona. AFT spreads most often through the transport of infected fish, particularly baitfish. Despite its harmful potential, there is no efficient or accurate ante mortem test to detect AFT in water or fish samples before transport. Herein, we report on the development of a sensitive and specific loop-mediated isothermal amplification (LAMP) assay to detect the parasite in under 30 min from laboratory prepared samples. Six LAMP primers were designed to amplify a variable region of the 18S ribosomal RNA gene in AFT with the detection and quantification of DNA on a real-time fluorometer. The limit of detection was 1 × 10 1 copies/µl of DNA extracted from as few as 2 AFT eggs. Future application of our assay would be a low-cost test to rapidly and accurately detect AFT DNA from environmental samples on-site so that preventive actions can be taken to halt the spread of the AFT through the movement of infected fish.

Journal of Parasitology↗
USGS2010

Release of infectious cells from epidermal ulcers in Ichthyophonus sp.–infected Pacific Herring (Clupea pallasii): Evidence for multiple mechanisms of transmission

A common clinical sign of ichthyophoniasis in herring and trout is “sandpaper” skin, a roughening of the epidermis characterized by the appearance of small papules, followed by ulceration and sloughing of the epithelium; early investigators hypothesized that these ulcers might be a means of transmitting the parasite, Ichthyophonus sp ., without the necessity of ingesting an infected host. We examined the cells associated with the epidermal lesions and confirmed that they were viable Ichthyophonus sp. cells that were readily released from the skin into the mucous layer and ultimately into the aquatic environment. The released cells were infectious when injected into the body cavity of specific-pathogen-free herring. Our hypothesis is that different mechanisms of transmission occur in carnivorous and planktivorous hosts: Planktonic feeders become infected by ingestion of ulcer-derived cells, while carnivores become infected by ingestion of whole infected fish.

Journal of Parasitology↗
USGS2007

Evidence of experimental postcyclic transmission of Bothriocephalus acheilognathi in bonytail chub (Gila elegans)

We examined the role that predation of infected conspecific fish and postcyclic transmission might play in the life cycle of the Asian fish tapeworm, Bothriocephalus acheilognathi (Cestoda: Pseudophyllidea) Yamaguti, 1934. Young-of-the-year (YOY) bonytail chub ( Gila elegans ) were exposed to copepods infected with B. acheilognathi and subsequently fed to subadult bonytail chub. Within 1 wk after consumption of the YOY chub, subadults were necropsied and found infected with gravid and nongravid tapeworms. This study provides evidence that postcyclic transfer of B. acheilognathi can occur. Postcyclic transmission may be an important life history trait of B. acheilognathi that merits consideration when studying the impact and distribution of this invasive and potentially pathogenic tapeworm.

New Mexico↗
USGS2006

Update on the distribution of the invasive Asian fish tapeworm, Bothriocephalus acheilognathi, in the U.S. and Canada

The documented range of the invasive and potentially pathogenic Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934 in the United States and Canada is updated based on examination of museum depositions and original field collections. Gravid specimens of B. acheilognathi were collected from the fathead minnow Pimephales promelas Rafinesque in Peter Lake, at the University of Notre Dame Environmental Research Center (UNDERC) Land o' Lakes, Wisconsin. A single immature specimen of the parasite was collected from a white bass, Morone chrysops (Rafinesque) in Lake Winnipeg, Manitoba, Canada. This is the first record of B. acheilognathi in Canada and extends its northern range in the interior of the continent by more than 600 miles over the last documented record. The previous record of B. acheilognathi in Canada, from the northern pikeminnow, Ptychocheilus oregonensis in British Columbia, is a misidentification of Eubothrium tulipai. Examination of selected records of intestinal cestodes from native cyprinids, in the Harold W. Manter Laboratory of Parasitology (HWML, n = 9) collection and in the United States National Parasite Collection (USNPC, n = 8), provided evidence of the parasite in Nebraska and possibly in the upper Colorado River basin. Introductions into Wisconsin-Michigan were due to the stocking of golden shiners, whereas the source of the introduction in Manitoba remains unknown.

Comparative Parasitology↗
USGS2026

Relative activity of three bat species Impacted by white-nose syndrome on the Chesapeake and Ohio Canal National Historical Park

White-nose syndrome, a disease caused by the fungal-pathogen Pseudogymnoascus destructans , has caused drastic reductions in populations of several North American hibernating species of bats including Myotis lucifugus (Little Brown Bat), Myotis septentrionalis (Northern Long-eared Bat), and Perimyotis subflavus (Tricolored Bat). Recent data indicate that populations of Little Brown Bats may be stabilizing and/or increasing in the northeastern region of the US, while others, such as Northern Long-eared Bats, continue to decline. Whether these trends extend to the mid-Atlantic region is currently unknown. To better understand population changes over time, habitat associations, and species dynamics, we developed models of relative activity from bat acoustic data collected on the National Park Service's Chesapeake and Ohio Canal National Historical Park along the Potomac River Corridor in western Maryland between 2016 and 2022. Consistent with pre-disease habitat associations, Little Brown Bats and Tricolored Bats exhibited a positive correlation with proximity to water bodies. Notably, we found Little Brown Bat and Tricolored Bat populations potentially were increasing, whereas Northern Long-eared Bats showed no correlation with examined habitat covariates and had low detection levels, trends consistent with broader declines throughout their range.

Maryland↗
USGS2012

Effects of the amphibian chytrid fungus and four insecticides on Pacific treefrogs ( Pseudacris regilla )

Chemical contamination may influence host-pathogen interactions, which has implications for amphibian population declines. We examined the effects of four insecticides alone or as a mixture on development and metamorphosis of Pacific Treefrogs ( Pseudacris regilla ) in the presence or absence of the amphibian chytrid fungus ( Batrachochytrium dendrobatidis [Bd]). Bd exposure had a negative impact on tadpole activity, survival to metamorphosis, time to metamorphosis, and time of tail absorption (with a marginally negative effect on mass at metamorphosis); however, no individuals tested positive for Bd at metamorphosis. The presence of sublethal concentrations of insecticides alone or in a mixture did not impact Pacific Treefrog activity as tadpoles, survival to metamorphosis, or time and size to metamorphosis. Insecticide exposure did not influence the effect of Bd exposure. Our study did not support our prediction that effects of Bd would be greater in the presence of expected environmental concentrations of insecticide(s), but it did show that Bd had negative effects on responses at metamorphosis that could reduce the quality of juveniles recruited into the population.

Journal of Herpetology↗
USGS2002

Parasite (Ribeiroia ondatrae) infection linked to amphibian malformations in the western United States

Parasites and pathogens can influence the survivorship, behavior, and very structure of their host species. For example, experimental studies have shown that trematode parasites can cause high frequencies of severe limb malformations in amphibians. In a broad-scale field survey covering parts of California, Oregon, Washington, Idaho, and Montana, we examined relationships between the frequency and types of morphological abnormalities in amphibians and the abundance of trematode parasite infection, pH, concentrations of 61 pesticides, and levels of orthophosphate and total nitrate. We recorded severe malformations at frequencies ranging from 1% to 90% in nine amphibian species from 53 aquatic systems. Infection of larvae by the trematode Ribeiroia ondatrae was associated with, and functionally related to, higher frequencies of amphibian limb malformations than found in uninfected populations (≤5%). Parasites were concentrated around the basal tissue of hind limbs in infected anurans, and malformations associated with infection included skin webbings, supernumerary limbs and digits, and missing or malformed hind limbs. In the absence of Ribeiroia, amphibian populations exhibited low (0-5%) frequencies of abnormalities involving missing digits or distal portions of a hind limb. Species were affected differentially by the parasite, and Ambystoma macrodactylum, Hyla regilla, Rand aurora, R. luteiventris, and Taricha torosa typically exhibited the highest frequencies of abnormalities. None of the water-quality variables measured was associated with malformed amphibians, but aquatic snail hosts (Planorbella spp.) were significant predictors of the presence and abundance of Ribeiroia infection. Morphological comparisons of adult specimens of Ribeiroia collected from different sites and raised in experimental definitive hosts suggested that all samples represented the same species - R. ondatrae. These field results, coupled with experimental research on the effects of Ribeiroia on amphibians, demonstrate that Ribeiroia infection is an important and widespread cause of amphibian limb malformations in the western United States. The relevance of trematode infection to declines of amphibian populations and the influence of habitat modification on the pathology and life cycle of Ribeiroia are emphasized as areas requiring further research.

Ecological Monographs↗
USGS2002

Variable breeding phenology affects the exposure of amphibian embryos to ultraviolet radiation

Reduced water depth in dry years has been proposed to interact with ultraviolet- B (UV-B) radiation and a pathogenic fungus to cause episodes of high mortality of amphibian embryos. Observations of breeding phenology of boreal chorus frogs (Pseudacris maculata) in Colorado from 1986 to 2001 show that dry years result in earlier breeding. The earliest and latest dates of maximum calling activity by males were 20 May and 16 June, and the date of maximum calling was strongly related to the amount of snow accumulation during the winter. Surface UV-B flux, estimated from satellite-based measurements, was positively related to date of maximum calling. In dry years, surface UV-B during calling was reduced by an amount similar to that attributed to reduced depth. Although there was a significant trend of increasing UV-B from 1978 to 2001 on the average date (2 June) of maximum calling activity, there was no relationship between year and surface UV-B at actual dates of maximum calling. Exposure to extreme temperatures is an alternative explanation for increased mortality of amphibian embryos in shallow water.

Ecology↗
USGS2008

Spatial elements of mortality risk in old-growth forests

For many species of long-lived organisms, such as trees, survival appears to be the most critical vital rate affecting population persistence. However, methods commonly used to quantify tree death, such as relating tree mortality risk solely to diameter growth, almost certainly do not account for important spatial processes. Our goal in this study was to detect and, if present, to quantify the relevance of such processes. For this purpose, we examined purely spatial aspects of mortality for four species, Abies concolor , Abies magnifica , Calocedrus decurrens , and Pinus lambertiana , in an old-growth conifer forest in the Sierra Nevada of California, USA. The analysis was performed using data from nine fully mapped long-term monitoring plots. In three cases, the results unequivocally supported the inclusion of spatial information in models used to predict mortality. For Abies concolor , our results suggested that growth rate may not always adequately capture increased mortality risk due to competition. We also found evidence of a facilitative effect for this species, with mortality risk decreasing with proximity to conspecific neighbors. For Pinus lambertiana , mortality risk increased with density of conspecific neighbors, in keeping with a mechanism of increased pathogen or insect pressure (i.e., a Janzen-Connell type effect). Finally, we found that models estimating risk of being crushed were strongly improved by the inclusion of a simple index of spatial proximity. Not only did spatial indices improve models, those improvements were relevant for mortality prediction. For P. lambertiana , spatial factors were important for estimation of mortality risk regardless of growth rate. For A. concolor , although most of the population fell within spatial conditions in which mortality risk was well described by growth, trees that died occurred outside those conditions in a disproportionate fashion. Furthermore, as stands of A. concolor become increasingly dense, such spatial factors are likely to become increasingly important. In general, models that fail to account for spatial pattern are at risk of failure as conditions change.

Ecology↗
USGS1998

Effects of ultraviolet radiation on boreal toads in Colorado

Field exposures of Bufo boreas embryos to fractions of ambient UV-B radiation at two sites in Rocky Mountain National Park, Colorado, USA, were conducted to evaluate UV-B as a possible cause of recent severe declines of this species. There were no differences in hatching success of B. boreas embryos exposed to 0–100% of ambient UV-B radiation at either study site, results that are different from those of recent studies in Oregon that found increased mortality of B. boreas embryos exposed to ambient UV-B. The reasons for these differing results are not apparent, and several possible explanations exist, including differences in experimental design, presence or absence of a pathogenic fungus, and geographic genetic variation. Bufo boreas embryos were probably not receiving higher doses of UV-B radiation during the experiments in Oregon compared to the experiments in this study. Results of this study do not support UV-B radiation alone as the cause of the decline of B. boreas during the past 20 yr in the southern Rocky Mountains, but UV-B cannot be dismissed because of the contradictory results from other studies.

Colorado↗